Acoustic Letterplate by Norsound

  • • 30,000 cycle test
  • • Royal Mail standards for A4 post
  • • Salt spray tested to BS EN 1670
  • • Sound reduction up to 54dBRw
  • • Up to 60 minutes fire rated
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Norsound’s NOR400 acoustic letter plate comes acoustically tested up to 40dB whilst also being fire resistant up to 60 minutes.

Outstanding acoustic performance means the NOR400 is the perfect choice for flats or houses near busy roads. It has been salt spray tested up to 480 hours - which follows the European standard BS EN 1670: Grade 5. Use this letterplate with a restrictor piece or security cowl (optional extras) to comply with PAS 24. It has also been tested within a doorset to comply with PAS23 and cycle tested for use up to 30,000 cycles.

The NOR400 has been specifically designed to rectify the problem of unwanted sound being transferred in doors where cutting a hole in the centre of the door for a letter plate is a necessity. Previously this may have caused significant damage to the soundproofing of the door set but the NOR400 aims to protect its acoustic properties.

Available in gold as well as satin and polished chrome, this high quality letter plate is the perfect solution for those wanting to not only secure a fire door but are also concerned with keeping unwanted sound to a minimum. Other finishes are available via special order, including 'graphite', black, white, bronze, antique black and silver.

Size Colour Code
12" Gold NOR400/GLD
12" Satin chrome NOR400/SC
12" Polished chrome NOR400/PC
An acoustic, fire-rated letterbox? Is it really necessary?

After spending the time looking for, then specifying the right combination of seals to get the optimal decibel reduction and fire ratings for your door system, cutting a hole to fit a standard letterbox would seriously compromise the acoustic and fire-rated properties.

To remedy this, the NOR400 is cleverly designed to provide an effective smoke and acoustic seal, whilst the included intumescent liner maintains the integrity and rating of a 60 minute fire-rated door.

Do I need anything else with this product to fit it?
An intumescent mastic is a necessity in fitting this product. A tube of either the NOR115 Acoustic fire rated mastic or the Fire Wizard intumescent mastic would be suitable and can also be bought from us.
What aperture size shall I cut to house this product in the door?
We recommend against cutting out a hole in your door until receiving the Norseal Advantage letter plate. This is because the liner surrounding the product will cause the raw dimensions of the letter plate’s centre part to be inaccurate, and often there won’t be an exact figure for the size including liner.
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