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I'm interested in using a timber building system to construct a 3 story motel with underground carpark, where should I start?

Woodsolutions Answer +

The residential part of a motel is a Class 3 building according to the BCA. Our Technical Design Guide #02 deals with timber-framed Class 3 buildings and can be downloaded here: https://www.woodsolutions.com.au/publications


Can you please advise me on what F5 pine timber, spaced 600mm, would span 4.8m, n1 wind area, with a colourbond roof and cementboard ceiling for a pergola?
Also, can you please advise me on what size beam, to span 3.6m supporting the above mentioned roof?

Woodsolutions Answer +

We assume you are using F5 seasoned (kiln-dried) timber, ie. dried after treatment if it’s preservative treated. Referring to the span tables in the Supplements to Australian Standard 1684, rafters of 190 x 45 will span 4.8m at 600mm centres. A verandah beam of 240 x 45 can span 3.6m supporting the rafters. We assume the cement board ceiling is 4.5mm HardieFlex or similar.


Can you advise if F Grade or GL is preferred for strucurral floor joists in commercial building. Live Load requirment is 4KPa.

Woodsolutions Answer +

F-grade and GL grade are equally suitable as long as the F-grade material is kiln-dried. Some F-grade timber is marketed unseasoned, but glue laminated timber is always fully seasoned. Of course both must be the correct size for a 4kPa load. If the floor joists are exposed on the underside the glue laminated material may have a more highly finished appearance, but otherwise either one will do the job.

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