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Question

I would like to build a skillion roof using single beams (not trusses) it would be clad with corrugated iron. What size/grade timber would I need to span a 4 metre length? The shed's width will be 6 metres.
Woodsolutions Answer +

We don't generally provide design data for specific projects because of the possibility of not fully understanding all details of the proposed structure. Our preference is to refer inquirers to the span tables and design software available on our website here: https://www.woodsolutions.com.au/articles/span-tables-and-software. Since yours is a simple structure we can tell you that MGP10 grade pine could span 4.0 m, spaced at 1200 mm centres, supporting a corrugated iron roof (no ceiling) in a size of 140 x 45 in a non-cyclonic area, wind classification N1/N2. The roofing material could weigh up to 10kg/m2, which would cover common steel roofing materials. Other combinations of materials can be assessed using the design tools referred to above.

Skillion roof

Answered on 15-01-2021
Please note that our answer is based on the best advice available at the time. If the National Construction Code, Australian Standards or local requirements have been subsequently amended, our answer may no longer be correct in all details. For more information, please read our disclaimer.

Question

Skillion shed end wall 4m high other end 2.4m high rafters at 600crs N3 wind rating metal roof. What size studs?
Woodsolutions Answer +

As well as the details provided, a designer would need to know the span of the rafters. That's what determines the load on the stud walls that support the rafters. It's called the Roof Load Width. In the case of a skillion roof the Roof Load Width is half the span of the rafters + eaves overhang, since each wall carries half the weight of the roof. We have software that will help you to work out the size of the studs. It can be downloaded from our website here: https://www.woodsolutions.com.au/articles/span-tables-and-software. Alternatively, your timber supplier may be able to advise on the required stud size.

Skillion roof

Answered on 17-12-2020
Please note that our answer is based on the best advice available at the time. If the National Construction Code, Australian Standards or local requirements have been subsequently amended, our answer may no longer be correct in all details. For more information, please read our disclaimer.

Question

I have a client who is concerned with the structural integrity of the cypress pine posts (100mm x 100mm) we have installed recently as part of a pergola replacement. Linear surface cracking has started to occur and my past knowledge is that this is common. Everyone I have sought advice from has agreed this is a common issue but does not affect the structural integrity of the post itself. I have also spoken to several suppliers that agree however I cannot seem to find any data sheets on the species that would confirm this and ease my client's concerns.

Could you please advise if there are any documents that you know of that may assist with my issue to avoid further dispute with my client and possibly having to replace the posts which I know is not required.

Kind Regards,

Michael Straman.
Woodsolutions Answer +

We assume the posts haven't developed splits right through, from one side to the other - that could be serious. However, surface cracks, or 'checks', are common in cypress pine as it dries and are insignificant with regard to strength. There are many entries on the net describing the effect of surface checks in cypress. Some authorities recommend painting cypress as soon as possible, since a paint coating slows down the drying rate and thus inhibits the formation of checks, more info here: https://outlast.com.au/assets/pdfs/durable-timbers/Cypress%20Pine.pdf. For best results inclusion of heart centre, or pith, should be avoided since cracks develop that track back to the pith. On the information provided we feel your client need not be too concerned. 

Cypress pine

Answered on 15-12-2020
Please note that our answer is based on the best advice available at the time. If the National Construction Code, Australian Standards or local requirements have been subsequently amended, our answer may no longer be correct in all details. For more information, please read our disclaimer.

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