Infrared Underfloor Heating Is Cold in a New-Build Property. What Causes It?

In a new-build house, a common cause of a cold floor with infrared underfloor heating is concrete that has not yet dried out: the heating works properly, but the moisture evaporating from the warming concrete draws off heat, so the surface of the floor covering cannot warm through. The phenomenon is temporary - as the concrete dries, the floor gets warmer week by week.

The heating works, yet the floor is cold

Recently more and more clients have put their heating into operation, and in a lightweight-frame house we met the same problem: no matter what temperature they set the room to on the thermostat, the parquet, that is, the floor covering, did not warm up. We investigated the case. The order of the work was this:

1. we installed the heating film;
2. then came the concreting;
3. after about 2-3 weeks the contractor laid the floor covering;
4. the lightweight-frame walls were raised, the client moved in and started the heating.

The system drew the necessary current, and on a follow-up check we also verified that the films had not failed. The floor nevertheless stayed cold.

The cause: the concrete has not dried out yet

By measurement we found that the moisture content of the concrete was still high. As the heating warms the concrete, the water left in it begins to evaporate, and evaporation draws heat from its surroundings. Because of this, the heating cannot yet warm through the surface of the floor.

As the concrete dries week by week, the temperature of the floor keeps rising. In an extreme case, however, complete drying out of the concrete can take as long as an entire heating season - this is worth reckoning with if floor covering and moving in follow the concreting quickly. When it is advisable to install the heating is covered in our article on the timing of installation.

How can you check it?

The moisture content is easy to check. The phenomenon can be followed most clearly where the wall and the floor meet: this is where it is worth measuring. If the concrete is dry and the floor is still cold, the limit value of the thermostat's floor sensor may also be the cause - we show how to set it in this video article of ours.

You can find more information about the layer build-up of electric underfloor heating on our topic page, and about the thermal insulation under the concrete in our article on underfloor heating insulation.