Cormar Trinity (1.6 TOG) with Tredaire Colours Green (1.47 TOG) gives a combined 2.07 in-situ TOG. Whether that passes the 2.5 TOG underfloor heating limit and what to do.
Updated 05 September 2026.
Cormar Trinity and Tredaire Colours Green: combined TOG for underfloor heating
The combined TOG for Cormar Trinity over Tredaire Colours Green, worked against the UHMA underfloor heating rule.
Combined against the UHMA 2.5 TOG underfloor-heating limit. Under 1.5 also suits a low-temperature heat pump.
| Carpet | Cormar Trinity (1.6 TOG) |
|---|---|
| Underlay | Tredaire Colours Green (1.47 TOG) |
| Published sum | 3.07 TOG |
| UHMA in-situ correction | minus 1 TOG |
| Combined in-situ TOG | 2.07 TOG |
| Standard UFH limit | 2.5 TOG |
| Heat pump target | under 1.5 TOG |
Cormar Trinity is rated 1.6 TOG and Tredaire Colours Green is rated 1.47 TOG. Laid together the combination is what the underfloor heating has to warm through.
The published TOG figures add to 3.07. The UHMA rule subtracts 1 TOG because tests showed real in-situ resistance runs about a TOG below the paper sum, giving 2.07 TOG. On a heat pump running low flow temperatures the floor has less heat to push, so aim under 1.5 TOG and prefer the thinnest underlay in this range.
Questions and answers
Cormar Trinity and Tredaire Colours Green: combined TOG for underfloor heating?
Combined in-situ TOG is 2.07, under the 2.5 TOG limit, so Cormar Trinity with Tredaire Colours Green is suitable for a standard underfloor heating system. It is above 1.5 TOG, so on a low-temperature heat pump run choose a thinner underlay.