NBT Diffutherm - Timber Frame

Diffutherm Benefits

NBT Diffutherm System is for timber frame buildings externally finished with render. Diffutherm systems use NBT Pavatex woodfibre boards over the outside of the frame in a continuous layer.

The racking board is fitted on the inside of the structure, acting also as both the airtightness and the vapour control layer, in a fully breathable construction.

Externally a Baumit mineral based, thin render system is applied directly to the Diffutherm boards.

 Internally we recommend a service void between racking board and plasterboard for effective airtightness control and easy service alterations.

System Benefits
  • Excellent thermal performance, with very low thermal bridging (y values)
  • Excellent air tightness
  • Excellent acoustic insulation
  • Excellent overheating control
  • Robust and easy system to install
  • Fully breathing construction
  • Full design and site support from NBT
  • All systems components from NBT
  • Tried and tested system, fully certified
  • Full system support


System Application

Pavatex Diffutherm Timber Frame Wall Buildup

NBT Timber Frame Diffutherm System can be used with any conventional timber frame design, provided that the racking board is fixed on the inside of the frame rather than the outside. The same limitations apply as to all timber frame applications. The Diffutherm system has a good fire rating and is suitable in many situations requiring fire resistance. Contact NBT for further details.

The significantly lower cold bridging through studs and y-values(psi) means that the Diffutherm system outperforms traditional timber frame systems. The insulation layer is continual, including into reveals and returns.

Click here to download a printable PDF of this system

Environmental Performance
  • Carbon positive (locks up more than is used) and non toxic
  • Woodfibre Boards are over 95% waste
  • FSC Certified source
  • Zero Landfill - recyclable, compostable or used for thermal energy production

Diffutherm Performance

Pavatex Pavaframe U-Values and Performance

Code for Sustainable Homes

Diffutherm offers a simple and cost effective route into Levels 3 and 4 of the Code for Sustainable Homes. Below are some simple performance and product specifications to achieve CSH Levels 3 and 4 - do please contact us if you are aiming higher than this for up-to date advice.

System Components
  • Insulation boards: Interlocking, waterproof Isolair boards (22, 35, 60mm), Pavatherm Plus+ boards (60, 80, 100mm).
  • Tapes and Glues: Pavatape for exposed edges, valleys, hips, ridges, service penetrations etc.
  • Also special glues for board edges on pitches between 10°and 20°. On pitches over 20° board edges are not glued.
  • Fixings: A range of helical and screw fixings for different boards and roofing materials
  • Infill insulation: NBT provide natural insulation materials such as hemp, sheepswool and through sub-contractors cellulose
  • Plaster boards and paints: NBT can provide clay boards, plasters and trade environmental paints for ceilings

For more information, download the following. Please right click and'save as'. If you have any problems downloading any information, please contact us for assistance:

NBT Diffutherm Basic Information Sheet

NBT Timber Frame Full Technical Manual for Designers and Installers.

NBT Diffutherm System Fire Performance

Pavatex Systems LANTAC Certificate

Pavatex ISO 14001 Certificate

Diffutherm on Timber Frame BBA Certificate