Underfloor Heating Under Carpet: UK Guide
You can install underfloor heating under carpet, but carpet insulates the heat so efficiency drops significantly.
UFH works under carpet if total tog rating (carpet + underlay) is under 2.5. Use thin underlay and loop-pile carpet. Heating efficiency drops 30–50% vs tile. Running costs increase. Not recommended unless you're committed to carpet flooring.
Tog rating explained
Tog measures thermal resistance (insulation). Higher tog = more insulation = less heat reaches the room.
UFH manufacturers recommend max 2.5 tog total (carpet + underlay combined). Above that, too much heat is blocked.
Typical values:
- Tile: 0 tog (no insulation)
- Engineered wood: 0.15 tog
- Thin carpet: 1.0–1.5 tog
- Thick carpet: 2.0–2.5 tog
- Standard underlay: 1.0–1.5 tog
- Thick underlay: 2.0–3.0 tog
Best carpet for UFH
Choose:
- Loop-pile carpet (lower tog than cut-pile)
- Thin carpet (under 1.5 tog)
- Rubber-back carpet (no separate underlay needed)
- UFH-approved underlay (under 1.0 tog, often foam or rubber)
Efficiency loss
Carpet under UFH reduces efficiency by 30–50%. You'll use more energy (higher bills) for the same room temperature. A room that costs £200 per year to heat with tile will cost £300–400 per year with carpet.
Alternative
If you want soft flooring with UFH, consider LVT (feels warmer underfoot than tile, transfers heat well, 0.1 tog).