Fit From Below Double Heat Spreader Plate

Suitable for use with traditional composite joists, this system offers the ability to fit from below, even if the floor above has already been installed. Perfect for cellars or where upper floor coverings are already in place.


Features & Benefits of using the Fit From Below Double Heat Spreader Plate system:

  • Can be used with both traditional or composite (I beam) joists
  • Ability to fit even if the floor above has already been installed
Material Requirements (Approx.)
Pipe 4.5m/m²
Heat Spreader Plates 2 plates/m²
Fit From Below Double Heat Spreader Plate installation guidance
  • Step 1: Fitting the spreader plates

    Fix the fit from below spreader plates to the underside of the timber decking. The floor joists can then be drilled in accordance with Building Regulations so as to facilitate the passage of the pipes between the joist gaps and to allow the entry and exit of the pipes to and from the room.

  • Step 2: Place pipes into the grooves

    Once the spreader plates have been fixed in place the pipe can be fitted into the grooves in a serpentine pattern. It is recommended that the flow pipe from the manifold be taken to the furthest point of the room when installing the circuit as this ensures that sufficient heat is provided around the perimeters of the room.

  • Step 3: Fitting the insulation

    It is essential that a suitable layer of insulation material is installed directly beneath the panels so as to minimise any downward heat losses. It is recommended that the thermal resistance of this insulated layer should not be less than 0.75 m²K/W as specified in BS EN1264-4.

  • Step 4: Testing

    Once the pipe circuits have been installed and connected to the manifold, the system should be pressure tested to 6 bar for a minimum of 1 hour before the timber floor covering is laid. It is recommended that the system remains under pressure whilst the flooring is laid.

  • Step 5: Finishing

    It is strongly recommended that the timber floor covering is laid immediately after the underfloor heating pipes have been installed and pressure tested to eliminate any risk of damage to the system by other trades.

    Either traditional tongue and groove floorboards or 18mm/22mm chipboard can be fitted directly on top of the spreader plates. These can be fixed directly through the spreader plate down into the joists below. It is important to indicate the position of pipework in areas where the additional fixing of items such as carpet grip rod or door threshold strips may be fitted at a future date. Polypipe does not recommend the application of two layers of timber floor covering as this will severely reduce the heat output of the underfloor heating system. If a manufactured timber floor is to be used then it is recommended that this be of a suitable load bearing quality. (Please request advice from the specialist flooring supplier.)

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