Cormar Primo Tweeds (1.2 TOG) with Tredaire Treadmore (1.03 TOG) gives a combined 1.23 in-situ TOG. Whether that passes the 2.5 TOG underfloor heating limit and what to do.

Updated 05 September 2026.

Combined TOG result

Cormar Primo Tweeds and Tredaire Treadmore: combined TOG for underfloor heating

The combined TOG for Cormar Primo Tweeds over Tredaire Treadmore, worked against the UHMA underfloor heating rule.

1.52.5
1.23TOG in situ
Pass · limit 2.5
Published TOG stack (carpet + underlay)
carpet 1.2
underlay 1.03
limit

Combined against the UHMA 2.5 TOG underfloor-heating limit. Under 1.5 also suits a low-temperature heat pump.

Carpet TOGUnderlay TOGPassMarginalFail
Combined in-situ TOG is 1.23, under the 2.5 TOG limit, so Cormar Primo Tweeds with Tredaire Treadmore is suitable for a standard underfloor heating system. It is also under 1.5 TOG, so it suits a low-temperature heat pump run.
The combined-TOG calculation
CarpetCormar Primo Tweeds (1.2 TOG)
UnderlayTredaire Treadmore (1.03 TOG)
Published sum2.23 TOG
UHMA in-situ correctionminus 1 TOG
Combined in-situ TOG1.23 TOG
Standard UFH limit2.5 TOG
Heat pump targetunder 1.5 TOG

Cormar Primo Tweeds is rated 1.2 TOG and Tredaire Treadmore is rated 1.03 TOG. Laid together the combination is what the underfloor heating has to warm through.

The published TOG figures add to 2.23. The UHMA rule subtracts 1 TOG because tests showed real in-situ resistance runs about a TOG below the paper sum, giving 1.23 TOG. That clears both the standard limit and the tighter heat-pump target.

Related checks
Cormar Primo Tweeds TOG value1.2 TOGTredaire Treadmore TOG rating1.03 TOGCormar Pimlico with Tredaire Treadmore1.03 TOG, passCormar Primo Textures Ribbed with Tredaire Treadmore1.03 TOG, passCormar Primo Textures Weave with Tredaire Treadmore0.93 TOG, passCormar Apollo Plus with Tredaire Treadmore1.13 TOG, pass

Questions and answers

Cormar Primo Tweeds and Tredaire Treadmore: combined TOG for underfloor heating?

Combined in-situ TOG is 1.23, under the 2.5 TOG limit, so Cormar Primo Tweeds with Tredaire Treadmore is suitable for a standard underfloor heating system. It is also under 1.5 TOG, so it suits a low-temperature heat pump run.