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Question

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.

Question

 I have some raw western red cedar cladding an indoor sauna. There is a shower (rarely used) immediately next to the sauna with the shower base grouted right up to the cedar. The shower water hits the cedar wall and runs down to the base. There has been some shrinkage of the cedar leaving a small gap against the base where water can disappear down the gap. Can you suggest some kind of sealant that would adhere to both surfaces to fill the gap? I have heard that silicone will not stick to the cedar very well due to the high oil content. 

Woodsolutions Answer +

Western red cedar does contain oils but it is not oily to the touch. Its oil content can only be extracted by distillation or chemical treatment, ie. there is no ‘free’ oil. Cedar does not repel timber finishes, in fact it accepts all finishes well, including water-based products so its oil content is unlikely to repel silicone sealer, or prevent it from adhering. While we don’t anticipate a problem caused by oiliness, it seems some tradies have had problems with sealing cedar, eg. see this blog: https://www.finehomebuilding.com/forum/good-caulk-for-cedar-siding. One user suggests rough fibres can create adhesion problems, so in your case maybe the end-grain of the boards could create difficulties. We always respect the views of timber users, since we are not in a position to test different products, so you might follow the advice on the blog and go for DAP 230 – there seems to be a consensus that it is fairly reliable. Whatever you decide to use, the timber must be completely dry before you apply the sealant.

Question

I have to install an exposed "eaves beam" under a 900mm roof overhang (some protection afforded) in a coastal area (SA). The Engineer has specified 240x45 F17.
I would prefer not to "clad' the beam but leave exposed - although I would be painting it in a suitable white paint.There are several spans; the maximum is 4m. For a continuous span construction i have spans of 6.6m, 7.5m and 9m. The beams are supported on hardwood posts (F17) - I still have to decide on a suitable connection?
I don't like the idea of several short hardwood timber spans joined over the posts, so i considered glulams ands lvl's. Unfortunately my research has left me a little confused. What would you suggest as a suitable exposed, but painted eaves beam?

Woodsolutions Answer +

Glulam is available in F17 grade but, if made from radiata pine, would have to be preservative treated to AS 1604 Part 5 if it is going to be in the weather. Note that AS 1604.5 requires any surfaces exposed after treatment, by cutting to length, notching or machining, to have a wood preservative applied. This is to restore the protective envelope. Alternatively it might be possible to source glulam made from a naturally durable timber. On the other hand if it is possible to extend the eaves sufficiently beyond the eaves beam so that it is protected from rain, durability is not important. Regarding the connection of beams to posts, the most positive method is to use a proprietary connector bracket, eg. one of the Simpson Strongtie stainless steel post caps.

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