How to fit a downlight fire hood

Helpful video reference. John Ward (jwflame) covers the topic well in his video "Downlights, Fire Rating, Fire Hoods & Loft Covers", published on his flameport.com channel. He explains the difference between fire-rated and non-fire-rated fittings clearly, including when a separate hood is and is not required. Good background to read alongside this guide before you go near the ceiling.

1. Check whether your downlight actually needs a fire hood

Not every recessed downlight needs a separate fire hood. The question is whether the ceiling it sits in forms a fire separation between one floor and another.

• Ground floor ceiling, living space above -- the ceiling is a fire separation. A non-fire-rated downlight needs a hood.
• First floor ceiling, cold loft above -- Building Regulations Part B fire-compartmentation does not apply at the loft floor in the same way. A fire hood is not required for fire purposes here, though a thermal loft cover may be sensible to manage heat around the fitting and reduce draughts.
• Fire-rated downlight -- if the fitting body carries a printed fire rating (30, 60 or 90 minutes) it has integrated intumescent protection and needs no separate hood. Check for the rating mark before ordering anything.

If in doubt, fit the hood. It does no harm to add one where it is not strictly required, and it costs very little.

2. Choose the right fire hood

Measure the aperture diameter: most UK LED downlights use a 70 mm or 75 mm cut-out. The hood must match that dimension so the skirt sits flat on the upper face of the ceiling board with no gaps at the edges.

There are three main types on the market:

• Rigid plastic bag type (like the Tenmat or similar) -- a sealed polythene box with intumescent seals at cable entry points. Push it down through the aperture, cable entry points facing up, then clip it to the ceiling board above.
• Expanding foam pad type -- a foam disc that sits on top of the fitting body and expands in the heat of a fire to seal the aperture. Simple to fit but you must ensure the disc covers the full aperture diameter.
• Mineral wool or glass-fibre hood -- a rigid or semi-rigid cup lined with fire-resistant mineral wool. Heavier than plastic types but effective and often rated to 60 or 90 minutes.

Buy from a manufacturer whose hood carries a tested fire resistance rating to EN 1363-1 or BS 476. Cheap unbranded hoods with no test data are a false economy on a fire safety product.

3. Isolate the circuit

Go to the consumer unit, identify the lighting circuit for the floor you are working on, and switch it off. Write a note or lock out if anyone else is in the property. Test the downlight fitting with a voltage tester before you touch it. Dead at the switch? Good -- carry on.

4. Remove the downlight fitting

Spring-clip types pull straight down once you squeeze the two clips inward. Twist-and-lock types rotate anti-clockwise about 30 degrees and then drop. Ease the fitting clear of the aperture but let it rest below the ceiling -- you do not need to disconnect the flex connector unless the fire hood specifically requires you to pass the cable through a grommet.

5. Fit the fire hood through the aperture

For a rigid bag-type hood, compress it slightly and pass it up through the aperture from below. Once above the ceiling, release it and push it down until the skirt sits flat on the upper face of the plasterboard. Route the existing downlight flex through the cable-entry grommet on the hood so the cable is inside the sealed enclosure.

For foam-pad types, simply place the pad over the top of the fitting body before refitting it into the aperture. The pad sits between the fitting body and the ceiling board above.

If you have loft access, go up and check the hood from above. The skirt must sit flat with no visible gaps at the ceiling board. Make good any large gaps with intumescent mastic -- fire hoods are only as good as their contact with the ceiling surface.

6. Check insulation clearance

This catches people out. Many fire hoods require a clear air gap of at least 50 mm around the outside of the hood body -- you cannot pack mineral wool insulation tight against them. If the loft has been recently insulated, you may need to pull the insulation back from each hood position.

Some products (Thermahood and similar combined fire-and-thermal units) are specifically rated for full insulation contact and can be buried under quilt insulation. Check your specific product's datasheet before deciding either way. Do not assume -- the answer varies by brand and model.

7. Refit the downlight and restore power

Reconnect the flex connector if you disconnected it. Push the downlight back into the aperture and re-engage the spring clips or rotate it clockwise to lock. Restore power at the consumer unit and switch the light on. Leave it running for a few minutes and confirm there is no unusual smell or discolouration around the ceiling. A fitting that overheats after a hood is fitted may need a different downlight with a lower thermal output.

When to call us

Fitting a fire hood is well within the capability of a careful homeowner once the circuit is isolated. Where to stop and call is when the job reveals older wiring than expected, when a fitting has clearly been running too hot, or when you want a qualified inspection to confirm all the downlights on a floor are correctly protected. Richard covers Sandwich and east Kent and can inspect a full floor of downlights on a small-job rate.