From £19.25 + VAT per board

Universal Wood Fibre Insulation Boards – Pavatex Isolair Multi

Pavatex Isolair Multi universal wood fibre insulation boards are:-

  • dry process wood fibre board suitable for use on roofs, walls and for rendering.
  • suitable for use on masonry and timber frame buildings
  • high density, giving great summer heat shielding, keeping your home cool.
  • quick to form a weather-tight, bat friendly roof covering without using membranes/felt.
  • ideal for use in noisy or urban areas where their acoustic insulation really helps.

Product overview

Where is it used?

  • On top of rafters to prevent thermal bridging and keep noise out, especially useful for loft conversions.
  • Behind any wall cladding on timber frames or masonry.
  • In locations where direct application of plasters or renders is required.
  • Any roofs where bats live. They get tangled in breathable membranes so are a great alternative.

How is it used?

  • When used as a sarking board, the Pavatex Isolair Multi wood fibre insulation boards should be laid on top of the rafters and covered with a breathable membrane before being fixed in place with counter-battens.
  • For roofing applications the first row should start at eaves level and working in rows, work your way up the roof.
  • To reduce waste the overhang from the first row should be trimmed off and used to start the second row and so on.
  • For use behind cladding the same principles apply.  When working on masonry structures, unless the wall is very flat, timber battens should be fixed to the surface first with SteicoFlex flexible wood fibre insulation between the battens. The Pavatex Isolair boards can then be fixed to these battens, avoiding any voids behind.
  • Alternatively, apply a levelling plaster to the surface of the wall, texture with a knotched trowel and fix the boards to the surface whilst still wet.
  • Any cut joints or corners can be taped with Ampacoll Fenax tape to ensure weather-tightness.
  • Boards are not suitable for walking directly on unless supported underneath.
  • For installations where the boards will be left exposed for more than 8 weeks or where metal roofing is to be used, install Ampatop Protecta breathable membrane over, prior to fixing of the counter-battens.
  • To see how to use this product in roofing applications see our guide here – How to install roof insulation
  • 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
  • To see how to use this product on timber frame in clad walling applications see our guide here – How to install on timber frame clad wall insulation

How much will you need?

  • The Pavatex Isolair Multi boards are 1860 x 590mm and cover 1.097m2 per board.
  • They are available from our stock in 40, 52 and 60mm thicknesses.
  • Allow 5-10% wastage depending on the complexity of the roof/facade.

Frequently asked questions

What are their thermal conductivity and compressive strengths?

The Pavatex Isolair Multi boards have a conductivity of 0.041 to 0.044 W/mK, a density of 145 – 200 kg/m³ and a compressive strength of 100 – 200kPa (kN/m²), depending on thickness.

See it in action

Wood fibre sarking boards - Over rafter insulation

Wood fibre sarking boards - Flat roof construction

Pricing & shipping

This product will require two pallet spaces and so shipping is likely to cost between £100 and £200, depending on where you live. Contact Us for a more accurate costing.

Thickness [mm]Weight [kg/board]Board dim. [mm], Area [m²]Number of boards per palletPallet covers [sqm]Pallet weight [kg]Pallet dim. [mm] [LxWxH]single board costboard in full pallets
407.241860 x 590mm, 1.097 m25661.434251900 x 1200 x 1300£19.36£17.43
529.411860 x 590mm, 1.097 m24043.883961900 x 1200 x 1300£24.55£22.10
6010.861860 x 590mm, 1.097 m23639.494101900 x 1200 x 1300£28.78£25.90

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.