One slight problem I had with the planks for my bed frame project: The three 2.4m planks (145mm x 19mm) appeared dead flat in the plastic pack, but within hours of opening the pack I noticed very slight cupping on two planks and a slight twist on the other (like a cheese straw, but not as pronounced!) The cupping and twisting are minimal and barely noticeable in the finished bed fram unless one knows how to squint along the long side from a low vantage point.
But how might one minimise this effect? Are planks stored flat in the open, as two other stock yards practise, better?
Buy only timber that's been planed to size *after* the humidity in it has settled to that of your room. If it come in sealed plastic wrapping, it will almost inevitably warp, IME.
Or go to a decent woodyard, not one of the sheds. Banana shaped timber is endemic from the DIY sheds, which is why I don't use them unless the result is (a) hidden and (b) strength is not important.
Yep, buy from a timber merchant. Shrink wrapping prevents the wood from losing moisture so that it stays flat until you open it. Proper merchants store their prepared timber upright and under cover, so that it's outdoors but doesn't get rained on.
If its wood on view, you can plane or sand it flat, but leave it for many months to stabilise first. If its just slat material, no need to do anything.
I priced up a project recently using standard lengths and standard sheets from a shed and the cost came to around £200. I took my cutting list to my local timber yard where the materials, cut to size, were then delivered to my door for £86.
But it is transported from places like Scandinavia on the decks of ships, stored open to the elements on dockside timber yards and I've never seen it covered on the lorries delivering it. Perhaps the problem is actually storing it in heated DIY sheds rather than storing it outside or in an unheated facility.
The woodyards I buy from tend to import it as sawn roughly to size, then they leave it for a while under cover and finish it on site. They may even be kiln drying some of it before working on it.
This happens a greater or lesser degree depending on species of wood, how it was stored and importantly how it was cut from log (quarter sawn etc)
When I built my place I wanted to make sure all my custom moulded skirting's, fascias etc. stayed true .... I had anti cupping grooves machined into the back on them. Longitudinal slots about 4mm wide x 5mm deep .... 3 slots along all lengths.
Two of the timber merchants I know both store their timber flat, in stacks. But, yes, outdoors under cover (although in one case the "shed" is open to the elements from the front).
I thought of doing exactly that, though only one slot. But in the end I decided the degree of cupping was so minor as to not worry about it. Later this week I'll put some pics on my web site so you can see whether you can see it!
The norm is that the mill routinely dries the material to 17% moisture content (at which point it's no longer vulnerable to the dreaded blue stain) with a huge travelling hair dryer, and that's how it normally arrives in UK. Storage under cover with good air circulation can reduce this to 15% in summer, but that's about as dry as it gets outdoors.
Drying it further (secondary kilning) is reckoned to be a bad idea, so most furniture manufacturers will specify a moisture content direct from the mill and have it shipped in a container. That way it's taken from green to, say, 10% in one kilning, but it's a long and expensive process when the material is tight grained. An Ikea bed slat can be dried much faster because it's fast grown and open grained
The basic problem is that softwood used indoors will end up at
They are held flat by the pack and by being bound to others with packing strip. Also the pack keeps in the humidity. When they dry out the bend and cup. B&Q is the worst. Wood from timber yards is better, but in my experience is getting worse. I had a load of 2x4 that was all slightly cupped - got away with it on stud walling though. I forget to fix one stud at the bottom against the wall and it twisted out of plane with the wall.
In the old days, timber was naturally dried and seasoned, then cut and planed when it had finished moving. Also timber now is cut from fast grown narrow trunks so the grain has a log smaller radius and more prone to twisting / cupping.
If you can use the timber quickly and it is held in place it will not twist, but I'm not sure if when unbound after drying it would "spring" into its desired twisted shape.
When I put in some timber joists recently (75mm x 225mm) a couple were slightly twisted along the length. Before I put the ceiling up you could see a wonky engineering brick underneath ... a the wonky end of the joist !
A lot of builders are using TJI / engineered joists since they do not suffer from this.
General building timber is in general getting poorer quality in my experience.
I missed the original response to my terse statement but I stand by it.
The sheds mainly buy rubbish, pre-shaped and packed. It is of uncertain humidity content and quality.
Builder merchants who store do so in generally similar conditions to te expected wood uss (PAR and rough sawn inside, pressure treated outside, but under a bit of rain protection) , and get plane stock from places who also store properly and shape internal timber under approximately similar conditions to the expected use.
Also the smaller the wood dimensions the more likely it is to be s**te. They are made from all the odd grained bits of lager baulks - but conversely, they can easily be bent into shape, and, over a period, will conform to the shape so bent to.
In all cases its down to wood selection, and the selection of the outlet who conditions the wood best to your requirements, or if you are a perfectionist, doing your own plane-finishing from specially seasoned wood..
Wood is a very poor structural component stability wise. The art of joinery and carpentry is to minimise the impact on the final articles. It is however cheap. Which is why we bother with it at all. If its very cheap, it is seldom worth having at all. Shed wood is really cheap - they expect at least 3:1 markup, whereas a BM and a trade account is no more than 50%..
If I buy timber at a DIY outlet, I unpack and leave to dry out for as long as possible before use (at least a week, preferably a month). I generally get two usable planks out of a pack of five. I use the others where it doesn't matter (e.g. floorboards where they can be screwed down flat, or where a short piece is required), although I currently have a surpless of them.
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