A Guide to Fitting Intumescent Grilles

Intumescent grilles, or air transfer grilles, are a great way to add ventilation in a fire door, wall or floor without compromising the fire integrity of the application. However, it’s crucial that they are installed correctly to ensure they function properly in the event of a fire. 

There are a huge number of different ways to install intumescent grilles depending on the application and so it’s important to always consult the specification to ensure it’s being installed correctly. 

Below, we’ve picked out some of the most common placements for intumescent grilles and how they should be installed. 

Fitting an Intumescent Grille in a Timber Fire Door

Air Transfer Grille to use: LVV40

Important notes:

• The upper edge of the grille shouldn’t be any higher than 3000mm from the floor in order to comply with CF564
• The lower edge of the grille shouldn’t be any closer than 400mm to the floor
• Consult your door manufacturer before cutting the aperture needed, to ensure the size and location on the door is in line with their testing

Products needed:

• LVV40 ATG
• Cover grilles (optional)
• Power drill
• Screw driver
• 25mm wood screws
• Lorient intumescent sealant 

Instructions:

• Cut the aperture required for the ATG, with a maximum gap of 3mm all the way around
• Apply Lorient intumescent sealant to the inside edges
• Fit the LVV40 and make sure it’s of equal distance from each side and parallel
• Fit retaining wood screws through the pre-drilled holes
• Clean off any surplus sealant and make sure the outer edges are fully sealed
• If using cover grilles, position in place and fix using 25mm wood screws on either side

Fitting an Intumescent Grille in a Rigid Wall

Air Transfer Grille to use: LVV40

Important notes:

• The upper edge of the grille shouldn’t be any higher than 3000mm from the floor in order to comply with CF564
• The lower edge of the grille shouldn’t be any closer than 400mm to the floor

Products needed:

• LVV40 ATG
• Cover grilles (optional)
• 50mm screws
• Wall plugs for 50mm screws
• Lorient intumescent sealant

Instructions:

• Cut the hole required for the ATG ensuring a maximum gap of 5mm all the way around
• If the hole created isn’t square, or is irregular or oversized, you can use mortar to amend it
• Position the LVV40 in the aperture created and make sure it can be positioned in the mid section of the wall easily
• Mark the drill points in the wall either side of the ATG and remove the grille from the wall
• Fix a minimum of 4 screws through the side wall
• Position the LVV40 in place and fix the screws on the closest side
• Bed in sealant around the grille and clean off any surplus ensuring the outside edges are fully sealed
• If using, add the cover grilles and fix using the wall plugs

Fitting an Intumescent Grille in a Flexible Wall

Air Transfer Grille to use: LVV40

Products needed:

• LVV40 ATG
• Cover grilles (optional)
• Drywall screws (3.5 x 42mm)
• Lorient intumescent sealant

Instructions:

• Cut the hole required for the ATG ensuring there’s a maximum gap of 5mm all around
• Frame in the opening to support the grille
• Ensure the final aperture is square and the correct size
• Position the LVV40 in the aperture created and make sure it can be positioned in the mid section of the wall easily
• Mark the drill points in the wall either side of the ATG and remove the grille from the wall
• Fix a minimum of 4 screws on the one side of the markings to press the grille up against
• Position the LVV40 in place and fix the screws on the other side
• Bed in sealant around the grille and clean off any surplus ensuring the outside edges are fully sealed
• If using, add the cover grilles and fix using the dry wall screws.

Fitting an Intumescent Grille in a Masonry Floor with Angle Fixings

Air Transfer Grille to use: LVH44

Products needed:

• LVH44 ATG
• Cover grilles (optional)
• Masonry anchors
• Angle fixings 40 x 20 x 1mm
• Lorient intumescent sealant

Instructions:

• Fix mounting angles to the floor using masonry anchors to one side only
• Insert the ATG into the floor aperture
• Apply bead of sealant around perimeter of metal sleeve
• Connect ductwork or cover grille directly to floor using approved breakaway connections to ensure compliance. 

*If ductwork doesn’t extend above the floor, a protective and load-bearing grate is necessary.