You are here:

Fire mortar

Product 6


Intumescent fire mortar to provide a load-bearing fire seal in floors and walls

Not available to purchase online.

We need to ask you a few more questions and ensure this is the suitable product for your needs.

To order please call us on +44 (0) 1 304 842 555

£0.00 ex. Vat


Fire Mortar

An asbestos-free dry mix, add water and then mixed like plaster. Shuttering boards are not required. Lay Rockwool slabs into the opening, leaving the required depth for the mortar. Upon setting, the mortar is load-bearing. Also, you can use wood bits to drill for the installation of services.

Used in conjunction with either intumescent slabs or also non-fibrous slabs, the mortar provides a permanent fire stopping solution for load-bearing floors, walls and ceilings. For areas over 600 x 900mm, it’s essential to reinforce with 30mm chicken wire mesh, fixed with FB/C straps and support battens. Refer to the Technical Data Sheets for full details of the correct installation of mortar.

Additionally, in the case where pipes, services or cables pass through the surface of a wall or floor, it is essential to fit Intumescent Wraps, Firoblok or Intumescent Collars to reinforce fire protection.

Available in dark grey.

  • IMPORTANT – This product is for use with intumescent slabs (Products 4 or 5) and must not be used by itself
  • Can be used on fire-rated timber, plasterboard, concrete walls and brick, block or concrete floors

Fire barriers provide an effective solution for gaps as well as voids within buildings that require fire protection. Browse our full range of fire barrier products.


– Great for fire-stopping around building services that pass through floors

– Can be used on fire rated timber, plasterboard, concrete
walls and brick, block or concrete floors
– Acts as permanent shuttering around services, filling apertures in walls and floors
– The following fire ratings can be achieved with the corresponding thickness:
– Up to 6-hour protection: 100mm
– 4-hour protection: 25mm
– 3-hour protection: 12mm
– 2-hour protection: 6mm
– 1-hour protection: 3mm
IMPORTANT – This product is for use with intumescent slabs (Products 4 or 5) and must not be used by itself

Application Instructions

For the 25 kg bag, add 4 ¼ to 4 ¾ litres of water, and mix like plaster. For floors,
pour into the floor opening. For walls, apply over a Rockwool Slab with a trowel or
float. 25 kg bag will fill approx. 8600 cm³ or 2 bags will fill 0.83 m² to depth of 25 mm.

Application into floor: For openings 600 mm x 900 mm, no wire mesh is required. Just
fit Rockwool slab, fit Envirograf Protection around any services and fill over the Rockwool
to the required depth, with the FM Fire Mortar. For larger openings, fit 50 mm RW4 or
RW6 Slab where large areas over 1 metre wide, use Envirograf® Ref: SUP Support
Bars (As Picture) under Rockwool. Fit 30 mm wire mesh over the Rockwool, cutting
around services and wiring to the services. Fix wire mesh all around the perimeter of
the hole, bend up the wall or floor and fit with Envirograf® FB/C Metal Battens to
support the mesh.
Fit Envirograf® Fire Protection Wraps around pipes and electrical services,
Intumescent Pads inside and Trunking Pillows for Cable Trays. Product 40 Fire Proof
Sponge around ventilation trunking. Then mix FM Fire Mortar and pour into the
opening to the required depth.

Order References / Sizes


FM25                      25 kg regular fire mortar GREY-coloured

SUP                        Metal Support Batten for large floor openings (see illustration top of page), price per metre

MESH                   30mm wire mesh x 1200mm width, sold per linear metre run