D&RW
Design Partnership
Limited

We have considerable experience in the field of sheathed panel timber frame design, both the open panel form where no insulation or membranes are installed in the factory and the closed panel form where such items are installed before the panels are dispatched to site for erection.  We have developed a dedicated, flexible design program which allows us to provide frame calculations and details at very competitive rates whilst cutting the response time to a minimum.  The basic per square metre design cost covers the wind stability assessment, suspended floor design, panel and stud centre design as well as details of all door and window lintels.  Where the introduction of steel elements is unavoidable, for long span splitter beams for instance, the design and detailing is carried out as an additional cost based on drawing time at suitably reduced rates.  In many cases the design and detailing costs of a single beam would be absorbed into the basic design cost, with only more extensive and intricate steel elements attracting a charge by prior agreement.

We prefer to establish a dialogue with timber frame manufacturers in order that we are able to tailor our designs to the manufacturer’s plant capabilities and purchasing regime.  There are many variables dictated by the manufacturer’s plant and labour force, such as the type of floor preferred.  Floors may usually be dispatched as cassettes or as individual elements, for instance.  The type of joists used is also an important consideration.  As well as solid timbers there is now a range of options available in the form of metal web joists and engineered timber I-joists, with the form of items such as trimmers and rim boards being dependant on the joisting used.

There is also a range of options of sheathing type and thickness, with the choice of material affecting the performance of the frames under racking loads.  Similarly, nail spacing and diameter affect the racking capability, but the economic choices may be constrained by the capacity and flexibility of the nailing bridge or nail gun equipment available.  By establishing an effective liaison we seek to provide a design that suits the manufacturer’s established methods, rather than presenting a solution that gives rise to avoidable increases in production costs or plant down time.

In a competitive market, the functions of estimating and tendering for the production of frames are of vital importance.  We offer an estimating assistance service to assess frames with a view to identifying costly elements such as Glulam or steel beams and posts.  A rough size guide is given, with an estimate of the quantity of material required.  Thus the estimating team can be made aware of the need to include for the price of buying in Glulam and fabricated steel at the outset and factor these items into the overall costings.  The time spent on this guide is kept to a minimum, since the manufacturer’s estimating costs are not directly recoverable, but form part of the overhead costs.  In many cases, two or three hours work at agreed rates will suffice to avoid the unintended omission of these expensive elements from the pricing schedule.

Timber Frame Design