There are two main types of under floor heating (UFH).
Firstly, the “wet” system. This is basically a long, winding pipe that runs under the floor, connected to the boiler. Much like a radiator, it pumps hot water round and back to the boiler on a loop via a “manifold” or control centre.
Within the wet system installation, there are 3 ways they can be installed:
When constructing an extension, usually a concrete “slab” is laid as part of the foundation. The pipe work insulation boards are then laid on the concrete with the under floor heating pipe work then clipped to it. A cement based “screed” then encases the pipe work. This is quite a cost effective way of installing and it offers the most effective heat output, especially when tiling above. The heat distribution is even and when the heating is turned off, it continues to radiate heat for some time afterwards. The advantages of this system are as follows: They are relatively cost effective to run. Being just, in essence, a large radiator connected to the boiler, they just attach on to an existing heating system. The heat they give off is indirect, that is, they radiate heat evenly and heat a room very effectively.
If the sub floor structure is timber, I.e. a typical suspended floor of joists and floor boards, then insulation is laid between the joists and aluminium trays are hung on the joists, The pipe work is then clipped to the trays. This can be cheaper to install than having to remove the timber floor and pour concrete and screed.
To retro fit a wet UFH system, it is often possible to fit a slim line system over the existing floor. This is usually disced by the height of the door threshold, I.e. if the front door is sitting a minimum of 20mm above the floor level, there will be enough height to install the system over the existing floor boards. This system, although not quite as effective as laying in a screed is much cheaper to install.
The other UFH system commonly used is an electric matting. It is cheap and easy to install during a build, but can be expensive to run. One would normally find then installed in a bathroom as part of a bathroom refurbishment. As with the wet system, the electric matting would sit on an insulated board with the tiles laid on top. In simple terms, it is a long electric cable laid under the tiles connected to a thermostatic control box on the wall.
Providing it is only used as a comfort feature, I.e. to warm chilly tiles, and not as a primary heating source, then it is a cost effective way of adding a bit of luxury.
Within this project, we installed the wet and electric systems, with the ground floor being wet and the electric matting in the bathrooms on the first floor.
The rest of the first floor was heated with traditional radiators.
A wall mounted programmable thermostat allows one to program in the usual on/off schedules.
In this instance, the clients chose a wet room shower for the bathroom. This means, instead of a shower tray, the whole floor was tiled with just a screen to separate the wet area. The obvious advantage is two fold. The floor is uniform throughout the room, with no step into the shower.
With his shower set up, it is totally important to structurally stabilise the sub floor. The slightest movement will cause the grouting or even the tiles to crack. This will allow water to escape an untold long term damage if not spotted (usually evident in water staining in the ceiling below).
Our process to stabilise the floor is as follows:
We remove all existing floor coverings and floor boards. We then investigate the floor joists for any wood worm, water ingress or any other damage. All though rare, this is the only time you can sensibly address any damage to the timbers. Most bathroom fitters (which are generally plumbers and don’t know about building!) don’t even lift the floorboards so never discover any problems. We then fit additional structural “noggins” in between the joists. 18mm structural plywood (WBP) is laid on top. Then a layer of “Ditramatting” which is a stabilising layer is applied. You then have a stable base on which to lay tiles! It’s a lot of work, but essential to ensure we never have to return to fix loose or cracked tiles.
The walls also need to be stable but often this just requires a little more plastering. The layer of plaster most people recognise is the top layer, finishing plaster, commonly known as “skim coat” when removing old tiles, they can often pull off this plaster and the base layer or “bonding coat”.
If this happens, we can easily reapply the bonding, or hard wall, which also allows us to flatten the walls for tiling. In very old houses, we sometimes find loose “lathe & plaster” walls which sometimes need a bit of improvement similar to that of the sub floor work we do.
When choosing tiles adhesive and grouts, it is essential to choose the right material to match the tile, I.e. ceramic materials for ceramic tiles, porcelain for porcelain. We would always use a flexible, waterproof, rapid set adhesive for the floor and a ready mix for the walls.
For grouting, same rules apply; flexible & water proof. It’s worth spending the extra for high quality such as BAL or Mapei as they often have mould resistance as well. We advise choosing the darkest colours to suit the tiles as the lighter the grout, the more you may have to clean it over time. Btw, neat bleach is a good cleaning product for dirty grout!
Underfloor heating systems—both wet and electric—offer practical, comfortable, and modern alternatives to traditional heating. Wet systems are ideal for new builds or major renovations, offering excellent heat distribution and long-term efficiency. Electric matting, while better suited for smaller spaces like bathrooms, adds warmth and comfort when used correctly.
Successful installations depend not just on the system type, but also on correct preparation. Ensuring subfloors and walls are structurally sound, using high-quality adhesives and grouts, and following professional installation methods are essential steps. Wet room setups especially require careful attention to prevent future water damage and tile failure.
Whether enhancing comfort or improving energy use, underfloor heating and wet rooms can be reliable, long-lasting upgrades when done properly. Investing in proper preparation and expert advice makes all the difference.
42 Hurst Rd, Molesey,
East Molesey KT8 9AG,
United Kingdom
Phone: +447947040890