Underfloor heating (UFH) floor types.

These are the four main construction types:

Solid Floor
solid floorunderfloor heating

Either concrete slab or block and beam. The floor type looks like this, On top of the ‘slab’ or the block & beam you will need to lay some insulation. This is normally a high density board type such as ‘Kingspan’ TP10 or similar. The pipe system is laid on this and held in place with either a pipe rail or pipe clip. Screed is then laid over to the finished floor level. This floor type has good thermal mass and is considered the best floor type for UFH.

Floor build-up
Block/Beam, Slab or Oversite – Normally 100 – 150mm of concrete
Insulation – Ideally 65 – 100mm of high density board
Screed – Liquid screed = 50mm, Sand/Cement screed = 65 – 75mm
Floor covering – Stone/Tile, Timber, Laminate, Carpet

Note: Allow for the floor covering height when calculating the total floor build-up.

Suspended Timber Floor – No Thermal Mass – Ideal for First Floors
suspended underfloor heating

This fast and simple answer is best suited to well insulated buildings using oil or gas boilers. The water flow temperature is around 40 – 60 C depending on how well the building is insulated.

No need to cut insulation boards between the joists. No need for expensive and time consuming heat diffuser plates. Just roll out this 4mm thick unique foil product, hold it in place with the clips and then fit the pipe! The floor boards are then fitted directly over the foil and clips in the normal way. The pipes warm the still air between the foil and the floor boards and the foil reflects the heat up into the floor.

Benefits - Quick and easy to install with a fast response time.

Note: This floor type cannot be used above any uninsulated area such as a garage. For that situation you must use the next floor type with the correct thickness of ridged insulation board.

Suspended Timber Floor – Good Thermal Mass – Ideal for Heat Pumps
suspended underfloor heating

Thermal mass allows the water flow temperature to be much lower (35 – 45 C) and still give out high energy performance. The depth of the ridged insulation boards would be 60 - 100mm for ground floors (or any floor where the space below is unheated) and 25mm for first floors etc. A space of 20 – 25mm is left between the top of the insulation and the underside of the floor boards for the pipes and the sand/cement filling. This is a just a weak semi-dry mix that has no structural strength. The additional weight on the joists is approximately 25kg/m2. You must design the floor joist to accommodate this extra load.

Note: The sand/cement filling can be omitted when using this floor type with oil or gas boilers. When using a sand/cement filling it must be allowed to fully dry before the floor boards are fitted. Failure to do this will result in moisture from the cement distorting and damaging the floor boards.

Floating Floor
floating underfloor heating

Used when putting underfloor heating onto an existing floor that already has insulation in it or where the space below is heated. This is a special type of system comprising of insulated panel, pipe and heat diffusion plates. The insulated panel is available in different thicknesses for floors that require a higher amount of insulation.

Floor build-up
Existing floor (concrete of timber) in good sound condition
Insulation panel – 25 – 50mm (including pipe)
Heat diffusion plates – Around 1mm thick
Sub-floor – Either timber floor boards or specialist solid floor panels
Floor covering - Stone/Tile, Timber, Laminate, Carpet

There are a number of variations to these main floor types.

For solid floors timber battens can be fixed to the oversite concrete as a fixing for floor boards. This can be useful when the normal drying time for screed floors is too long for the build program. If this is the case then heat diffusion plates would be used in place of screed.

For suspended timber floors in timber framed buildings where the floor ‘deck’ is fitted in with the frame the UFH has to be installed from below. The pipe is fixed to the underside of the deck, either by a clip or a different style of heat diffusion plate. Insulation is then pushed up and fixed in place. This can be the same foil Radiant use for the standard suspended floor or a rock wool blanket.

If your project requires a variation to the main floor types we will recommend the appropriate solution in our quote.

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