• BOPAS+


  • Design
  • Manufacture
  • Construction


  • The Donaldson Timber Systems Ltd Sigma II System

With offsite construction currently in use for one in five new homes across the UK, industry stakeholders know it to be low-risk, durable and exceptional value. Across our UK factories we have capacity to manufacture up to 10,000 units per annum and the ability to flex our manpower upwards to accommodate larger projects and shorter lead times. We have three manufacturing facilities, one at Witney, near Oxford and the second and third at Westhill and Falkirk in Scotland. These enable us to meet the requirements of the UK market with ease and justify our market-leading position. Our timber engineering and construction knowledge provides greater flexibility for new-build home designers and our closed panel Sigma® II build solution offers excellent energy, sound and air-tightness performance.

All our timber frame solutions are covered by ISO-9001 quality certification, covering all areas of the business including design and manufacture. We are also the first timber frame manufacturer in the UK to receive the prestigious BOPAS+ accreditation.


The Donaldson Timber Systems Ltd Sigma II System

Durability Assessment – 60 Years

Sigma II System is a closed panel timber platform frame structure with the external wall panels pre-fabricated from a framing of C Studs with  structural OSB sheathing fixed to internal and external faces and with the resulting void fully filled with proprietary bead polystyrene insulation. The wall panels are factory finished with reflective foil type breather membrane. On site a service void is achieved by fixing timber battens and plasterboard to the inside face of the panel. External claddings, windows, doors and roofs are site specific.

Durability Assessment – 60 Years

Limits on scope

– Maximum 4 storeys

– Base plate of wall minimum 150mm above external ground level

– Traditional pitched or flat roof with eaves and verge projection

– Minimum 19mm drained cavity behind cladding

Donaldson Timber Systems has constructed the following site(s):

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