From £24.57 + VAT per board

Internal and external wood fibre insulation boards – Diffutherm

Diffutherm wood fibre insulation boards are:-

  • used in external insulation and internal insulation systems.
  • the original, renderable, wet-process wood fibre insulation board, used for over 30 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.

Product overview

Where is it used?

The Unger-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 video installation guide please click 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.
  • 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 system adhesive must be used to glue the joints.
  • Diffutherm boards should be laid in horizontal rows, with the tongues pointing upward and firmly fixed with the system fixings using an average of 9/m² externally or 6/m² internally.
  • To see how to use this product on masonry in rendered walling applications see our guide here – How to install on masonry rendered wall insulation
  • To see how to use this product on timber frame in rendered walling applications see our guide here – How to install on timber frame rendered wall insulation

How much will you need?

  • Each Unger-Diffutherm Insulation board is 1290 x 780mm which is 1.0m².
  • Allow of 5-10% for waste depending on the complexity of the walls.
  • If you’re not sure which board you need please contact us.

Frequently asked questions

What is their thermal conductivity?

The Diffutherm boards have a conductivity of 0.046 W/mK and a density of 230kg/m³.

Pricing & shipping

Thickness [mm]Weight [kg/sqm]Board dim. [mm]Number of Boards per palletPallet covers [sqm]Per pallet [kg] single board costboard cost in full pallets
609.61275 x 765, 0.975m²3029.25300£27.30£24.57
8012.81275 x 765, 0.975m²2221.45300£34.57£31.11
100161275 x 765, 0.975m²1817.55300£43.03£38.72
12019.21275 x 765, 0.975m²1514.625300£47.90£43.11

Book your free project consultation

We’d like to hear from you. Call us on 01392 861763 or email us at with any questions or comments.

If you can’t seem to find what you need on our website or you have large quantities of materials to purchase please contact us for a chat and we’ll offer you a more bespoke solution.

We’re normally open from 8.30 am to 5 pm Monday to Thursday, and 8.30 am to 1pm on Friday.