I've never got the hang of when timber is going to be the size you ask
for and when it will be smaller, due to the method of sizing the
unfinished product. And it seems to vary around the UK. This never
Now, I have on my plans, sizes like 75mm x 225mm joists to fit into
matching joist hangers, and all the fittings should be tight. I will
order the timber from a proper merchants, since some is graded C24
etc, and must not warp.
So if I order 75mm wide joist hangers will the inside measurement be
exactly that ?
Assuming it is, I need timber that is exactly 75mm wide. However, a
lot of timber is regularized and rounded on the corners, and is
probably smaller than the size you ask for.
What should I ask for to a) not look like an arse (no comments ...),
and b) get the finished sizes I need ?
In the Midlands.
Basically sawn wood should be the size quoted. Planed wood starts out as
sawn and varies slightly according to how much is needed to be planed off
to get it smooth.
So constructional timber should be to the dimensions quoted.
*Seen it all, done it all, can't remember most of it*
Dave Plowman email@example.com London SW
Nope, *standard* timber sizes don't vary that much around the country.
If you can find any 'natural' timber guaranteed *NOT* to warp, let the group
know - BTW, that's why you use herring bone or solid strutting between the
joists to try and stop them moving too much.
No necessarily - if the fit of the joist is too loose for your liking,
simply stick a packing piece on side or the other before fixing the said
BTW, why are you using 75mm (3") thick joists? The standard is usually 50mm
(2") - unless you are trimming around an opening such as a stair well.
If you joists and exact size - then simply ask for 'dimension sawn' timber -
and you will get what you want.
True I know. But for biggish beams like purlins etc, a bad warp could
be enough to
damage an aircrete wall as it dries, I would have thought.
Most warps happen around knots in the wood in my experience, so C24
timber should warp less, since it has less knots in it.
What a load of cobblers - if the joists are that wet, then don't put them in
until they dry out to a moisture content of around 18% - and if they are
*that* wet, tell the timber merchant to stick 'em where the sun never shines
and go and pick your own.
I would have thought.
Another load of cobblers - certainly in my years of experience (many( -
timber will warp, twist, bend and shrink regardless of the amount of knots -
but knots will weaken timber, that's why the number of them will affect the
stress gradings that are used.
Have you seen B&Q timber ? I've got several lengths of 4x2 that are
they get to a knot near the edge, where-upon they diverge at a strange
They were straight-ish when I got them, have been sat outside but
sheltered for 6 months.
I built a partition wall out of them and didn't plasterboard for a few
weeks and the
partition was twisted a fair bit and I had to bend the plasterboard.
If your experience with timber is always reasonable stuff from timber
well there you have it. But B&Q stuff is bad. I don't use it any
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.