Can You Have Underfloor Heating With Carpet?

There is a certain assumption that underfloor heating solely works with hard floors such as wood, laminate, and tiles.

Many would dismiss carpet, yet it is also a floor covering that works with underfloor heating. All it needs is a few considerations to make sure you can enjoy the comfort of underfloor heating in a carpeted room.

In this guide, we will look at the considerations you need to make, how you install carpet with underfloor heating, and the benefits you can expect.

The Considerations For Carpet And Underfloor Heating

Make sure that you confirm the carpet you will be using strictly because the combined TOG value with the underlay should not exceed 2.5 TOG. Any more and you will not feel the benefit of the underfloor heating.

The TOG rating of the carpet is more important as the underlay should only be around 0.5 to 0.6 TOG if it is designed to be used with underfloor heating.

As a general rule, underfloor heating, such as Wundatherm Premium+ boards will output ~50W/m² when a carpet is used which can be compared to tile which outputs ~100W/m², and wood/laminate flooring at ~70W/m².

You may be tempted by thicker underlays which are said to offer more insulation, yet the underfloor heating needs to radiate heat, so the carpet is significant.

Wool carpet should be worth looking into, though the underfloor heating may take longer to heat the room, the insulating nature of wool will retain the heat.

Also, ensure that your installer knows the rooms which will be carpeted, so those essential heat loss calculations can be made prior to the underfloor heating system being installed.

Those calculations can include how the boards are installed, the layout of the pipework, and the estimated heat loss as the carpet covering will have an impact.

This is especially important for properties that were built prior to 2013 and simply paying for a professional to perform these calculations is advisable to ensure that the underfloor heating works as expected.

If the expected heat losses with carpet are too great then an underfloor heating system can still be installed but laminate and tile should be considered with a loose rug. Heat loss calculations typically account for around -4°c outside and 22°c inside.

In the milder months, rooms can be heated well even with the rug but during the colder months, it may be best to roll up the rug to allow the full heat of the floor to come through.

How Do You Install Carpet With Underfloor Heating

Once you have made the decision to install carpet with underfloor heating, and it is the suitable TOG with the underlay, there are further considerations to be made.

Wundatherm Premium+ boards would be ideal for the underfloor heating though would require using Duo Board or renovation screed as an intermediate layer.

The Duo Board creates a flat surface which is ideal for carpet and underlay to be fitted on top. Further considerations need to be made for carpets that are to be laid with edge grippers.

Fitting Perimeter Strip

The perimeter strip will help reduce heat loss and allow for expansion which is a crucial part of the overall installation. Prior to laying the heating boards, remove any skirting boards or doors as this will require trimming before the final floor finish.

Fit the perimeter edge strip to the outside edges of the area that will be heated by using the sticky tape on the back of a hand staple gun.

For carpets that will be laid with edge grippers, fix an appropriately-sized batten up to the same height as the boards around the perimeter of the room.

Installing The Boards

Lay the boards flush against the batten to allow for fitment of the carpet gripper later. This should mean there is no risk of fixing it through the pipe or panel which can become problematic.

You may need to cut some boards and this can be easily done with a fine-toothed saw or craft knife.

For any floor heating pipes that need to pass through walls, drill the holes before laying the boards then protect and seal the pipe ends with tape.

Your installer should take into consideration that carpet is due to be installed, and the pipe layout drawing should show where the boards and manifold will be positioned.

Take the time to plan out the transitional pipe runs and how the carpet will look once in place. Ensure that the surface is clean and flat before the boards are installed.

Installing The Duo Board

The Duo Board is made from high-density fibreboard and has an exceedingly low thermal resistance which allows heat to transfer quickly for added comfort.

Comprised of two layers, a base board with an adhesive surface then a top board, which are laid in an overlap/brick bond method.

Installed over an underfloor heating system, the Duo Board provides a stable and level base for carpet to be fitted onto.

It should be noted that Duo Board is not suitable to be used in bathrooms, en-suites, or wet rooms as the boards would expand with moisture.

Fitting The Carpet And Underlay

Once the Duo Board has been installed, the surface should be flat and the carpet with underlay can be fitted. Remember that the combined TOG rating should not exceed two TOG.

You can try the ‘double-stick’ system which helps avoid uneven heating pockets and requires the heating to be off for 48 hours before laying and for the same period after. Gradually over a week, it can then be brought up to full working temperature.

The Benefits Of Having Carpet With Underfloor Heating

Of course, a carpet can add to the cosiness of a room, yet there are also hygiene benefits too. The carpet will be warm and soft underfoot, with underfloor heating the room will be heated for an even more inviting, comfortable feel.

A layer of carpet will also absorb dust which will go some way to trap those particles that provoke allergies and asthma.

Unlike a conventional radiator system which tends to circulate dust particles with air, no circulation occurs and there should be less dust as a result.

Final Thoughts

Indeed you can have underfloor heating with carpet, yet there are some considerations to make first to ensure it is effective for your home.

Carpet can be a truly comfortable and warmer choice underfoot than wood or laminate flooring which is common with an underfloor heating system.

However, it has to be the right carpet which means checking the combined TOG rating with the underlay. It does require a little more effort and Duo Board should be installed underneath the carpet to provide a flat surface.