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Robbens Systems® | German quality with British expertise | since 1993

Profi-joist - fit from below | Underfloor heating for floor joists | Ideal for retro-fit

Between joist install from below spreader plate system

Ideal for a bonded joist and floor deck system. Easy installation from below.

Suitable for both solid and engineered floor joists.


Spreader plates 1 metre in length hold 2 pipe runs. Available in 150mm width. Multiple plates can be installed depending on joist spacings.


Spreader plates are installed from below using adhesive, screws and staples. Gaps are left at the ends to allow pipes to bend through 180°.

Where open web joists are installed, the fiow is connected to the manifold first. A double pipe is pulled to the furthest point, and then the inner pipe is pulled between the joist runs.

Complete this from the furthest point back to the last run, then cut the pipe back at the manifold.

Where solid joists are used, notch the bottom of the joist to allow the pipe to return. Cover with galvanised steel plate to prevent screws or nail damage.


• Carpets -over chipboard deck(> 2 togg)      • Timber-over chipboard deck      • Laminate -over chipboard deck      • Tiles- over plywood deck

Heat-source supply temperature: 50-60°C. In some situations this system can be designed for use with a heat pump. Ask for details.

Pipe Centres: 150mm only. Wider joist spacings can accommodate 2 plates between joist.

Click to download the pdf datasheet

This system includes the following items:

  • Underfloor heating manifold - pre-assembled
  • Aluminium pipe clips - 1000mm
  • Pipe clips
  • Thermostats for each room
  • System control box
  • CAD pipework drawing
  • Electrical wiring guide - first fix
  • Electrical wiring guide - second fix
  • Installation manual
  • Telephone and email support