Envirograf Intumescent Fire Bags and Boxes
  • Envirograf Intumescent Fire Bags and Boxes

Envirograf Intumescent Fire Bags & Boxes

Product 52

Intumescent Fire Bags & Boxes provide fire protection for letterboxes, particularly in areas with a real risk of vandalism or arson, fitting to the interior of a letterbox and work by extinguishing ignited items dropped through a door with the intention of starting a fire. Our fireproof letterbox bags fit both horizontal and vertical letterboxes, whilst the metal boxes are fitted with hinged, lockable lids and can be custom made with chutes and spouts to pass through walls, if required.

  • Refer to sizes below
    • Fire Bags only available in white
  • When ordering two or more rigid metal boxes, please state if matching keys are required for all boxes on that order
  • Boxes include a hinged lid and a lock
  • Fit to the back of a letterbox for extra letterbox fire protection
VAT excluded

£107.23 Tax incl.


Order References:

Flexible bags with horizontal letter opening:

Available in white

Ref Wall/Door Height Outside Height Depth Width  
FLEX1 335mm 335mm 130mm 420mm Aperture size 315mm x 70mm
FLEX2 335mm 335mm 130mm 420mm For UPVC Doors. Aperture size 330mm x 55mm, Single layer of cloth.
FLEX3 260mm 260mm 95mm 400mm For UPVC doors. Aperture size 290mm x 55mm
FLEX3/A 260mm 260mm 95mm 400mm For UPVC doors. Aperture size 315mm x 70mm


Flexible bags with vertical letter opening:

Available in white

Ref Wall/Door Height Outside Height Depth Width  
FLEX4V 560mm 560mm 130mm 360mm Aperture size 315mm high x 70mm wide.
FLEX5V 530mm 530mm 100mm 300mm Aperture size 290mm high x 55mm wide.


Rigid metal boxes:

Available in white, black or brown.

When ordering two or more rigid metal boxes, please state if matching keys are required for all boxes on that order.

The rigid metal boxes are supplied with hinged lids and flush locks. Other colours and sizes can be made to order, with front-opening doors and recessed locks optional. Chutes and spouts can also be made to order for passing through walls.

Ref Wall/Door Height Outside Height Depth Width
FB1 360mm 300mm 170mm 375mm
FB2 360mm 300mm 90mm 375mm
FB3 360mm 300mm 200mm 400mm
FB4 675mm 600mm 300mm 600mm

For all queries and custom orders, please contact our sales team on 0113 245 5450.


Envirograf Intumescent Fire Bags & Boxes fit to the back of letterboxes, working by extinguishing ignited items that are dropped through intending to start a fire. Ideal for properties in areas threatened with a real risk of arson or vandalism, such from businesses to homes, the range includes fireproof letterbox bags for both horizontal and vertical letterboxes and more rigid, metal fireproof boxes with hinged, lockable lids that can be custom-fit with chutes and spouts to pass through walls. The anti arson letterbox bags are great for doors with limited space behind when opened, offering minimal distruption whilst protecting your letterbox.

Key Features

  • Fireproof bags and boxes for letterboxes in doors
  • Fits to the back of doors for extra fire protection
  • The anti arson letterbox bags are available for horizontal and vertical letterboxes
    • Great for doors with limited space behind
  • Use in areas threatened by arson or vandalism
  • Great for businesses and homes alike
  • Metal fireproof letterbox boxes are supplied with a hinged, lockable lid
    • Can be custom-fit with a chute or spout for passing through walls

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.

King Street Bus Station in Mildenhall, Suffolk, uses fireboxes on litter bins housed in its modern architectural design, guarding against accidental or malicious fires caused by burning cigarette butts, arson or vandalism.


Metal Boxes:

Simply screw into position using 30mm screws

Flexible Fire Bags:

The Flexible Fire Bag has an oversized letterbox opening to go over existing internal openings
or flaps. The pack is supplied with a small tube of Fire Proof Silicone, which can either be
squeezed over the external plate or around the internal side of the door, around the letterbox
opening. Open the lid by turning the clips and separating the Velcro tape. There are two holes
at either end of the metal plate, simply screw to the door with the screws supplied.


Please ensure that the lid is sealed again every time after it has been opened

Material Specification:

Woven Glass Fabric (Flexible bag)

  • Thickness - 0.40mm Wt/m² - 430 g/m²
  • Warp count - 1360 d'tex
  • Finish - Starch weave lock

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

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 ConditionsWe 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 52

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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