I will be fitting a clear plastic corrugated roof, 3" profile and 1.3mm thick between two parallel walls, 1300mm apart. The roof will have a length of 3050mm.

I will be using two pieces of roofing, overlapping.

I intend to afix two 3 metre 50mmx50mm battens on each wall, both at the same height, but both dipping down at one end. I then will fix cross-members at each end.

Question 1: I obviously need to fix intermediate cross members - what would a good spacing be? 600mm?

Question 2: How many fixings will be needed? How far apart should the screws be? Is there any particular order to fix them in?

I don't need advice about eaves fillers or flashing, I have all that in hand.

Thanks.

Thanks for that Dan, I did actually come across that useful site before I posted in researching it, and whilst it did give some useful information, it did not answer those two questions as far as I can tell.

Could the same instructions be used if installing metal corrugated sheets. Our garage has an asbestos roof which leaks, although when sealing round the window frame my son used the same sealant on the roof and 98% of it has stopped leaking when we have heavy rain or prolonged rain. I am looking at possibly moving or renting out the property and if the new owner/tenants have a small car ie Fiesta, Smart car or at least Fiesta size, they would be able to use the garage for the purpose it was meant for. Otherwise it is a glorified shed, which is what we use it for.

Chris

PS My son doesn't know it but he is going to be doing the work. Shhhh......

Thanks Dan, that was really useful.

You'd need to use a crawl board - say a stout scaffolding plank or a sheet of 12mm min thickness ply

Gloucester, what are those metal brackets called that you are using to join the purlins to the side supports please?

Or is it a joist hanger upside down?

Yes, thanks, I was aware of joist hangers - they are supposed to be used the other way up I think so the joist (or purlin in this case) rests in the cradle. Still, seems to work fine in your case