Why do people say you need 600mm centres but sheet materials come in 2440mm X 1220mm sizes? So after first one the joint will not hit a support due to a he extra 20mm on each width?
Its easy enough to trim a sheet to size, best to have the sheet slightly over sized, if undersized will cause a much bigger problem. I'm guessing here that sheets used to be imperial 8'x4' and 2440 x 1220 is (a) the metric equivalent and (b) erring on the oversize a bit for the reasons stated. Just my hunch.
Depends on how wide the support beam is...but agreed cumulative error will get you in the end. If its T&G..do the edges always have to sit on the beams ? Rs
Putting ply on to a shed roof, if centres are 600 mm, after a few sheets the join will be missing the trusses? Don't see trimming 20mm of each sheet width be any saving? Time trimming and wasted materials? Surely better to get joists to fit board?
Perhaps it's because it will allow you to fit to older structures at 24" and 16" centres and newer ones at 600mm centres. You can cut it off, but you can' stick it back on PhilSo
dependant on what it is you can work round it if you are building say a shed or garden room your first consideration would be plank sizes as these are metric
The building industry is still confused regarding which unit of measurement it would prefer. Unfortunately it still uses both metric and imperial, so if you've bought 8ft sheets either space your studs at 16 or 24inch centres.
You have to learn to covert between imperial and metric and know what sizes sheets and timber come in, after a while it becomes natural. With timber there is also the difference between the sawn size which is in imperial and the finished size which is usually in metric. Plumbing is really random.
The largest market for sheet timber materials is the US market. That's why manufacturers offer sheet timber materials in imperial sizes.
It gives you some trimming material. A product mostly used in full sheets say plasterboard is best 2400. If a product is to be cut then imagine you need say 400mm strips. This will allow for minimum waste(3 mm kerf=6×3=18mm)
Most don't these days. American imperial is the same as ours( apart from gallons). I struggle with feet and inches tbh. It takes to long to add it all up! In fact adding up inch fractions is a real pia. And something that gets trickier as your out of practice. Mm are a nice measure as there just right to see with the naked eye. Any smaller and I'm struggling!
Is the actual weight different though? Or is it we use stones. Old anvils are marked in stone which confuses muricans noend. 3.78l in murican gal 4.54 l UK gal. I brought a square in Japan on holiday marked in traditional Japanese measure. Guess what it was a bit over an inch! Very confusing.