Is it safe to go with ceramic tiles for underfloor heating?

We are planning to purchase a four-bed house in Dublin. We placed a booking deposit also. We are considering going for underfloor heating (UFH) with electric mats, at least for the ground floor. The UFH company which gave us the quote suggested that ceramic tile or stone would be much better for flooring to get maximum heat out of UFH.

We also looked at various sites on the internet and they seem to corroborate what the UFH company told us. We are happy to go with ceramic tiles.

In the meantime, I saw a recent Property Clinic query here where someone asked a question about cracks in the floor in their house. In your reply it was suggested that it could be due to UFH and it cited research done by the Building Research Establishment on this. This has again raised doubts in our minds.

I would like to know if it is safe to go with ceramic tiles when adopting UFH (with electric heating mats), or are floor cracks a possibility?

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Thank you for the question and I wish you all the best with your proposed purchase. You have clearly completed some good research in relation to the underfloor heating system (UFH) and I would trust the advice provided by the supplier-manufacture installing the system.

When the Building Research Establishment (BRE) completed its testing on underfloor heating systems, they focused only on warm-water UFH which was more commonly used at that time.

The first time I encountered an electrical UFH system was part of a house refurbishment in 2006 when it was installed in a small bathroom. The concern I had then is the same concern now: the installation. The key for the system to operate correctly is ensuring that no damage occurs to the heat pads or cabling (these are the same concerns with warm-water underfloor heating pipes).

I am assuming you are buying a new home as you have placed a booking deposit. The BRE paper was primarily completed relating to new build construction or where a new concrete floor slab was laid. The findings at that time “identified that the cracking normally occurred within weeks of the heating system being operated post installation and cracking was almost always caused by movement of the screed at a pre-existing crack or, in some instances, a ‘day’ joint in the screed”.

The fault was that of the concrete slab construction and not the UFH system installation. I would recommend you speak to the main contractor on site and obtain confirmation on the type of concrete floor they are installing, including “build-up” and pass this information to your UFH supplier or sub-contractor. Subject to sale completion, you might need to allow additional time for drying of the concrete slab before installation of the new UFH system.

Where an UFH system is installed, the use of tile finish is recommended, as it provides the best heat-up times in comparison with other construction materials (vinyl, wood, carpet). However, the drop-off rate or cooling time from the max temperature is also quicker. Ultimately when a UFH system is turned on, this will be for a prolonged period so the cooling time should not largely feature as part of the decision process. The type of tiling you use internally will mainly be dictated by budget and style so natural, ceramic or porcelain tiling are all good options.

Finally, you want to ensure that any system you source from a supplier is installed by their approved installer, and that you are provided with a product and workmanship warranty. – Andrew Ramsey

Andrew Ramsey is a chartered building and project management surveyor and member of the Society of Chartered Surveyors Ireland scsi.ie