Can I fit underfloor heating to my project?
Underfloor heating systems can be installed in any type of building and with most types of floor structure. Here’s a guide to the key points you need to know before starting different types of project.
New builds and complete renovations
You’ll need to plan your use of underfloor heating from the very start of the project. Your first task is to decide what heat source you’re going to use as this can affect the way your underfloor heating is installed and used.
For example, if you’re planning to use a heat pump, you’ll need to install additional pipework and choose a floor type with good thermal mass. This will make sure your heat pump works as efficiently as possible.
You’d also be better off choosing suspended floors in block and beam rather than timber. Block and beam has several advantages over timber, including excellent sound suppression, improved fire prevention and good thermal mass. It also makes the underfloor heating installation process easier.
If you’d rather use an oil or gas condensing boiler, you can use any floor type. The pipes can also be spaced a little further apart, which will keep the installation cost down.
The building itself can be made from conventional brick or stone, timber frame, structurally insulated panels (SIPS) or architectural glass and steel. You just need to make sure you follow the latest regulations on insulation levels and airtightness.
The process is similar to the above, although you might not need such a high level of insulation.
Underfloor heating is an ideal choice if you need to remove and replace the ground floors to tackle damp or structural defects. However, you can still install underfloor heating if the ground floor is structurally sound and is the suspended timber type.
First, you need to lift the floor boards to expose the timber joists. Then, insulate the floor between the joists and fit the pipework to the insulation. (See the Floor Types page for full details.)
If the joists are strong enough to take a thin layer of screed, this should also be applied. A layer 20 to 25mm deep will increase the weight of the floor joists by around 25kg/m2. This adds thermal mass to the floor, improving the performance of your underfloor heating.
Lifting the floor boards is also an ideal opportunity to treat the joists with preserving agents to give long term protection. Or, you could use an overlay system such a Variotherm.
For suspended first floors that are structurally sound, your choices are quite limited. You either have to take up the floor boards, take down the ceiling or fit an overlay system with a new floor over the top.
An overlay system is more expensive and adds around 25 to 50mm of extra height to the existing floor. Because of this, you may prefer to install radiators instead of underfloor heating.
If your property has a solid ground floor, then removing the radiators and fitting underfloor heating won’t be straightforward. You’ll need to install the pipework into a new overlay floor, which requires a minimum space of 18mm plus the floor board.
As noted above, using an overlay increases floor height by around 25 to 50mm. If you’re not happy with this, you’ll have to remove the existing floor to give you enough space to fit the new insulation, pipework and finished floor.
The normal depth of existing screed is typically 50mm and this can be very easy to break up and remove.
If your floor already has insulation below the floor slab (oversite concrete), we can supply a special 4mm thick insulation foil to lay over the exposed slab. This foil reflects the heat from the pipes up into the new screed. A reinforced screed of 46mm deep can then be applied to bring the floor back to the same level.
The method for retrofitting underfloor heating to rooms with suspended timber floors is the same as described in Partial Renovations above. For other options, please see our Floor Types page or contact us for advice.
Retrofit projects tend to be complicated, so we’ve put together some Frequently Asked Questions and Answers to help you decide how to proceed – click here to read them.