Is structural birch or spruce ply weatherproof and suitable for a garden shed?
I recently constructed a shed from 20mm Brazilian Pine structural ply, sourced from my local "Timber Centre." They are "CE" marked "class 3".
The salesman assured me that it was suitable for exterior use but some panels have warped and de-laminated. All panels were first treated with "Johnstones all purpose wood preserver" and exterior varnish (also Johnstones) prior to construction, in dry conditions.
I have burnt-off the old paint and applied a solvent-based "shed and fence" treatment and no more damage is evident. Some of the panels were OK, but most suffered from a surface fungal growth.
Could these problems be due to poor storage and transportation by the timber merchant?
Shoggy
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 Shoggy, The Brazillian ply should be weatherproof, it is designated WBP which means Weather and Boil Proof (I think). I would be reluctant to use it for external work unless it is properly sealed or protected on the edges where they are most vulnerable. If yours is a recent construction and sheets have delaminated I would definately complain to your supplier this should not happen. See the Manager and explain whats happened (you wont be the first) he may send someone to look or he may just give you a refund. If you dont tell them they will never know. Regards, Malc.
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 Shoggy, WBP, or water and boil proof board is usually a deep reddy brown in colour is extremely stable and very expensive, I have not bought any for a while but I expect the cost to be about £58:00 per sheet. Shuttering ply will stand up to the weather and is quite cheap, this would be the stuff I would use. You obviously do not have weather proof ply. Derek.
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Shoggy/Derek, Brazilian Ply and most shuttering ply is WBP. The £58.00 per sheet is most likely Marine Ply and is made with glue that does not break down in water so can be submerged although you still have to protect the surface areas with e.g. Yacht Varnish. Shoggy, your Brazilian Ply is made with waterproof glue and should not de-laminate, it is recommended for external structures like sheds.. Malc.
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| Edited: 05/08/08 09:44 |
.jpg) I bought some WBP a while ago (I'm pretty sure it was Brazillian) and I payed just over £30 for an 8'x4' sheet of 18mm thickness. Shuttering ply will of course be cheaper but then you're going to be looking at defects, such as dead knots, mainly on one side, so they will probably need filling.
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Exterior glue bonded ply will have a quality number on it, either EN 636, or EN 13986 These are the british styandards for exterior grade ply. derek.
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 Hi Shoggy, You say Brazilian Pine Structural ply, the key here is Pine. This is a good product for structural use but it is normally covered and shielded from the elements, I'm not surprised it has delaminated when used for a shed. I suspect the pine wood has decayed as well. Whatever the grade of ply wood will still rot and dry out if left uncovered, the glue won't but that is of little consequence. I've had hardwood exterior ply rot away completly in 4-5 years when left exposed. In all honesty you get what you pay for exterior pine ply may be good to line a shed but not to clad the xtterior, here feather edge or shiplap are the best and will last 20 years or so with regular maintenance. Ashley
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Thanks for all the replies, very useful.
I was unable to reply sooner because my library blocked access to the getwoodworking site. Lancashire Library's Websense ststem marked it as a gambling site. It's taken over two months to sort out, and I'm not holding my breath.
My shed is resisting the weather, I've burnt-off the black mould and treated the panels with Cuprinol spirit-based shed and fence preserver. I've fitted a proper gutter and downpipe and this has helped keep the rot out.
thanks again
Shoggy
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 I've heard a lot of things said about us woodworkers but gambling is a new one!
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