Compared with many floor coverings a padded carpet floor covering typically has increased insulating properties, potentially reducing the efficiency of an in floor heating system. It's important to be aware of the associated R-values of different types of carpets and pads, so that your radiant system can be designed with efficiency and comfort in mind.
Here is a brief comparison of several common types of carpet and pad, and their approximate R-values. All R-values listed are approximate and will vary depending on manufacturer.
Synthetic carpets have similar R-values and can be determined by the thickness of the carpet.
| Synthetic Carpet R-values: | |
| Carpet Thickness: | R-value: |
| ⅛" | R-0.6 |
| ¼" | R-1.0 |
| ½" | R-1.4 |
| ¾" | R-1.8 |
| 1" | R-2.2 |
| Carpet pad/cushion R-values: (*R-values of carpet pad can vary depending on material) | |
| Pad Thickness: | R-value: |
| Prime Urethane carpet pad R-values 2.2 lb/ft³: | |
| ¼" | R-1.08 |
| ⅜" | R-1.62 |
| ½" | R-2.15 |
| Bonded Urethane carpet pad R-values 4.8 lb/ft³: | |
| ¼" | R-1.05 |
| ⅜" | R-1.57 |
| ½" | R-2.09 |
| Jute/Hair/Fiber carpet pad R-values 6-8 lb/ft³: | |
| ¼" | R-0.97 |
| ⅜" | R-1.46 |
| ½" | R-1.94 |
| Waffle Rubber carpet pad R-values 25 lb/ft³: | |
| ¼" | R-0.97 |
| ⅜" | R-1.46 |
| ½" | R-1.94 |
| Slab Foam Rubber carpet pad R-values 33 lb/ft³: | |
| ¼" | R-0.31 |
| ⅜" | R-0.47 |
| ½" | R-0.62 |
It is recommended to use the lowest possible R-value recommended for your application to maintain optimum efficiency and comfort. Add carpet and pad R-values together to get the total R-value of the floor covering.