Does anyone have any definitive documentation in relation to building tolerances? I have a SIP building that is +20mm on overall length (10m elevation) and +15mm on width (6m elevation).

I am being told that NHBC, TRADA, UKTFRA and some un-named british standard all allow a 20mm variation from floor to floor.

It seems a little fishy to me as 20mm variation is in all likelyhood +/-10mm. Therefore the building is outside these tolerances anyway. I can't track down a document from any of these organisations that pertains to the tolerances. Apart from one from the NHBC which gives the tolerance as +/-8mm.

We have a problem as the oversize building has closed up our residual cavity. We can get round it by backing off our stonework but as you can imagine it's a considerable amount of work.

Thanks for the reply and I guess from your name you must be an expert!

+/-5mm was the specified tolerance for foundation and so it follows this would be the same tolerance for the setting out of the sole plate. It would seem a little strange for someone to build the entire basement level of a building to such a close tolerance only to allow someone to cut a piece of wood for a sole-plate to a lesser accuracy!

I'd agree that in general building terms but surely for a factory cut panel system one would expect to better that?

I was told +/-10mm by the supplier initially and that would have been achieved but for some of the panels not being pulled up tight on the over-length elevation. If an open joint in that elevation had been pulled up the building would have been within +/-10mm and we would have been OK.

Timber, any information you have on the tolerances would be extremely helpful especially if you happen to have a copy of the relevant document. We've nailed down the sole plate tolerance to the manufacturers construction manual but the upper storey are a little looser (no puns intended!)

The company uses a BBA certificated system but the manufacturer doesn't seem to want to get involved. (or at least haven't shown an interest yet) We've been down various routes of looking at getting a TRADA inspection etc but it's expensive and we don't really want to put our lives on hold for months or years while lengthy court battles are fought out.

We're taking a pragmatic view that if we can get the rest of the building up and work around/repair various other deficiencies we can start to put the whole sorry episode behind us. You are correct about the splash course but in this case the SIP building sits on a conventional basement level that was built up with both skins first. We knew the required tolerances were tight and so managed to build to less than the required +/-5mm on length/width and with +/-2mm on height. (we even leveled a 10m run of steel work supporting the rear of the building to less than 1mm!) It's so depressing to think what has happened after six months of agonising over getting it right.

I truly wish that we were in the position of thanking the supplier for a job well done and handing over a cheque for the final payment. It would certainly be lot easier and less time consuming than what we're having to go through at the moment.

You could try BS 5606, BS 6750 and ISO 1803

Regards

Barney

Ben

The problem is not with the panels, it is the soleplate. My fitters will typically spend two days accurately fixing the plates, checking levels, diaganalls, etc. Once the Soleplate is fixed this forms the template for the job. The end panel on an elevation will often need to be trimmed to fit, today we had to trim a panel by 6mm on a site in Huddersfield.

Tom

trimming should be minimal when we have a long run of panels, the manufactured panels (OSB) have a tollerance and can be say 1222mm wide instead of 1220mm, hence we can get a little creep.

but the soleplate is key and good site practice