FAQs

Yes. Fire doors can incorporate glazed apertures, also known as vision panels, provided the glazing arrangement is supported by suitable fire-test or assessment evidence.

Vision panels allow people to see through a closed door, helping to prevent collisions and allowing occupants or firefighters to assess potential hazards on the other side. They can also bring natural or borrowed light into corridors and rooms.

The glass, glazing seals, beads, fixings and aperture must all be suitable for the door construction and required fire performance. A correctly specified glazed aperture does not automatically reduce the fire resistance of a door.

A fire door glazing system comprises the components used to create a fire-resisting glazed aperture. These can include fire-resistant glass, intumescent glazing seals or tapes, glazing beads, fixings, liners and other components.

Intumescent glazing seals react to high temperatures during a fire, helping to protect the edges of the glass and surrounding door construction. Depending on the system, they may expand, provide insulation or help hold and protect the glass as temperatures rise.

The glass and seals must be compatible with the complete glazing arrangement. Selecting an intumescent glazing tape solely by its dimensions or claimed fire rating is not sufficient.

The glass must be suitable for the required fire-resistance period and supported for use in the particular doorset and glazing system.

There is no single glass or glazing seal suitable for every FD30 or FD60 fire door. The specification depends on the door construction, aperture dimensions, glazing beads, fixings, seals and supporting evidence.

Different types of fire-resistant glass provide different levels of protection. Changing the manufacturer, construction or thickness of the glass may affect its performance, even where the alternative carries a similar fire-resistance classification.

These classifications describe different aspects of fire performance:

• E – Integrity: The ability to resist the passage of flames and hot gases for a specified period.
• EW – Integrity and radiation control: Integrity combined with a limit on heat radiation.
• EI – Integrity and insulation: Integrity combined with limiting the temperature rise on the unexposed side.

The required classification depends on the application and fire strategy. A stated fire-resistance period alone does not necessarily provide enough information to specify the glass.

The complete glazing system must be capable of achieving the performance required from the fire-resisting element.

Glazing beads, liners and fixings form part of the fire-resisting glazing system and must be suitable for the tested or assessed configuration.

The material, dimensions, profile, density and fixing method of the glazing beads can all affect performance. Some systems also require glazing liners around the aperture to provide additional protection to the exposed door core and surrounding construction.

Not every glazing system requires the same components. The correct arrangement must follow the doorset and glazing-system evidence rather than selecting individual products based on appearance or a general fire-rating claim.

There is no universal maximum size or position for a vision panel in a fire door. The permitted dimensions depend on the door construction, fire-resistance period, glass, glazing system and supporting evidence.

The number, size, shape, spacing and position of glazed apertures may all be restricted. Distances from door edges, other apertures and ironmongery can also be important.

Larger apertures remove more material from the door leaf and expose a greater area of glazing during a fire. Multiple apertures or unusual shapes must therefore be supported by suitable evidence.

An aperture should not be enlarged beyond its permitted dimensions simply because the same glass and glazing seals are being used.

Potentially, but only where the door construction, certification and supporting evidence permit the modification.

Cutting an aperture changes the construction of the door leaf. Installing fire-resistant glass afterwards does not automatically preserve the door's original fire rating.

Some third-party certification schemes, including BWF-CERTIFIRE, do not permit glazing apertures to be cut on site. Always check the relevant scheme requirements and doorset documentation before making alterations.

Where modifications are permitted, the work should be undertaken by an appropriately competent organisation using a glazing arrangement supported for that particular door.

Yes, provided the replacement glass and glazing system are supported by appropriate evidence for the existing doorset.

Wired glass and clear fire-resistant glass are not automatically interchangeable. Different products may have different constructions, thicknesses, edge clearances and glazing requirements, even where they have the same nominal fire-resistance period.

The replacement must be compatible with the door, glazing seals, beads and fixings. Simply choosing glass that fits the opening or carries a similar fire rating is not sufficient.

Only where the replacement or existing components are suitable for the glazing system and supported by the relevant fire-test or assessment evidence.

Two intumescent glazing seals may look identical but behave differently when exposed to fire. Substituting one product for another, or using it with a different glass type, requires suitable supporting evidence.

Glazing seals that have been damaged, distorted or disturbed during glass removal should not automatically be reused. The same applies to glazing beads and fixings that are damaged or can no longer be fitted correctly.

Check the glazing-system documentation and manufacturer's instructions to establish which components can be reused and which must be replaced.

Check the glass for cracks and damage, and inspect the glazing seals, beads and fixings for deterioration, looseness or missing sections. All components should be secure and in good condition, with no obvious unauthorised alterations to the aperture.

Any damage should be investigated against the doorset documentation and glazing-system evidence. Repairs must use suitable components and installation methods rather than relying on appearance or dimensions alone.

Fire resistance and impact safety are separate requirements. Depending on the location and dimensions of the glazing, impact safety requirements may also apply. In England, these are addressed by Approved Document K. The selected glass must meet all applicable requirements, not just those relating to fire resistance.

An acoustic sliding door seal reduces sound passing through the gaps around a sliding door. Specialist seals close the gaps at the head, threshold and vertical edges when the door is shut, while allowing it to slide freely when opened.

Sliding doors are more challenging to seal than hinged doors because they move parallel to the opening and need clearance around the leaf. Acoustic sealing systems are designed to close these gaps when the door reaches its closed position without interfering with its movement.

Sliding doors can achieve good levels of sound reduction with the right combination of door construction and acoustic seals, although soundproof is rarely an accurate description.

Sound can travel through gaps beneath the door, around the vertical edges and above the leaf. Even small openings can significantly reduce acoustic performance, so sealing the bottom gap alone may not be enough.

The final result depends on the door leaf, seals, surrounding construction and installation. Individual seal test results should not be treated as guaranteed acoustic performance for every door assembly.Sliding doors can achieve good levels of sound reduction with the right combination of door construction and acoustic seals, although soundproof is rarely an accurate description.

Sound can travel through gaps beneath the door, around the vertical edges and above the leaf. Even small openings can significantly reduce acoustic performance, so sealing the bottom gap alone may not be enough.

The final result depends on the door leaf, seals, surrounding construction and installation. Individual seal test results should not be treated as guaranteed acoustic performance for every door assembly.Sliding doors can achieve good levels of sound reduction with the right combination of door construction and acoustic seals, although soundproof is rarely an accurate description.

Sound can travel through gaps beneath the door, around the vertical edges and above the leaf. Even small openings can significantly reduce acoustic performance, so sealing the bottom gap alone may not be enough.

The final result depends on the door leaf, seals, surrounding construction and installation. Individual seal test results should not be treated as guaranteed acoustic performance for every door assembly.Sliding doors can achieve good levels of sound reduction with the right combination of door construction and acoustic seals, although soundproof is rarely an accurate description.

Sound can travel through gaps beneath the door, around the vertical edges and above the leaf. Even small openings can significantly reduce acoustic performance, so sealing the bottom gap alone may not be enough.

The final result depends on the door leaf, seals, surrounding construction and installation. Individual seal test results should not be treated as guaranteed acoustic performance for every door assembly.Sliding doors can achieve good levels of sound reduction with the right combination of door construction and acoustic seals, although soundproof is rarely an accurate description.

Sound can travel through gaps beneath the door, around the vertical edges and above the leaf. Even small openings can significantly reduce acoustic performance, so sealing the bottom gap alone may not be enough.

The final result depends on the door leaf, seals, surrounding construction and installation. Individual seal test results should not be treated as guaranteed acoustic performance for every door assembly.Sliding doors can achieve good levels of sound reduction with the right combination of door construction and acoustic seals, although soundproof is rarely an accurate description.

Sound can travel through gaps beneath the door, around the vertical edges and above the leaf. Even small openings can significantly reduce acoustic performance, so sealing the bottom gap alone may not be enough.

The final result depends on the door leaf, seals, surrounding construction and installation. Individual seal test results should not be treated as guaranteed acoustic performance for every door assembly.Sliding doors can achieve good levels of sound reduction with the right combination of door construction and acoustic seals, although soundproof is rarely an accurate description.

Sound can travel through gaps beneath the door, around the vertical edges and above the leaf. Even small openings can significantly reduce acoustic performance, so sealing the bottom gap alone may not be enough.

The final result depends on the door leaf, seals, surrounding construction and installation. Individual seal test results should not be treated as guaranteed acoustic performance for every door assembly.Sliding doors can achieve good levels of sound reduction with the right combination of door construction and acoustic seals, although soundproof is rarely an accurate description.

Sound can travel through gaps beneath the door, around the vertical edges and above the leaf. Even small openings can significantly reduce acoustic performance, so sealing the bottom gap alone may not be enough.

The final result depends on the door leaf, seals, surrounding construction and installation. Individual seal test results should not be treated as guaranteed acoustic performance for every door assembly.Sliding doors can achieve good levels of sound reduction with the right combination of door construction and acoustic seals, although soundproof is rarely an accurate description.

Sound can travel through gaps beneath the door, around the vertical edges and above the leaf. Even small openings can significantly reduce acoustic performance, so sealing the bottom gap alone may not be enough.

The final result depends on the door leaf, seals, surrounding construction and installation. Individual seal test results should not be treated as guaranteed acoustic performance for every door assembly.

A sliding door may need a combination of automatic seals at the head and threshold, together with vertical perimeter seals.

The correct arrangement depends on the door construction, sliding mechanism, gap dimensions, acoustic requirements and whether the door is latched or unlatched. Double sliding doors also need suitable sealing at the meeting stiles between the two leaves.

Norseal offers complete sliding door sealing solutions for different configurations, including latched, unlatched and pocket doors. Specifying a coordinated system can be preferable to selecting individual seals separately.

An automatic sliding door drop seal closes the gap beneath the door when the leaf reaches its closed position. The sealing element lowers into contact with the floor or threshold and retracts when the door opens.

This allows the door to slide without the seal continually dragging across the floor, helping to minimise friction, wear and opening resistance.

Sliding door drop seals use activation mechanisms suited to sideways movement. A drop seal designed for a conventional hinged door should not automatically be assumed suitable for a sliding door.

Yes. Specialist acoustic sealing systems are available for pocket doors, where the door leaf slides into a cavity within the wall.

The sealing arrangement must allow the door to move into the pocket while closing the relevant gaps when it reaches its closed position. This may involve automatic top and bottom seals together with vertical seals at the closing and pocket edges.

Ideally, acoustic sealing should be considered when specifying the pocket-door system rather than added as an afterthought.

Yes, in some cases. Surface-mounted acoustic seals can offer a retrofit solution without replacing the complete sliding door. Concealed seals, which are incorporated into the door construction, provide a more discreet appearance and are often better suited to new installations.

Before selecting a retrofit system, check the existing door construction, sliding mechanism, available fixing space and gap dimensions.

A single additional seal may provide limited improvement if significant gaps remain elsewhere around the opening.

The maximum gap depends on the individual seal and its operating range. Measure the gaps around the door before selecting a product, as a larger operating range is not a substitute for correct door preparation and installation.

Some automatic seals can accommodate a degree of variation across the threshold. However, significantly uneven floors may prevent continuous contact and require a suitable threshold or remedial work.

Some sliding door seals can also be cut to length, within the manufacturer's limits. Automatic seals contain internal mechanisms, so always check the permitted cutting dimensions before shortening them.

Yes. Automatic drop seals can retract when the door opens, leaving the floor clear without a permanent raised threshold. This can be particularly useful for wheelchair users, wheeled equipment and other applications requiring barrier-free access.

Correctly specified automatic seals are also designed to minimise additional opening resistance.

The complete door assembly must still meet the project's accessibility requirements, including any applicable opening-force, clearance and operating requirements.

A bottom seal only addresses the gap beneath the door. Sound may still be passing through gaps at the head, vertical edges or meeting stiles, or through the surrounding wall and frame construction.

Specialist perimeter seals can help close the vertical gaps when the door is shut. The correct arrangement depends on whether the door is latched or unlatched, how it closes against the frame and whether it slides across the wall or into a pocket.

Improving acoustic performance means identifying all the sound paths rather than concentrating on a single gap.

When the door is closed, the seals should make continuous contact with their intended sealing surfaces without preventing the door from closing properly.

Automatic seals should engage consistently when the door closes and retract when it opens. They should not continually drag along the floor during normal operation.

Check the seals periodically for wear, damage, loose fixings and changes in adjustment. Visible gaps, excessive friction or incomplete contact may indicate that adjustment or maintenance is needed.

An intumescent seal is a heat-reactive fire protection product used around fire-resisting doorsets. When exposed to high temperatures during a fire, the material expands, helping to close the gaps around the door leaf and restrict the passage of flames and hot gases.

Fire doors need operating gaps to open and close properly, but these gaps can become routes for fire to spread. Intumescent seals are commonly fitted into grooves in the door edge or frame, although the exact arrangement depends on the tested or assessed doorset. 

Activation temperature and expansion characteristics vary according to the intumescent material and product formulation.

Common materials include graphite and hydrated sodium silicate, which react differently when exposed to heat. Different materials can produce different expansion pressures and directions, affecting how they perform within a doorset.

These materials are not automatically interchangeable. The correct type should be selected using the test or assessment evidence supporting the particular fire door, rather than activation temperature alone.

Intumescent strips expand when exposed to the heat of a fire, helping to restrict the passage of flames and hot gases through the gaps around a door.

Smoke seals perform a different function. They restrict smoke passing through gaps around a closed door before temperatures are high enough to activate the intumescent material.

Where both fire resistance and smoke control are required, a combined intumescent and smoke seal may be specified. These commonly incorporate intumescent material with a brush or blade smoke-sealing element.

Whether smoke sealing is required depends on the door's location, designation, specification and supporting evidence.

There is no universal intumescent seal size for every FD30 or FD60 fire door. Although different fire-resistance periods may require different sealing arrangements, the fire rating alone does not determine the correct product.

Seal width, thickness, quantity, material and position depend on the door construction, leaf dimensions, configuration and supporting test or assessment evidence.

Two doorsets with the same fire rating may require different intumescent seals. Always check the manufacturer's specification rather than relying on a general rule about seal dimensions.

Intumescent strips are commonly fitted around the vertical edges and head of a fire door, either in grooves in the door leaf or in the frame.

Some doorsets use seals in more than one location, while double fire doors may also require protection at the meeting stiles between the leaves. Rebated and square meeting stiles can require different arrangements.

Intumescent seals are not necessarily required along the bottom edge, although some tested configurations may specify additional protection there.

The position, number and dimensions of the seals must follow the doorset manufacturer's instructions and supporting fire evidence.

The permitted gaps between a fire door and its frame depend on the doorset's tested or assessed configuration and manufacturer's instructions.

Operating gaps are necessary for the door to function, but excessive gaps can affect fire resistance and smoke control. Intumescent seals are designed to work within specified tolerances and should not be used to compensate for gaps outside those limits.

Where gaps are too large, the door or frame may require remedial work rather than simply fitting a larger seal.

Only where the alternative is supported by suitable test or assessment evidence for the doorset.

Two seals may have identical dimensions but contain different intumescent materials or have different expansion characteristics. Substituting graphite for sodium silicate, changing the seal thickness or altering its position can affect fire performance.

The replacement must be suitable for the particular door construction and configuration. Where there is any doubt, check the original doorset documentation or seek technical advice before making a substitution.

Intumescent strips are commonly installed in accurately sized grooves in the door leaf or frame. They may be secured using adhesive backing or another fixing method specified by the manufacturer.

Groove dimensions, seal position and fixing arrangements must follow the doorset's installation requirements and supporting evidence.

Intumescent seals can sometimes be retrofitted, but the existing door construction, condition and fire-performance evidence must first be assessed. Simply adding intumescent strips does not turn an ordinary door into a compliant fire-resisting doorset.

Some doorsets also require intumescent protection around hinges, locks and other ironmongery. See our Hardware Protection FAQs for further guidance.

Intumescent and smoke seals should be checked during routine fire door inspections. Missing, loose, damaged, heavily contaminated or deteriorated seals should be investigated and replaced where necessary using products supported by the doorset specification.

Painting depends on the seal and manufacturer's instructions. Some products may tolerate limited decoration, but excessive paint, contamination or coating of smoke-sealing elements can affect their operation.

Never assume that all intumescent strips can be painted or that a replacement with the same dimensions will be suitable.

Intumescent seals are generally assessed as part of a fire-resisting doorset rather than as independent products.

In the UK, fire-resistance evidence for doorsets may be based on testing to BS 476-22 or EN 1634-1, depending on the product and specification.

The withdrawal of BS 476-22 references from Approved Document B will change the accepted route for demonstrating fire resistance for new products and specifications. During the transition, it is particularly important to establish which test evidence supports the doorset.

The evidence should confirm the required seal material, dimensions, quantity and position, along with relevant door construction details and any associated ironmongery protection. The aim is to reproduce a configuration supported by appropriate fire-test or assessment evidence.

Intumescent ironmongery protection includes pads, wraps, kits and sheets fitted around or behind hinges, locks, closers and other hardware on fire doors.

Installing ironmongery can involve removing fire-resisting material from the door leaf or frame. Metal components can also conduct heat into the surrounding construction. 

Intumescent protection reacts to high temperatures, helping to protect these vulnerable areas and reduce heat transfer during a fire.

Whether protection is needed depends on the hardware, door construction, fire-resistance period and supporting test or assessment evidence.

No. Some hardware and doorset configurations have demonstrated the required fire performance without additional intumescent protection, while others have been tested with pads, wraps or kits.

A fire-rated hinge, lock or closer may still require protection if it formed part of the tested arrangement. Omitting it could mean the installation no longer matches the configuration for which fire performance was demonstrated.

Always check the fire-test or assessment evidence for both the hardware and doorset rather than assuming that a fire rating means additional protection is unnecessary.

Sometimes. Where required, intumescent hinge pads are normally fitted behind the hinge blades, between the hinge and the timber of the door leaf or frame.

Some tested configurations require pads behind both hinge blades, while others have different requirements. The specified material, thickness, dimensions and coverage must be followed.

Pads should sit properly behind the hardware without interfering with hinge operation or fixings. A fire-tested hinge should not automatically be assumed suitable for installation without intumescent protection.

There is no universal hinge pad thickness for every FD30 or FD60 fire door. Different tested configurations use different intumescent materials, dimensions, thicknesses and arrangements.

A thicker pad is not necessarily better. Different intumescent materials have different expansion and pressure characteristics, and increasing the thickness can affect how the hardware fits and performs.

The correct specification must come from the hinge and doorset's supporting fire evidence. Pre-cut pads are available for common hinge sizes, and Norseal can supply cut-to-size protection where standard dimensions are unsuitable.

Mortice locks often require intumescent protection because installing the lock involves removing a substantial section of the door core. The metal lock body can also transfer heat into the surrounding construction.

An intumescent lock kit contains pre-cut components designed to protect specific parts of the installation. Depending on the lock and supporting evidence, this may include protection around the lock body and behind the forend, strike plate or keep.

Not every lock requires the same arrangement. The material, thickness and extent of protection must match the tested or assessed configuration.

They may do. Concealed door closers and recessed flush bolts can involve removing significant amounts of material from the door leaf or frame, potentially affecting fire performance.

Other hardware, including latches and recessed ironmongery, may also require protection.

Where intumescent protection forms part of the tested or assessed installation, the specified material and arrangement must be used. There is no universal list of hardware that always requires protection, so the requirements should be checked for each doorset and hardware combination.

Graphite and INTERDENS® are different intumescent materials that react differently when exposed to heat.

Both can be used for ironmongery protection in appropriate applications, but they are not automatically interchangeable. Their expansion and pressure characteristics can differ, affecting how they protect the surrounding door construction.

The correct material must be determined by the evidence supporting the hardware and doorset. Pads with identical dimensions may not provide equivalent performance, so substitutions should never be made without suitable supporting evidence.

Yes, provided the material and supporting fire evidence permit it. Intumescent sheet can be used to produce pads or protection for hardware that does not suit standard pre-cut products.

The finished protection must provide the specified material, thickness, dimensions and coverage. Accurate cutting is important, particularly where consistent protection is required across multiple doorsets.

Norseal supplies intumescent sheet and offers a cut-to-size service for hinges, locks, closers and other ironmongery. This can be useful for door manufacturers and ironmongery specialists working with recurring hardware configurations.

Only where the replacement or existing protection is suitable for the new hardware and supported by the relevant fire-test or assessment evidence.

A replacement hinge, lock or other component may have different requirements for intumescent material, thickness, dimensions or positioning. Similarly, pads that look identical may use different materials and behave differently in a fire.

Whenever fire door hardware is changed, review the associated intumescent protection. Identify the original specification where possible and confirm that any replacement or reused material remains appropriate.

Check for missing, damaged, displaced or incorrectly fitted protection wherever it is visible or accessible. Also look for signs that hinges, locks or other hardware have been changed without reviewing the associated intumescent protection.

If a doorset was tested or assessed with protection around particular hardware, omitting it means the installed configuration no longer matches the supporting evidence. Any missing protection should be investigated and rectified using the correct material and installation details.

The doorset and hardware documentation should establish the required protection, including material, thickness, position and coverage. Fire-resistance evidence may include testing to BS 476-22 or EN 1634-1, but compliance with a test standard alone does not establish that a particular combination of hardware and intumescent protection is suitable.

Specialist glass door seals are designed to close gaps around the edges of glass doors and beneath the door leaf. They can help reduce sound transmission while allowing the door to operate normally.

Different systems are available for hinged, pivot, sliding and frameless glass doors. These include perimeter seals, automatic drop seals and integrated or surface-mounted solutions. The right choice depends on the door configuration, glass specification, gap dimensions and required acoustic performance.

Even relatively small gaps around a glass door can allow sound to pass through. Although the glass itself may provide good acoustic performance, unsealed gaps around the edges can significantly reduce the performance of the complete assembly.

Common sound leakage points include the threshold, vertical edges and head of the opening. Acoustic seals help close these gaps, reducing airborne sound transmission. Frameless doors can be particularly challenging because they lack the conventional rebates and frames used to accommodate perimeter seals.

An automatic drop seal is fitted along the bottom edge of a glass door to close the gap between the door and the floor or threshold.

When the door closes, a mechanism activates the seal, lowering it into contact with the floor. As the door opens, the seal retracts automatically, allowing the door to move freely without the sealing element continually dragging across the floor.

Automatic drop seals can provide effective threshold sealing without restricting normal door operation, provided they are correctly specified, adjusted and installed.

Yes. Specialist acoustic seals are available for frameless glass doors, including systems that can be fixed directly to the glass without conventional timber frames or rebates.

Integrated systems form part of the original door design and can provide a discreet finish. Surface-mounted systems are fixed to the glass or door assembly and can be particularly useful for existing doors.

The sealing arrangement must suit the glass construction, door configuration and required acoustic performance.

Glass door seals and their carriers are designed to accommodate specific glass thicknesses and constructions.

Specialist systems are available for common toughened glass thicknesses, including 8mm and 10mm, as well as a range of laminated glass thicknesses. However, a seal suitable for toughened glass should not automatically be assumed suitable for laminated glass.

Before choosing a seal, establish the exact glass thickness and construction, door configuration, gap dimensions, fixing method and required acoustic performance. Norseal can advise on suitable options for toughened and laminated glass doors.

Yes, although the seal must be suitable for the particular door arrangement.

Automatic drop seals are available specifically for hinged glass doors. Specialist systems can also be used on sliding doors, where the seal must accommodate sideways movement without restricting operation.

Pivot doors may also be suitable, depending on the pivot position, movement of the leaf, glass thickness, threshold clearance and activation method.

A drop seal designed for a conventional hinged door should not automatically be assumed suitable for a sliding or pivot door.

Generally, yes. Hinged doors can close against perimeter seals, creating compression that helps form an effective seal. Sliding doors need sufficient clearance for the leaf to move sideways, making continuous acoustic sealing more challenging.

Specialist seals can be used at the vertical edges, head and threshold to close gaps when the sliding door reaches its fully closed position.

Good acoustic performance depends on the glass, sliding mechanism, perimeter seals, threshold seal and interfaces with the surrounding construction. Sealing the bottom gap alone may not provide the required performance.

Yes. Some glass door sealing systems are designed for surface-mounted, bonded or adhesive installation, allowing them to be fitted without drilling or replacing the glass.

The fixing method must be compatible with the glass and seal. Before installation, check the glass thickness, available mounting space, door movement and threshold gap.

Always follow the manufacturer's instructions for surface preparation, fixing and any bonding or curing requirements. Installation methods suitable for timber doors should not automatically be used on toughened or laminated glass.

The permitted clearance depends on the individual drop seal. Each product has a defined operating range, so the gap beneath the door must be measured before selecting a seal.

Some automatic drop seals can accommodate a degree of variation across the threshold as the sealing mechanism lowers. However, significant floor irregularities may require a suitable threshold or another solution to provide a consistent sealing surface.

Some glass door drop seals can also be shortened to suit the required dimensions, but the permitted amount and cutting method vary by product. Always check the manufacturer's instructions, particularly where the seal contains an automatic mechanism.

A correctly installed glass door seal should close the intended gap continuously when the door is shut and release or retract when it opens. An automatic drop seal should contact the floor or threshold without preventing normal door operation.

Visible gaps, uneven contact or excessive dragging may indicate that adjustment is needed.

If sound is still leaking after fitting a drop seal, the problem may be elsewhere. A bottom seal only addresses the threshold gap; sound can still travel through gaps around the head and vertical edges, interfaces with the frame or other weak points in the surrounding partition.

The acoustic performance of an individual seal should not be taken as a guaranteed rating for the complete door assembly. Overall performance depends on the tested configuration and how effectively all sound paths are controlled.

A fire door will normally require intumescent seals to restrict the spread of fire through the gaps around the door leaf. Where smoke control is required, smoke seals will also be needed. These functions can sometimes be combined within a single product.

Other seals may be required for acoustic performance or to control smoke leakage at the threshold. The correct combination depends on the tested or assessed doorset, its fire resistance and smoke-control requirements, and any additional performance requirements.

For more information about intumescent materials, how they work and how they're specified, see our Intumescent Seals FAQs.

Intumescent seals expand when exposed to the heat of a fire, helping to close the gaps around the door and restrict the passage of flames and hot gases.

Smoke seals work differently. They restrict cold smoke passing through the gaps before temperatures are high enough to activate the intumescent material. Combined fire and smoke seals incorporate both intumescent material and a smoke-sealing element, such as a brush or fin.

Not every fire door requires smoke seals. Their use depends on the doorset's location, specification and smoke-control requirements. Where smoke control is required, the appropriate seals must be included.

Yes. Multifunctional door seals are available that can contribute to fire resistance, smoke control and acoustic performance.

However, an intumescent or smoke seal does not automatically provide a particular acoustic rating. Acoustic performance depends on the complete door assembly and its tested configuration, and there must be suitable evidence for each performance requirement.

tart with the doorset manufacturer's specification and supporting test or assessment evidence. This should identify the required seal type, material, dimensions and position.

The fire rating alone is not enough to determine the correct seal. Two FD30 doors, for example, may have different constructions and sealing arrangements. Similarly, an FD60 door does not automatically require a larger seal than an FD30 door.

The choice between brush and fin smoke seals also depends on the doorset, operating gaps and required performance. Whichever is specified must make effective contact when the door is closed without preventing it from operating correctly.

Not necessarily. Two seals with identical dimensions may have different intumescent materials, activation temperatures, expansion characteristics and pressure-generating properties.

The replacement must match the doorset specification or be supported by suitable test or assessment evidence as an appropriate alternative. This applies to the seal's material, dimensions, location and performance.

If you're unsure which seal was originally specified, check the doorset documentation, certification, manufacturer's information and any product markings. Appearance and dimensions alone may not be enough to identify it.

Double fire doors can require different sealing arrangements because of the additional gap where the two door leaves meet.

The meeting stiles, head and jambs must be sealed in accordance with the tested or assessed doorset configuration. Rebated and square meeting stiles may require different arrangements, including appropriate intumescent and smoke seals where specified.

The seals must also allow both leaves to operate correctly and close fully.

Fire door seals should be checked during routine fire door inspections and maintenance. The appropriate frequency depends on the building, door location, usage and applicable fire-safety requirements. High-use or higher-risk doors may need more frequent attention.

Check that seals are present, securely fitted and in good condition. Look for missing sections, loose or damaged seals, excessive paint and smoke-sealing elements that are torn, flattened or no longer making proper contact. The condition and operation of the complete fire door should also be considered.

A fire door seal should be replaced if it is missing, damaged, deteriorated or can no longer perform its intended function. Damaged intumescent or smoke-sealing material will often need replacing, although some minor issues may be repairable.

A missing or damaged smoke seal can allow cold smoke to pass around the door where smoke control is required. Replacement may also be necessary following alterations to the door or its hardware.

Age alone does not mean a seal needs replacing. Its condition and ability to perform as specified are more important than an arbitrary replacement interval.

Always use the doorset specification or supporting evidence to identify the correct replacement, rather than assuming any similarly sized fire-rated seal will be suitable.

Painting over intumescent seals depends on the product and manufacturer's guidance. Excessive paint or coatings can affect components and make inspection difficult, so the requirements should be checked before painting. If seals have already been painted, establish their identity and condition before deciding whether they need attention.

Smoke seals can potentially be added to an existing fire door, but doing so changes the doorset configuration. First establish whether smoke control is required and check the original specification.

Any additional seal must be suitable for the doorset and must not prevent the door from closing fully and reliably.

No. A fire door is a complete assembly whose fire resistance is supported by appropriate test or assessment evidence.

Adding intumescent strips to an ordinary door does not demonstrate that it will achieve a particular period of fire resistance. The door leaf, frame, hardware, seals and other components must form a suitable, evidenced doorset assembly.

A door finger guard is a safety device designed to prevent fingers becoming trapped between a door leaf and frame as the door closes. The risk is greatest around the hinged edge, where the gap can create considerable crushing force, particularly on heavy doors, self-closing doors or doors affected by wind and pressure differences.

Finger protection can take several forms, including gap covers, hinge-knuckle protectors and complete systems protecting both sides of the hinged edge.

Not necessarily, but both sides should be considered. Hinge-side finger guards cover the larger gap that opens between the door leaf and frame, while knuckle-side protectors cover the smaller trapping point around the hinge on the opposite side.

A gap cover may be sufficient where only the main hinge-side opening presents a risk. Where both sides present a hazard, a complete finger-protection system may be more appropriate.

Start by assessing the trapping points, the door's construction and how it operates. Consider the hinge arrangement, opening angle, door dimensions, required protection height and whether one or both sides need protection.

The people using the building are equally important. There is no single guard height suitable for every application, and greater coverage may be appropriate where children or vulnerable people are at risk. Finger guards must accommodate the door's maximum opening angle without restricting normal use, accessibility or escape.

There is no blanket UK requirement for every door in a school, nursery or other building to have a finger guard. However, building owners, employers and organisations have responsibilities to identify and manage foreseeable risks.

Schools and nurseries should pay particular attention to doors used by younger children, especially near play areas, corridors and places where children gather or queue. Heavy doors, self-closing doors and doors that may close suddenly also warrant consideration.

The need for finger protection should be determined by a risk assessment of each door, rather than assuming every door requires the same solution.

Finger guards are commonly used in healthcare facilities, care environments, public buildings and other locations where people may be particularly vulnerable to finger-trapping injuries.

Young children and people with some physical, cognitive or sensory impairments may be at increased risk. Doors near waiting areas and other busy locations can also present hazards.

In hospitals and care environments, specification should consider hygiene, durability, cleaning requirements, door operation and any fire safety or accessibility requirements.

Yes, provided the finger-protection system is suitable for the fire door and does not interfere with its performance.

The door must still close fully into its frame, and the guard must not obstruct its movement, seals, hinges or other components. The door set's supporting evidence and the manufacturer's requirements should be checked before fitting finger protection to a fire-resisting door.

Yes. Many surface-mounted finger guards are designed for retrofit installation and can be fitted to existing timber or metal doors.

The product and fixing method must be suitable for the door and frame construction, hinge arrangement and opening angle. Many surface-mounted systems can be installed without removing the complete door, although this depends on the product and fixing arrangement.

Integrated finger-protection systems are another option, incorporating protection into the door assembly itself. These can provide a less conspicuous solution when finger safety is considered during the initial door design.

nstallation depends on the type of finger guard and the door construction. Surface-mounted systems are generally fixed between the door leaf and frame, allowing the protective material to move with the door while continuing to cover the trapping point.

Correct positioning is essential. The guard must remain effective throughout the door's intended opening range without becoming stretched, folded or trapped, or interfering with hinges, door closers or other hardware.

Installation should follow the manufacturer's instructions, and the finished door should open and close correctly.

Finger guards should be included in routine door inspections because they are repeatedly moved or flexed during use. Inspection frequency depends on the environment and how heavily the door is used.

Busy schools, nurseries, healthcare facilities and other high-traffic buildings may need more frequent checks. Inspect the guard for loose fixings, tears, cracks, stretching or other deterioration, and check that it continues to cover the trapping point throughout the door's movement.

A finger guard should be repaired or replaced if damage, wear or deterioration prevents it from providing effective protection.

Loose fixings, splits, tears, excessive stretching or deformation should be investigated promptly. Simply refixing a damaged guard may not be sufficient if the material itself has deteriorated.

Replacement may also be necessary if the door, hinges or opening arrangement have changed. Where a damaged guard creates a significant risk, temporary safety measures may be needed until the problem is resolved.

An air transfer grille is a ventilation component that allows air to pass from one space to another through a door, wall or other building element.

They are used where airflow is required between adjoining spaces without leaving a door open or providing a separate ventilation route.

An air transfer grille provides a permanent path for air to move between spaces. It can form part of a building's ventilation strategy, helping air circulate between rooms or areas while doors remain closed.

The amount of air that can pass through depends on factors such as the grille's dimensions, design, and available free area.

Air transfer grilles can be used where ventilation or air movement is required between adjoining spaces, but a door or wall needs to remain in place.

Applications vary considerably, so the grille should be selected according to the ventilation requirement and any other performance requirements of the door, wall or partition.

An intumescent air transfer grille is designed to allow normal airflow while also forming part of a fire-resisting installation.

Under everyday conditions, air can pass through the grille. When exposed to the high temperatures associated with fire, the intumescent material expands to close the openings and help restrict the passage of fire and hot gases.

Intumescent air transfer grilles contain heat-reactive material within their construction. In a fire, this material expands substantially, progressively closing the grille's open area.

Once activated, the expanded intumescent material forms a barrier that helps maintain the installation's required fire resistance. The precise performance depends on the grille and the tested configuration in which
it is used.

Air transfer grilles are used in a wide range of commercial, public and residential buildings wherever controlled airflow is required between spaces.

Typical applications can include doors, walls and ventilation systems. Where the surrounding element is required to provide
fire resistance, an appropriately tested intumescent air transfer grille may be
required.

A standard air transfer grille provides ventilation but is not necessarily designed to protect the opening in a fire-resisting door.

A fire-rated air transfer grille incorporates intumescent material that expands when heated, closing the ventilation openings during a fire. Its suitability depends on the fire-test evidence for the particular
installation.

Free area is the proportion of the grille through which air can actually pass. It is usually expressed as a percentage of the grille's overall face area.

 This matters because two grilles with the same external dimensions may provide different amounts of available airflow. Norseal's PYROGRILLE 100, for example, provides approximately 60% free area.

Start with the ventilation requirement, then consider the performance requirements of the door, wall, or duct in which the grille will be installed.

Important factors can include the required free area, grille dimensions, fire-resistance period, substrate, location, and whether additional requirements, such as smoke or acoustic control, apply. Where fire resistance is required, the proposed installation should be supported by appropriate test or assessment evidence.

The required size depends partly on the airflow or free area needed for the ventilation design.

Where the grille is being fitted into a fire-resisting door or wall, however, you must also check the sizes and configurations covered by the grille's fire-test evidence and the evidence for the element into which it is being installed. A larger opening cannot simply be assumed to be acceptable.

Potentially, but only if the product is supported for both applications.

Doors and walls are different constructions and may require different installation details. The fact that an intumescent grille has demonstrated fire performance in one type of construction does not
automatically demonstrate the same performance in another.

The grille should be appropriate for the required fire resistance of the element in which it is installed.

 For example, an aperture in a 60-minute fire-resisting door set requires a grille and installation arrangement to achieve the required performance. The rating of the grille should not be considered separately from the door or wall in which it is fitted.

Yes, intumescent air transfer grilles are available with test evidence for different fire-resistance periods.

Norseal's PYROGRILLE 100 has been tested in fully operational FD30 and FD60 timber door sets. Always check that the relevant evidence covers the particular grille size, door or wall construction and
installation arrangement.

An intumescent air transfer grille and its decorative or protective cover grille perform different functions. The intumescent element provides the fire-protection function, while a cover grille can provide protection and a more suitable finished appearance.

Whether a cover is required, and what type can be used, should follow the manufacturer's installation details and the tested configuration.

It can if an unsuitable component or arrangement is used. Cover grilles should therefore be selected and installed in accordance with the evidence and instructions for the intumescent ATG. Avoid assuming that any grille of the correct dimensions can simply be fitted over a fire-rated product.

 

Yes, but the grille and aperture must be compatible with the fire door set and supported by appropriate evidence.

Cutting an opening into a fire door changes its construction, so it should never be assumed that any fire-rated grille can simply be added to any fire door. The door set evidence, permitted aperture
dimensions and grille installation details all need to be checked.

Yes, provided the grille and installation are supported for use in the particular FD30 door set.

Check the door construction, permitted aperture size, position, grille dimensions and installation requirements against the relevant test or assessment evidence.

Yes, where appropriate evidence supports the grille and installation in the FD60 door set concerned.

Do not assume that a grille suitable for an FD30 door is automatically suitable for an FD60 door. The required performance and
tested configuration should be checked before specification or installation

Potentially, but this should never be treated as a simple site alteration.

Before an aperture is cut, it must be established that the existing door construction and its supporting evidence permit the modification and that the proposed ATG is suitable. 

Aperture size, position, installation detail and the competence of the person carrying out the work all need to be considered.

The permitted position depends on the fire door set and the evidence supporting the air transfer grille installation.

Fire testing may impose limits on the aperture's size and location, so the grille should not simply be positioned wherever it is most convenient. Always follow the relevant door set and ATG installation details.

Intumescent air transfer grilles generally have no moving parts, but they should still be included in routine inspection of the door, wall or ventilation system.

Check that the grille is secure, undamaged and unobstructed, and that no unauthorised alterations have been made to the grille or surrounding aperture.

Check that the grille and any cover are securely fitted and free from damage or obstruction. The surrounding aperture should also be checked for damage, unauthorised alteration or signs that the installation has been changed.

Any concerns should be assessed against the door set and grille documentation rather than relying solely on visual appearance.

Damage to an intumescent ATG could affect the performance of the fire-resisting installation and should not be ignored.

 The grille should be assessed and, where replacement is necessary, the new product and installation should be compatible with the existing door or wall and its supporting fire-performance evidence.

An acoustic door seal is designed to reduce airborne sound passing through the gaps around a closed door. Depending on the door set, acoustic seals may be fitted around the head and jambs, at the bottom of the door or between the leaves of a double door.

Different types of seal are often used together to create an effective acoustic sealing system.

Acoustic door seals work by closing the gaps through which airborne sound can travel around a door. Perimeter seals close gaps between the door leaf and frame, while door bottom seals prevent sound leaking through the gap beneath the door.

The effectiveness of the sealing system depends on factors including the door construction, seal selection, installation and how well the seals make contact when the door is closed.

Sound will find its way through surprisingly small gaps. An acoustic door therefore needs effective sealing around its perimeter and, where required, beneath the door to achieve the performance expected from the complete door set.

The door leaf, frame, seals, threshold and other components all contribute to acoustic performance. Specifying a high-performance door without accounting for the gaps around it can undermine the effectiveness of the overall assembly.

Sound can travel through gaps around the head and jambs of the door, beneath the door leaf and, on pairs of doors, through the meeting stile between the two leaves.

The gap beneath the door is particularly important because it must allow the door to operate freely while still being  effectively sealed when closed. Automatic drop seals are commonly used to address this.

Rw, or Weighted Sound Reduction Index, is a laboratory-measured value used to describe the airborne sound insulation performance of a building element or assembly. It is expressed in decibels (dB), with a higher figure indicating greater measured sound reduction.

When looking at acoustic performance figures, it is important to understand exactly what was tested. A seal should not be assumed to give any door the same Rw performance achieved by a particular tested door set or assembly.

Acoustic performance is established through laboratory testing of a defined specimen or assembly under controlled conditions. The resulting test data can be used to demonstrate the sound reduction achieved by that particular configuration.

When specifying seals, always look carefully at what has been tested, including the door construction, seal arrangement and other components. Acoustic performance should be considered as part of the complete door
set rather than attributed to an individual component in isolation.

The right acoustic seal depends on the door construction, required acoustic performance, door set configuration, and the gaps to be sealed.

A typical acoustic door set may require perimeter seals around the head and jambs together with an automatic drop seal or other door bottom seal. Double doors may also require an acoustic seal at the meeting stile. Where tested acoustic performance is required, products should be selected as part of a suitable door set or sealing configuration.

In some applications, yes. Sealing only the sides and head of the door leaves a gap beneath the door through which sound can continue to travel.

An effective acoustic sealing system therefore commonly combines perimeter seals with a suitable door bottom seal. The precise arrangement will depend on the door set and the required acoustic performance.

An automatic drop seal is a door bottom seal that remains retracted while the door is open and lowers automatically as the door closes. The seal makes contact with the floor or threshold, closing the gap beneath the door.

When the door opens, the seal retracts again, allowing the door to swing freely without the sealing element continually dragging across the floor.

Automatic drop seals are useful where the gap beneath a door
needs to remain clear while the door is opening and closing but sealed when the
door is shut.

They are commonly used in acoustic door sets. They can also form part of doors designed to control smoke, fire, or draughts, depending on the product's tested performance and specification.

A perimeter seal closes gaps between the door leaf and frame, normally around the head and vertical jambs. A drop seal is fitted at the bottom of the door to seal the gap between the door leaf and the floor or
threshold when the door closes.

They perform different jobs and are frequently used together as part of an acoustic sealing system.

Not always. Whether a threshold plate is required depends on the drop seal, floor surface, gap and required performance.

A smooth, consistent surface can help a drop seal make effective contact across the full width of the doorway. Where the floor is uneven, carpeted or otherwise unsuitable, a threshold plate may provide a more reliable sealing surface. Always follow the recommendations for the particular drop seal and door set.

They can, but compatibility with the fire door set must be established rather than assumed. Adding or replacing components on a fire door can affect its tested or assessed performance.

Where an acoustic seal is required on a fire-resisting door set, the seal and installation arrangement should be supported by appropriate evidence for the application. The fire door manufacturer's information and relevant test or assessment evidence should always be checked.

Yes, acoustic seals are available for different door constructions, including timber and metal doors. The fixing method, dimensions, and appropriate seal arrangement may, however, differ.

The seal should therefore be selected for the particular door construction and required performance rather than assuming that the same product or installation detail is suitable for every door set.

Double doors introduce an additional potential sound path where the two door leaves meet. In addition to perimeter and door bottom sealing, the meeting stile may therefore need a suitable acoustic seal.

The exact arrangement will depend on the door configuration, including whether the leaves are rebated or square-meeting, and the required acoustic performance.

Yes, there are acoustic drop seals and sealing systems designed specifically for glass doors. Product selection will depend on factors including glass thickness, door configuration, and the required acoustic
performance.

Glass doors require seals and fixing methods suited to that construction; a product designed to be morticed into a timber door should not simply be treated as interchangeable with a glass-door system.

Acoustic door seals should be installed in accordance with the manufacturer's instructions and the details of the tested or specified door set.

Correct positioning is important because acoustic sealing depends on continuous, effective contact. Poorly fitted, damaged or incorrectly adjusted seals can leave small gaps that allow sound to pass through.

Very. Gaps around a door provide a direct route for airborne sound and can significantly affect the performance of the complete door set.

Good acoustic design therefore considers the gaps at the head, jambs, threshold and meeting stiles, rather than concentrating solely on the construction of the door leaf.

One common method is an automatic drop seal fitted to the bottom of the door. As the door closes, the seal lowers to contact the floor or threshold, closing the gap. It retracts again when the door opens.

The appropriate solution will depend on the door set, floor or threshold condition, required clearance and acoustic performance.

This varies between products. Automatic drop seals have a specified maximum drop or adjustment range, and the product must be selected to suit the gap beneath the particular door.

A larger drop is not necessarily better. Correct installation and consistent contact across the threshold are important, so the
manufacturer's stated dimensions and adjustment instructions should always be
followed.

An automatic drop seal needs to make effective contact with the floor or threshold when the door is closed to close the acoustic path beneath the door.

The aim is consistent sealing across the width of the opening without excessive pressure. Incorrect adjustment can leave gaps or place unnecessary pressure on the mechanism.

Some automatic drop seals incorporate mechanisms designed to compensate for variation across the floor or threshold. However, there are limits to what the seal can accommodate.

Significant irregularities may prevent continuous contact and affect acoustic performance. 

In these situations, a suitable threshold plate or other adjustment to the interface may be required.

Yes. Acoustic performance depends on the complete door set and the continuity of the sealing system. Incorrect positioning, poor adjustment, damaged seals or gaps at junctions can all create routes for sound leakage.

Following the specified installation details is therefore just as important as selecting the correct acoustic seal.

There isn't a single dB figure that applies to every acoustic door seal in every application. Performance depends on the seal, door construction, gaps, threshold, and how the complete assembly has been tested.

Published acoustic figures should therefore be read alongside the associated test evidence so that specifiers can understand the configuration in which that performance was achieved.

No. Adding an acoustic seal to a standard door does not automatically give the complete door set a particular acoustic rating.

Acoustic performance relates to the complete assembly and its construction, including the door leaf, frame, seals, threshold and installation. Where a specific Rw performance is required, the door set and sealing arrangement should be selected using appropriate test evidence.

Acoustic door seals are generally low maintenance, but they should still be inspected as part of routine door maintenance.

Check that the seals are clean and undamaged, and that they make continuous contact when the door is closed. Moving components, such as
automatic drop seals, should also be checked to ensure they operate and retract correctly.

There is no single lifespan for every acoustic door seal. Service life depends on the type of seal, frequency of use, installation, environment and the amount of wear or damage it experiences.

Regular inspection is more useful than relying on an assumed replacement interval. A seal that is damaged, worn or no longer making effective contact should be investigated and replaced where necessary.

Visible damage, distortion, missing sections or loss of contact with the door or frame can indicate that a seal is no longer performing as intended.

For automatic drop seals, also check that the mechanism operates smoothly and that the sealing element makes consistent contact across the threshold when the door closes.

Sound leakage can have several causes. There may be gaps around the perimeter or beneath the door; an automatic drop seal may be incorrectly adjusted; seals may be damaged; or the meeting stile on a pair of doors may not be adequately sealed.

The problem may also lie elsewhere in the door set or surrounding construction. Acoustic performance should therefore be assessed as a complete system rather than assuming the door seal is always responsible.

A gap between the sealing element and the floor or threshold creates a potential path for sound transmission. The first step is to check the seal's adjustment and installation against the manufacturer's instructions.

The condition of the threshold should also be checked. An uneven surface or incorrectly sized gap may prevent the seal from making consistent contact across the opening.

Many automatic drop seals provide an adjustment so the seal can be set to make proper contact with the floor or threshold.

The adjustment method and permitted range vary between products, so the manufacturer's instructions should always be followed. Over-adjusting the seal can be just as problematic as leaving insufficient contact.

Many automatic drop seals provide an adjustment so the seal can be set to make proper contact with the floor or threshold.

The adjustment method and permitted range vary between products, so the manufacturer's instructions should always be followed. Over-adjusting the seal can be just as problematic as leaving insufficient contact.

No. A fire door must be a properly tested construction. Simply adding a fire seal doesn't convert a standard door into a certified fire door.

Installing a tested retrofit cold smoke seal is the simplest method. These seals are easy to install and don't require door removal. 

No. Substituting seals can compromise the door's fire performance. Always use the seal type and size specified in the test evidence. 

No. Different intumescent materials activate at varying temperatures. It's crucial to use the same material that was used in the original fire test to ensure compliance and effectiveness. 

Yes, intumescent strips can be fitted to regular doors. However, ensure the door and seal combination meets the required fire safety standards. 

We aim to deliver orders placed before 16:30 on the next working day, with delivery before noon as standard.

Yes. Deliveries to Ireland, the Scottish Highlands, and other remote areas may incur additional charges, may not qualify for free shipping, and might use an alternative shipping company. Customers will be notified of the alternate shipping company when placing their order. 

If goods are damaged during transportation, customers are entitled to replacement goods. However, the damage must be reported to us within 24 hours of delivery. 

Customers can track their orders in real-time through our online portal. The portal provides access to live order statuses, including whether an order has been dispatched, is in progress, or on hold. 

If you receive goods that are faulty or defective, you must notify us within 5 days of discovering the defect, and within 90 days of delivery. The defective goods should be returned to Norseal at your expense. 

Yes. If the goods were manufactured by Norseal and are found to be defective due to faulty design, materials, or workmanship, Norseal will, at its discretion, repair or replace the goods free of charge. 

In such cases, any warranty granted to Norseal by the third party will be passed on to you. 

Yes. Norseal is not liable for any loss (including loss of profit), costs, damages, charges, or expenses incurred by you, or for any loss or damage to or caused by the goods, except as provided under their terms of sale.