Internal and external wood fibre insulation boards - UdiUnger-Diffutherm

UdiUnger-Diffutherm wood fibre insulation boards are:-

  • used in UdiFRONT and UdiIN systems
  • the original, renderable, wood fibre insulation board, used for over 25 years.
  • breathable, eco friendly and used on flat solid walls and timber frames.
  • the best and most simple way to insulate low energy homes, including Passivhaus homes.
  • used inside and outside as part of our solid wall insulation systems.
  • great for keeping you warm in the winter and cool in the summer. 

    Where is it used?
    • The UdiUnger-Diffutherm wood fibre boards can be used for internal (UdiIN) and external (UdiFRONT) solid wall insulation on brick or stone (a levelling coat of render may be required if the surface is uneven) or for direct fixing to timber frames to form a breathable and durable insulation system.

    How is it used?

    • In short, by screwing it to the wall and rendering it. Simple.
    • For the full installation guide please download here  or read through the quick summary below.
    • Wall surfaces need to be flat and smooth so there aren’t any voids behind the boards once installed.
    • UdiUnger-Diffutherm boards should not be installed less than 300mm above the ground level with either plinth insulation coming up to this point or a plinth rail to start the system off.
    • Ideally there should be no horizontal or vertical joints within 300mm of the corners of any openings. If there are then the UdiSPECIAL ADHESIVE must be used to glue the joints.
    • UdiUnger-Diffutherm boards should be laid in horizontal rows, with the tongues pointing upward and firmly fixed with UdiASSEMBLY fixings using an average of 9 fixings per m2.
    • We’ve got junction detail drawings and loads more info here.

    How much will you need?

    • Each UdiUnger-Diffutherm Insulation board is 1300 x 790mm which is just over 1m2 but allow of 5-10% for waste depending on the complexity of the walls.
    • If you need to go greater than 120mm try using a layer of UdiTHERM underneath the boards.
    • UdiUnger-Diffutherm boards can be purchased by the board or by the pallet (12.5% discount on single sheet price).
    Thickness Board size Pallet size
    60mm 1300 x 790mm, 1.027m2 17 boards, 17.5m2
    80mm 1300 x 790mm, 1.027m2 13 boards, 13.4m2
    100mm 1300 x 790mm, 1.027m2 10 boards, 10.3m2
    120mmm 1300 x 790mm, 1.027m2  8 boards, 8.2m2


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