TogCheck
Underlay TOG rating

Cormar Primo Naturals TOG value and underfloor heating

The published Cormar TOG value for Cormar Primo Naturals and the underlay budget it leaves over a heated floor.

1.52.5
1.4TOG
Suitable for UFH

Leaves 1.1 TOG of the combined budget for the carpet on top before the 2.5 TOG limit is reached.

PassMarginalFail
Published value
RangeCormar Primo Naturals
Constructionpolypropylene twist
TOG rating1.4 TOG
Max underlay TOG for UFH2.1 TOG

Cormar Primo Naturals is a polypropylene twist with a published TOG value of 1.4. A natural-look Primo twist rated 1.4 TOG, in range for underfloor heating with the right underlay.

Using the UHMA rule, in-situ resistance is carpet plus underlay minus 1. To keep Cormar Primo Naturals under the 2.5 TOG limit the underlay must be no more than 2.1 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.

Underlay pairings
Cormar Primo Naturals with Duralay Technics 5combined 0.96 TOGCormar Primo Naturals with Duralay Heatflow for Carpetcombined 1.15 TOGCormar Primo Naturals with Tredaire King (Duralay King)combined 1.2 TOGCormar Primo Naturals with Duralay Durafit 650combined 1.5 TOGCormar Primo Naturals with Tredaire Softwalkcombined 3.09 TOGCormar Primo Naturals with Tredaire Dreamwalkcombined 3.53 TOG

Sources: Cormar Carpets published carpet TOG values · UHMA guidance on underfloor heating with carpet and underlay (combined-TOG rule)