Application  >  Timber external walls

Application - External Timber  Walls 

Natural Wood Fibre rigid Sheathing & Sarking boards are installed over the external timber frame of a building providing an air tight, water repellent, insulating, noise proofing layer.


  • Water resistant (acts as a sarking board)
  • Excellent insulating properties
  • Boards can be exposed to the elements for up to two months
  • Excellent soundproofing qualities
  • Vapour open. Allows trapped moisture in the wall fabric to escape
  • Reduces thermal bridging in the building elements
  • Tongue & Groove on all 4 sides preventing unwanted air drafts
  • Prevents dust blowing into the building envelope
  • Provides structural strength to the building element
  • Versatile - boards can be covered with a cladding material or with a natural based render
  • Good fire resistant qualities (see video)
  • Easy to cut & install 
Perfect for timber structures

The rigid insulation boards and high density gives them structural properties.  Install them as you would any other sheathing material such as Plywood or OSB.


Can be cladded over

The insulating boards are fixed to the frame with timber battens & screws. Cladding such as timber, fibre cement or metal are then fixed to the battens.

The battens provide an ventilation gap between the insulating board and the back of the cladding; allowing trapped moisture in the building fabric to evaporate.

Water repellent boards

The wood fibre insulation boards are hydrophobic meaning they repel water.  They act as second water protection layer behind your cladding.


They can be left unfinished for several months allowing you to get your house secured from the elements.

Suitable for a render finish

The sheathing and sarking board is very versatile. It can be finished with a natural lime render or earthen render.

Fixing methods  
Boards fixed over a timber frame 

The sheathing boards can be temporarily secured to the timber frame with typical wood screws. Battens can then be fixed over the boards and secured into place with timber screws.

wall drawing.png
For rendered boards

If you are planning to render the board; they can be secured to your timber frame using large head stainless steel staples or specialized screws with a plastic washer. 

Need more technical information ?

You can download the a guide to the Installation Guides to the Rigid insulating  Sheathing & Sarking boards;  as well as the board's Product Data Sheet our Downloads section.