From £5.42 + VAT per board

Internal wall insulation – UdiTHERM NF

UdiTHERM NF boards are:-

  • a T&G wood fibre board for internal wall insulation.
  • designed for the safe and simple insulation of masonry walling.
  • in a small format to enable the boards to follow undulating walls.
  • extremely effective at improving comfort and reducing heat loss.

Product overview

Where is it used?

  • As insulation on the interior of any masonry walls, both solid and cavity.
  • They should only be used above ground as they are not suitable for cellars or basement walls.

How is it used?

  • The surface of the wall should levelled off with the Baumit Viton Fein plaster and left to dry back before attaching the boards.
  • Once the surface of the plaster is ‘green hard’ (not soft enough to push your finger tip into but soft enough to push your finger nail into) the boards can be fixed.
  • Make sure they are in the correct position and then fix with 3 masonry fixings, spaced evenly down the long centre line of the board. Do not over-tighten the fixings as this will make aligning the T&G profile with adjacent boards difficult.
  • Once the boards have been installed, the UdiMULTIGRUND vapour regulating plaster can be applied to the surface. Apply a 4-5mm coat, incorporating the UdiREINFORCEMENT mesh and finish flat.
  • After 4-5 days the surface can be skimmed with a lime or clay skimming plaster.
  • For detailed guidance on installing and direct plastering the boards, please see our installation guide – Internal wall insulation with lime plaster finish
  • For detailed guidance on installing and using a plasterboard finish, please see our installation guide – Internal wall insulation with plasterboard finish

How much will you need?

The UdiTHERM NF boards are 1186 x 366mm and either 40 or 60mm thick, they cover an area of 0.4134 m² per board. Allow at least 5% for wastage.

Frequently asked questions

Are they heavy?

The wood fibre boards themselves have a density of 160kg/m3 and so weigh around 2.8kg each for the 40mm and 4.2kg for the 60mm. They are easily installed without any specialist lifting equipment.

Can the UdiTHERM NF boards be used on timber studs or timber frame?

The boards can be used on a timber frame but only over a carrier board such as 12mm OSB or ply. This is because the boards are not rigid enough for use without extra support.

What is their thermal conductivity?

The thermal conductivity of the UdiTHERM NF boards is 0.038 W/mK, which is equivalent to the SteicoFlex flexible wood fibre insulation.

See it in action

Internal wall insulation with lime plastered finish

Internal wall insulation with plasterboard finish

Pricing & shipping

This product will require one pallet space and so shipping is likely to cost between £50 and £100, depending on where you live. Contact Us for a more accurate costing.

Thickness [mm]Board Sizes [mm]Board coverage [m2]Number of Boards per palletPallet covers [sqm]Single board costBoard cost as a full pallet
401186 x 3660.4348436.46£6.48£5.83
601186 x 3660.4345724.74£9.52£8.57

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.