Cormar Primo Tweeds (1.2 TOG) with Cloud 9 Super Contract (2.1 TOG) gives a combined 2.3 in-situ TOG. Whether that passes the 2.5 TOG underfloor heating limit and what to do.
Updated 05 September 2026.
Cormar Primo Tweeds and Cloud 9 Super Contract: combined TOG for underfloor heating
The combined TOG for Cormar Primo Tweeds over Cloud 9 Super Contract, 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 Primo Tweeds (1.2 TOG) |
|---|---|
| Underlay | Cloud 9 Super Contract (2.1 TOG) |
| Published sum | 3.3 TOG |
| UHMA in-situ correction | minus 1 TOG |
| Combined in-situ TOG | 2.3 TOG |
| Standard UFH limit | 2.5 TOG |
| Heat pump target | under 1.5 TOG |
Cormar Primo Tweeds is rated 1.2 TOG and Cloud 9 Super Contract is rated 2.1 TOG. Laid together the combination is what the underfloor heating has to warm through.
The published TOG figures add to 3.3. The UHMA rule subtracts 1 TOG because tests showed real in-situ resistance runs about a TOG below the paper sum, giving 2.3 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 Primo Tweeds and Cloud 9 Super Contract: combined TOG for underfloor heating?
Combined in-situ TOG is 2.3, under the 2.5 TOG limit, so Cormar Primo Tweeds with Cloud 9 Super Contract 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.