Architects should have designs on timber frame

The doubts are overcome
By Mike Cruickshank

Every so often, it becomes clear that a technology’s time has come. The doubts are overcome, the arguments are won and the benefits become obvious and undeniable. At this point, the technology becomes an industry standard.

This is very much the stage timber frame construction is at. Despite rearguard actions by proponents of traditional brick and block construction methods, timber frame now ticks the boxes in so many areas – from sustainability and carbon footprint to labour costs – that the real surprise is that anyone still builds by other means.

Why should developers and the industry persist in building on sites which are wholly at the mercy of the weather and indifferently-skilled labour, when the opportunity exists to fabricate off-site in the controlled environment of a modern, high-tech factory?

But as timber-frame becomes increasingly dominant, is a different mindset now required from architects? After all, timber frame construction not only maximizes flexibility and ease of construction but takes full advantage of potential standardization to reduce costs.

Architects have not exactly been widely encouraged by developers to introduce bold new innovations in commercial house construction of late, but the combination of a new political will to increase house building and the limitless possibilities of timber frame should put them back into the driving seat when it comes to influencing the built environment.

ON-LINE DEBATE

Computer-based design in an architect’s office can integrate seamlessly with the engineering and manufacturing systems and highly automated plant in a modern timber frame factory. The architect can engage in online discussions with the manufacturer as the project progresses and design out potential problems before the job reaches the site.

The system takes weather out of the equation and superstructures can be erected quickly, efficiently and accurately – reducing sub-contractor costs and taking the guesswork out of pricing.

Getting the manufacturer involved in the design process at an early stage makes sense at many levels, not least on costs. But the architect can contribute substantially to cost savings and efficiency by accepting minor adjustments which need not compromise architectural integrity.

The most fundamental area in which cost-effective considerations should be taken into account is the floor plan. Ideally, to reduce labour and wastage from cutting standard size plasterboard and flooring sheets – and to suit standard stud and truss centres – buildings should be designed using either a 90mm or a 140mm stud depth on a 600mm “grid”, measured from the inside face of timber frame to inside face of timber frame on the external walls.

Ceiling heights should be designed to standard plasterboard dimensions. Although non-standard panel heights can be priced to the nearest standard height up, there will still be wastage and on-site labour costs for cutting.

In the design phase of the ground floor, it is vital to consider the spans of the upper floor joists. If joist spans are designed near to their limit, it increases deflection whilst avoiding excessive spans solves a number of traditional problems, including ensuring that load-bearing partitions are positioned correctly.

DESIGNERS IN DIALOGUE

Designers, in a dialogue with manufacturers, can also benefit by standardising external door lintel heights and window dimensions. For instance, a lintel height of 2.1m from finished floor level will accommodate most external door sets and increase choice. Non-standard internal doors should be avoided.

Bespoke windows are attractive from a design point of view, but are expensive and can lead to delivery delay. It may be possible to achieve an architecturally similar effect by combining the widths of standard modules.

Using the “grid” plan referred to above will also reduce the number of trusses needed for “room in the roof” designs using dormer windows, Velux windows and stairs. Stairs themselves can be finalized at the design stage to make them fully compliant with new building control requirements.

The variety of standard skirtings and facings and the materials from which they are made – is now so extensive that there is no real need for specifying non-standard items. Once again, all they will do is increase costs and delivery times.

The technological advantages of timber frame construction are an opportunity for architects to make an impact on the urban environment as never before. If designers work in tandem with reputable manufacturers, the benefits can be reaped not only in cost and time, but in the quality of people’s lives.

Images show example of Scotframe projects

[Mike Cruickshank is Sales Director at Scotframe Timber Engineering. The company operates across the UK and Ireland from its bases in Inverurie near Aberdeen, Cumbernauld near Glasgow, and Hillsborough in Northern Ireland and employs over 200 people. Current turnover is in excess of £35m.]

More information: www.scotframe.co.uk