Installing Water Underfloor Heating between joists

We have 3 different solutions for installing water underfloor heating pipes in between joisted/suspended floors

Pipe spacing to be 200mm apart or less. This means you need to select a conservatory style kit or a multiple room kit – standard room kits are designed with the pipe spacing at 250mm centers which would mean you would not have enough pipe in the kit.

  • Spreader plate system

    Spreader plate system

    • Aluminum spreader plates are fixed to the joists using screws or nails, the plates have 16mm preformed groves in them set at 200mm centers to accommodate ProWarm™ European Standard Pex-Al-HDPE pipes.
    • A standard installation for this system assuming the joists are deep enough would be to fix batons to the sides of the joists (about 70mm from the top of the joist) then a 50mm foiled faced insulation like celotex/kingspan is cut and placed onto the batons, the pipe work is then clipped directly into the spreader plates.
  • In Joist Foil Boards

    In Joist foil boards

    • These unique boards combined the idea of both the spreader plate and insulation in one system, the 50mm thick XPS insulation panel has the grooves pre formed in them at 200mm centers, the whole board is then covered with an aluminum foil designed to dissipate the heat evenly over the floor above.
    • A standard installation for this system assuming the joists are deep enough would be to fix batons to the sides of the joists (about 70mm from the top of the joist) then place the boards on top of the batons, the pipes can then be clipped directly into the grooves.
  • Dry biscuit mix/screed system

    Dry biscuit mix/screed system

    • Assuming your joists have been approved structurally to take the extra weight increase then this system is best suited for use with air source heat pumps as the dry screed mix acts like a large radiator, storing the heat longer than any other joisted system.
    • A standard installation for this system assuming the joists are deep enough would be to fix batons to the sides of the joists (about 70mm from the top of the joist) then a 50mm foiled faced insulation like celotex/kingspan is cut and placed onto the batons, the pipe work is then clipped direct to the insulation and the screed can be installed on top, level with the joists.
    • We do recommend installing a thin polythene membrane on top once the screed has dried to stop any moisture build up affecting the surface above.

What kit is best for you?

Once you have decided what type of floor construction you have and the installation process needed, find out which different heating kit is best suitable for your project.