Electric Underfloor Heating comes in various systems and depending on what you are doing may or may not add to your final floor height.
Where you are pouring a new slab and wish to have an in-slab system as storage heating, the heating cables are tied to the reinforcing mesh and have no impact on the final floor height.
In many cases once a slab has been poured or in a renovation project and where the floor is to be tiled, the tilers insist on doing a sand and cement screed across the floor to ensure it is dead flat and even to tile upon. In this case the floor heating is laid under the screed and either a mat system or loose wire screed system can be used. This does not add to the final floor height other than the fact the screed is already adding to the height. This heating does not require any extra height of screed.
Under tile heating refers to heating that is laid directly beneath the tiles in the tile adhesive. Thermonet under tile heating mats or cables are 3.5mm thick and designed to be used with a 10 or 12mm notched trowel so that the heating effectively disappears in the tile adhesive and does not add to the finished floor height at all. In some cases, the tilers prefer to put a thin 4mm slurry over the top of the heating before tiling. Whilst this is not essential some tilers prefer to do this for extra peace of mind that they cannot damage it whilst tiling and to ensure they can get the tiles absolutely flat especially if using tiling clips. In this scenario it will add 4mm to the final floor height.
With any floor heating system, it is recommended to insulate the substrate to stop heat going down into the substrate and ensuring you get maximum heat in your room and the fastest response time. This can also reduce your running costs by up to 40%. Insulation boards come in 6mm and 10mm thick boards and when installed under the heating will add this height into the final floor height.
When laying carpets, the floor heating is laid between the underlay and the carpet and are a super thin foil which adds no additional height to the floor finish.
When installing a timber floor over floor heating there are various build ups however typically a 5mm rigid insulation board is laid down first then the heating foil and then a vapour or acoustic barrier over this adding a total of 9mm to the total floor height.
In conclusion, typically the floor heating adds minimal height build up to your floor. For help with your particular project contact the Thermogroup team at firstname.lastname@example.org