Energy Waste

How Underfloor Heating Insulation Can Avoid Energy Waste

Correctly insulating the floor can make a world of difference when using underfloor heating insulation. Without the proper insulation, the heating system may heat the room more slowly because the heat will also be going out the bottom of the heat source, whether it is electric cables or water pipes, thus wasting energy and money.

Cold air also infiltrates the floor so that the floor itself requires more energy to heat up. Even in a home without underfloor heating, insulation is a good idea to help keep cold air from coming up through the floor.


Underfloor heating is reasonably easy to install, however you will need an electrician to wire it. Most of these systems come with wiring diagrams.

Insulation can come in many forms. It can be rigid foam that typically comes in 4’ by 8’ or 2’ by 8’ sheets. Often the 4’ by 8’ sheets come perforated to fit nicely into a floor joist cavity.

Polystyrene foam boards are also an excellent choice because of its excellent insulation characteristics as it is waterproof, it has high resistance to compression, it’s rot resistant, and it is very lightweight and easy to work with. It can be cut easily with a sharp knife. Sometimes it comes in a cement type form like a tile backer board in a 3’ by 5’ sheet.

Screed, a substance similar to concrete, can also be used like insulation. Screed will help to level out any imperfections in the floor as well as help to transmit heat evenly throughout the floor. If no access is available to the area under the subfloor, then a thermal primer can be used so that the floor height is not raised, thus reducing the height of the room. Thermal primer provides a reflective surface to reflect heat back up into the floor.

Underfloor Heating Supplies


Room Size

Calculation How Much Underfloor Heating Insulation Is Needed

Figuring out how much insulation will be needed is an easy mathematical process. Measure the length and width of the room and multiply the two figures. For instance, if the room is 12 feet long by 10 feet wide multiply 12 feet (length) by 10 feet (width) to get a room area of 120 square feet. A 4’ by 8’ insulation board is 32 square feet. Divide 120 (square feet of room area) by 32 (area of 4’ by 8’ insulation board) to get 3.75 rounded up to 4 which is the number of sheets of insulation that will be needed to insulate the room.

For rooms that are irregular shapes try to divide the room into rectangular sections to figure the area of the room then add the sections together to get the total room area. Always over figure a little bit to allow for waste, usually about 10 percent will work. Sometimes just rounding up on sheet totals will do the trick.

underfloor heating insulation

Efficient Heat

Follow manufacturer specifications when attaching insulation and make sure to follow any and all safety precautions. Underfloor heating insulation can usually be attached using nails, screws or glue. Certain types of tape may be recommended at the joints to attain maximum insulation efficiency.  


Underfloor heating is an excellent way to heat the home. It is energy efficient and quiet and more importantly, it can save money as long as you use underfloor heating insulation. 

Read The Facts


There are numerous suppliers of water underfloor heating systems and we are not here to recommend one supplier over another. Instead we want to give you the independant facts to help you make up your own mind based on your own individual needs. Read more...