¦ SpaceStud can use home-grown small section C16 timber.
¦ Wall depths up to 258mm are possible.
¦ Stewart Milne is using SpaceStud as the structural component in its Sigma II build system.
¦ SpaceStud offers roof truss and flooring manufacturers an additional product area.

The need for ever-lower U-values is pressing the timber frame sector to look to deeper wall sections.

I-joists, with their deep sections, dimensional stability and reduced thermal bridging, have shown one way of achieving this, while a variety of insulation combinations are on the market for standard timber frame.

Another route starting to make inroads is ITW Industry’s SpaceStud – a system successfully used in Scandinavia – which uses two smaller section studs connected by metal clips to create a 258mm-deep wall.

The twin C16-graded flanges are either 38x63mm or 38x89mm, while the metal strip connecting them is either 55m or 80mm deep – creating a stud, ITW says, that is deeper than readily available solid timber to accommodate thicker insulation. Solid timber end blocks feature at each end of the stud.

Only three pairs of metal clips are used to connect the flanges over a 2.4m wall height, which ITW says help reduce thermal bridging compared to rival open-web [timber flange and metal web] products which are also now making the change from floor applications to walls.

Improved racking performance

ITW claims SpaceStud delivers a 20% better racking performance than standard 38x140mm timber frame panels. The solution is being billed as a cost-effective solution to achieve high levels of the Code for Sustainable Homes.

It is also in line with the UK Timber Frame Association’s Fabric First campaign, which highlights the benefits of using timber frame as the core fabric of a building to achieve high Code levels, rather than relying on renewable energy systems.

ITW says the system also creates a route for home-grown timber to access the next generation of timber frame technology.

Home-grown C16 wood sizes can be limited above 140mm but the use of smaller sections in SpaceStud offers an opportunity for the material – in fact, several of the timber frame manufacturers already using SpaceStud are doing so using home-grown timber as part of the mix.

Deeper walls

“SpaceStud is mainly for timber frame companies to be able to create a deeper wall,” said Tim Widdershoven, ITW Industry marketing manager. “But they may not manufacture their own trusses and floors because they have no press, so they buy them in.

“For roof truss and engineered floor fabricators, this is an opportunity to produce more products.”

He said roof truss and open web floor fabricators did not need additional software and the studs could be assembled on standard truss or floor presses at up to 120m/min.

Mr Widdershoven said the principal benefit of SpaceStud was the ability to include thicker insulation and detailing for the use of Rockwool and Kingspan insulation. Solid timber equivalent panels, he added, were a very expensive option, while I-joists were expensive to treat.

He said ITW was optimistic about SpaceStud’s prospects and the company was developing a new press for the product’s manufacture.

Stewart Milne Timber Systems and Ochil Timber Products are timber frame manufacturers currently using the system, but Mr Widdershoven reported many other companies expressing interest. Some are actively quoting on the system, with the intention of outsourcing to existing licensed fabricators (flooring and roof truss fabricators).

Stirlingshire-based Ochil Timber Products is using SpaceStud to achieve target wall U-values of 0.19-0.25W/m²K.

Structural component

Meanwhile SpaceStud is currently the structural component part in Stewart Milne’s Sigma II closed panel building system, which is being used on development sites across the UK. Sigma II is a past winner of the TTJ Award for Achievement in Sustainability.

Stewart Dalgarno, group product development director for the Stewart Milne Group, said the company had done a significant amount of testing with SpaceStud in the Sigma II system, which also comprises a host of other features.

It is using both home-grown and imported timber in the manufacture of the studs.

Sigma II is being used on the second Carbon Challenge site – South Bank, Peterborough, where hundreds of Code Level 6 homes are to be built. The first prototypes are already under construction.

Mr Dalgarno said Stewart Milne was looking at using Sigma II on even larger projects of up to 1,000 homes.

Sigma II will be used for a sustainable building project in West Lothian after Stewart Milne, in conjunction with Malcolm Fraser Architects, won the Whitecross Design Competition. It will involve a first phase of 70-80 homes of a proposed 1,500-unit expansion of the village of Whitecross.

Sigma II is also being used to build the 92-unit Serpentine development in Oxford Road, Aylesbury – a former Territorial Army base – a joint venture between the Homes and Communities Agency and Denne in partnership with Thames Valley Housing.

Stewart Milne, which replaced German company WeberHaus as the timber frame solution provider, will go on site in March.