weird artifacts - shadow/aa/not sure

Hi i’m doing a vr piece and have a problem with a couple of assets producing very pronounced artifact’s that are visually very jarring (see video)
I’m using a forward path, and lighting is static. I’ve turned off dynamic shadows on the objects in question and have tried different AA types but the problem persists. Interestingly it only affects the trusses in the roof and the tall cupboard things. I’ve even re-modelled the cupboards to check it wasn’t geometry, but the problem persists.

http://www.a-vr.co.uk/downloads/shadow.mp4

I will keep digging but hoped someone here might recognise the effect and have a solution?

Thanks in advance,

Felix

I had set my near clipping plane very low (0.001), to allow for near viewing at smaller scales - reverting to a more reasonable figure (0.1) removed the issue.