Cormar Primo Ultra (1.5 TOG) with Duralay Technics 6 (0.66 TOG) gives a combined 1.16 in-situ TOG. Whether that passes the 2.5 TOG underfloor heating limit and what to do.
Updated 05 September 2026.
Cormar Primo Ultra and Duralay Technics 6: combined TOG for underfloor heating
The combined TOG for Cormar Primo Ultra over Duralay Technics 6, 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 Ultra (1.5 TOG) |
|---|---|
| Underlay | Duralay Technics 6 (0.66 TOG) |
| Published sum | 2.16 TOG |
| UHMA in-situ correction | minus 1 TOG |
| Combined in-situ TOG | 1.16 TOG |
| Standard UFH limit | 2.5 TOG |
| Heat pump target | under 1.5 TOG |
Cormar Primo Ultra is rated 1.5 TOG and Duralay Technics 6 is rated 0.66 TOG. Laid together the combination is what the underfloor heating has to warm through.
The published TOG figures add to 2.16. The UHMA rule subtracts 1 TOG because tests showed real in-situ resistance runs about a TOG below the paper sum, giving 1.16 TOG. That clears both the standard limit and the tighter heat-pump target.
Questions and answers
Cormar Primo Ultra and Duralay Technics 6: combined TOG for underfloor heating?
Combined in-situ TOG is 1.16, under the 2.5 TOG limit, so Cormar Primo Ultra with Duralay Technics 6 is suitable for a standard underfloor heating system. It is also under 1.5 TOG, so it suits a low-temperature heat pump run.