Cutting a hole in a ceiling for a downlight punches a hole in the fire compartment between two floors. Building Regulations Part B (Fire Safety) requires that penetration to maintain the fire rating - usually 30 minutes for a domestic first-floor ceiling. That is what a fire-rated downlight hood does.
What "fire-rated" actually means
The hood is an intumescent enclosure around the light fitting from above. In a fire, it expands and seals the hole. Without it, flames pass through the cutout into the ceiling void within minutes and jump between rooms and floors far faster than they otherwise would. Every downlight over a habitable room - bedroom below, sitting room below, any room where people sleep or spend time - gets one.
Thermal cutout
The other reason for the hood is thermal. LED downlights run cooler than halogen but the driver still generates heat, and covering the fitting with loft insulation from above is a fire risk without a hood. The hood keeps insulation off the fitting and prevents overheating.
Thatched properties
In a thatched roof, the whole game changes. We do not put downlights in a thatched-ceiling room at all, ever. The insulation-plus-driver-plus-thatch stack is a fire waiting to happen, no matter how good the hood is. Wall lights, pendant fittings, table lamps. Not downlights.
Position and spacing
- Standard spacing: 1.2 to 1.5m centres for general lighting.
- Do not put downlights over a bed, sofa or reading chair - they glare. Use wall lights or table lamps for those positions.
- Kitchen: downlights over worktops and preparation areas, pendant over the island or table.
- Bathroom: IP65-rated fittings in Zone 1 (the shower cubicle) and Zone 2 (600mm outside the bath or shower), IP44 elsewhere.
Dimming and colour temperature
2700K warm white as domestic default. Dimmable driver as standard. Non-dimmable saves £3 per fitting and costs you the room. Compatible trailing-edge dimmer at the switch or (better) a scene keypad on DALI or Casambi.
Retrofit tip
If your existing halogen downlights do not have hoods, you can retrofit fire-rated LED downlights with integral hoods as a straight swap. Same hole, better fitting, and you gain the fire compartmentation you did not know you were missing.