Underfloor Heating: Timber vs Concrete Floors

You don’t need any special materials to get underfloor heating to work well. A little bit of building physics is in order here.

Heavy, dense objects like stone, brick and concrete are not good insulators but they do have the capacity to hold onto heat for a long time. This is a phenomenon known as thermal mass. In contrast, lighter building materials like wood have much less thermal mass, but do insulate reasonably well. At the other end of the spectrum, materials like mineral wool and expanded polystyrene have virtually no thermal mass (they are very lightweight) but are extremely good heat insulators. These are the crucial factors in deciding how your underfloor heating should work.

What most people look for is to have very good insulation levels under the pipework (so the heat doesn’t escape downwards), and high thermal mass materials like concrete above the pipework. The idea being that the concrete heats up slowly and then gently releases the heat into the room.

If you place timber over your underfloor heating, less heat escapes (because it is a reasonably good insulator), so you may need to run the system a little hotter. However, because the timber floor has less thermal mass, it heats up and cools down quicker than concrete. In fact, it behaves more like a conventional radiator system.

Concrete or screed floors aren’t better or worse than timber ones; they just respond a little differently.

Further reading:

• Find more advice on heating systems
• Find more advice on heating and plumbing in the How-to Guides section
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