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Bitumen-free sarking boards for walls and roofs


MultiPlex boards are 22mm thick tongue and grooved rigid insulation boards. They can be used externally in place of a breather membrane - not only do they protect the building envelope from wind and rain but they also provide an additional layer of insulation which prevents cold-bridging across the timbers. In addition, a factory applied hydrophobic coating enables them to be used as a temporary wall/roof covering for up to one month.

MultiPlex boards are fully biodegradable.

Composition & Manufacture

  • Manufactured from renewable resources
  • Manufactured from by-products
  • Bitumen-free
  • CO2 zero-rated
  • Timber fuelled embodied energy
  • Actively recycled

Installation & Disposal

  • No known health risks for workforce or installers
  • Easily cut to shape with handsaw
  • Durable / Low maintenance
  • Reusable / Recyclable
  • Compostable


  • Wind and rainproof from 20 degree pitch upwards
  • Acts as temporary roof covering (max. 4 weeks)
  • Eliminates thermal cold bridging through timbers
  • Vapour permeable (SD -Value = 0.11 m)
  • Enhances thermal performance in Winter
  • Enhances thermal performance in Summer
  • Good acoustic performance
  • Hygroscopic (absorbs & releases moisture)
  • Vermin and fungus resistant
  • Electrically neutral
  • Non-radioactive
  • Free from toxins and allergens
  • Dimensionally stable (low thermal movement)
  • Helps regulate indoor climate
  • Low toxic fumes if burn


• Insulating breather membrane for roofs and walls
• Insulating internal lining board (can be plastered)

Part of this web page will not print - please use the product pdf linked on this page


Suitable for 20º roof pitches and above.
Suitable for rafter / support centres up to 850mm.

Racking strength
MultiPlex boards do not provide racking strength. Racking strength, if required, can be achieved with metal strappings or by using a suitable internal lining board. Please consult your structural engineer.


MultiPlex boards must be protected from rain and rising damp at all times prior to installation.
Protect edges of boards from being damaged.

Cut boards using a fine-toothed circular saw with guide and integral dust extractor.


External applications
Install boards with writing facing outwards and with rising tongue. Fully engage board joints (tongue and groove). Butt joints should be primed and taped. Boards are generally fixed with clout nails at 330mm centres or less. It is recommended that boards are fixed by nailing through the counter batten, thereby avoiding any risk of nail or screw heads penetrating the watertight layer.

Associated products
• pro clima BUDAX Tapes (taping of joints)


Raw materials spruce / pine chippings
Hydrating agent natural tree resin
Fire protecting agent none
Hydrophobic coating tree resin / wax emulsion

Dimensions and packaging

Board thickness 22 mm
Board size 2500 x 750mm
Coverage per board 1.81 m²
Weight per board 10.7 kg
Boards per pallet 45
Coverage per pallet 81.4 m²
Weight per pallet 500 kg

Technical data

Density, ρ 260 kg/m³
Thermal conductivity, λR 0.050 W/m.K
Thermal resistance, R 0.44 / 0.72 m².K/W
Diffusion resistance, µ 5
Compressive strength, σm: ≥ 150 kN/m²
Bending strength, σ ≥ 1.5 N/mm²
Water absorption ≤ 1.0 kg/m²
Fire rating Class B2


• DIN 68775-1- WF-P-Wh-050-H10-B2
• Certified by Institute of German Master Roofers

Date publishedTitleFile sizeDocument type
MultiPlex-Top - bitumen-free sarking boards for walls and roofs
261 KB Product sheet
Typical design details (roof sarking)
38 KB Technical data sheet
Sitework (roof sarking)
141 KB Technical data sheet
Design and installation notes (internal lining)
21 KB Technical data sheet

To order this product, or to request pricing / quotations, please do one of the following:

- call us at 020-7232-1181
- fax us at 020-7023-3789
- email us at
- use our online quotation request form.

Our hours of business are Monday to Friday, 10.00 to 18.00.

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