Envirograf Intumescent Letter Box Units
  • Envirograf Intumescent Letter Box Units

Envirograf Intumescent Letter Box Units

Product 49

Intumescent Letter Box Units provide fire protection on doors for businesses and homes. The fireproof letterbox unit protects against fire and smoke for up to 1 hour; lockable letter flaps are available allowing the rear of the fire rated letterbox to be fastened shut, preventing materials from being posted through with the intention of starting a fire.

  • Anti arson letterbox units for doors
  • Ideal for areas where the threat of vandalism and arson is real
  • Up to 1 hour of fire protection
  • Lockable letterplates available
  • Available in 3 sizes, fitting doors from 36mm to 70mm thick
  • Tested to European Standard EN1634-1 (2000)
  • Meets BS476 Part 22 1987 criteria
  • Choose a size and colour from the drop-down menus below, or call us on 0113 2455450 for more information.
VAT excluded

£43.10 Tax incl.


Envirograf Intumescent Letter Box Units offer fire and smoke protection to doors for up to 1 hour. The fireproof letterbox is ideal for homes and businesses, especially those in areas with a real threat of arson and vandalism, as well as flats and apartments to prevent spread of smoke and flames into escape routes. Available in 3 sizes, the anti arson letterbox  fits doors from 36mm to 70mm thick.

Lockable letterplates are also available from the drop-down menu above - fitting these to the back of the fire rated letterbox allows it to be locked from the inside, preventing materials that have been set on fire from being pushed through and potentially igniting furnishings and fittings.

For more information about this product's details, Test Data and Test Results included in manufacturer attachments, please contact our Technical Support team on 0113 245 5450, or send us a message here.

Order References & Sizes

Type Hole Size Overall Size
L1 - L4 50 x 267mm 75 x 315mm
L6 - L8 69 x 290mm 100 x 335mm

Option A: Front smoke frame and flap + intumescent liner.

Option B: Front smoke frame and flap + intumescent liner + rear smoke frame and flap.

Option C: Front smoke frame and flap + intumescent liner + security hood (standard security hoods are black).

Colour Ref Ref Ref
Brown L1A L1B L1C
White L2A L2B L2C
Stainless L3A L3B L3C
Brass L4A L4B L4C
Coloured L6A L6B L6C
Stainless L7A L7B L7C
Brass L8A L8B L8C

Special BS and RAL colours made to order at an extra charge - please call our sales team on 0113 2455450 for more information.


Lockable Letter Plates

Ref Colour Aperture Size External Size
LLP1 White 260mm x 40mm 310mm x 70mm
LLP2 White 275mm x 60mm 335mm x 100mm


Lockable Letter Plates (With Key Holder)

Ref Colour Aperture Size External Size
LLP3 White 260mm x 40mm 310mm x 70mm
LLP4 White 275mm x 60mm 335mm x 100mm


New Letter Box Unit

Complete with intumescent liner. Overall size 76mm x 310mm, deep to suit doors 38-60mm.

Ref Colour
DLP/BC Bright Chrome
LP/SC Satin Chrome
LP/BRS Brass
LP/WH White


Internal Smoke Flap

Consists of a 10mm deep metal surround, with a metal flap, housing a smoke and draught seal to suit hole 267 x 50mm. These are made in the standard colours shown below:

Ref Colour
SM/S Black/Brown/White
SM/S Stainless Steel (with black surround)
SM/S Brass
SM/LIN Intumescent Liner

Examples of Use

The Metropolitan Police advise that enclosed properties are more likely to be targeted for vandalism and arson attacks. High walls and fences will shield an intruder from view, giving them more time to act, with unlit areas hiding snoopers at night.

Recommendations include keeping walls, fences and hedges to a metre high so your property can be seen from the street and by neighbours, adequate dusk-til-dawn lighting that leaves no hiding places and, of course, fireproof letterboxes.


This product has been included in a fire test employing the general procedures and criteria of BS476 Part 22 1987, built into a composite door, maintaining the integrity of the door for 61 minutes. Also tested to European Standard EN1634-1 (2000), achieving 68 minutes.


Insert the Letter Box Unit into the hole and fix with screws supplied; insert the liner to finish and then fix with double sided tape and pins supplied.

For Internal Flaps / Security Hoods, align with the external flap and fix with screws supplied.

Material Specification

Multigraf Intumescent material chemical constitution

  • Mineral Wool Fibre 20-70% by weight
  • Exfoliating Graphite 20-60% by weight
  • Organic Binder (including adhesive coating) 5.0-30% by weight

Test Details

Test Integrity Insulation
Efectis 2008-Efectis-R04468 68 Minutes 68 Minutes
LPC TE82291 61 Minutes 14 Minutes
Chiltern RF97033 51 Minutes 51 Minutes

IMPORTANT FIRE PRODUCTS NOTICE: The information displayed on this website should be used as a guide ONLY and our Technical Department should be contacted to obtain a tailored specification and any advice necessary before you place an order for fire protection products. Fire protection products are non-returnable except in accordance with Condition 8 of the Terms and Conditions. We will not be held liable for any resulting damage to property, human life or monetary costs incurred due to the incorrect specification you have prepared or use of fire protection products caused by your negligence, including your failure to have contacted us to obtain the relevant advice/specification.

Any Envirograf products to be used in or for Harrods department store should be authorised with our Technical Team prior to purchase.

It is your responsibility to read the Product Data Sheets (available below) before you place an order and prior to application of the product. The content of this website is our best recommendation and is not advice. Coverage rates quoted are approximate, you agree that coverage depends on the condition of the substrate, surface absorption, texture and application method. We ALWAYS recommend a trial area is coated to ensure the product meets your requirements before use.

Product Details
Product 49

Customer agrees that before placing an Order, Customer has read and understood the most up to date Product Data Sheet for the Product. Where we have access to the Product Data Sheet from the manufacturer, we will either provide a copy on request, or include a link to the Product Data Sheet available on the manufacturer’s website. Customer further agrees that we have no liability for any errors or omissions contained within the Product Data Sheets. For more information, please see our Terms & Conditions of Sale.

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