Cormar Primo Ultra TOG value and underfloor heating
The published Cormar TOG value for Cormar Primo Ultra and the underlay budget it leaves over a heated floor.
Leaves 1 TOG of the combined budget for the carpet on top before the 2.5 TOG limit is reached.
| Range | Cormar Primo Ultra |
|---|---|
| Construction | polypropylene twist |
| TOG rating | 1.5 TOG |
| Max underlay TOG for UFH | 2 TOG |
Cormar Primo Ultra is a polypropylene twist with a published TOG value of 1.5. The deepest Primo twist at 1.5 TOG, where underlay choice decides the combined-TOG result.
Using the UHMA rule, in-situ resistance is carpet plus underlay minus 1. To keep Cormar Primo Ultra under the 2.5 TOG limit the underlay must be no more than 2 TOG.
TOG measures thermal resistance, so a low number means heat passes through easily. For a floor covering over underfloor heating that is what you want. A comfort underlay chosen for warmth underfoot does the opposite job and is the usual reason a heated floor underperforms after a carpet goes down.
Sources: Cormar Carpets published carpet TOG values · UHMA guidance on underfloor heating with carpet and underlay (combined-TOG rule)