May sound like an odd question but what is on the roof? A neighbour has composite slates I'm not sure what they are made of. In the direct sun they make a loud pooping noise as the expand and contract. She says they have done this for years since the house was re-roofed.
Just a thought.
The moisture difference between the wet mortar on the lower surface and the drier air on the upper surface is the cause. Not much option but to pull them off and start again.
To plane out the cupping would be better done with the window boards out and you may find that they will end up so thin...
C grading is only for softwood. Structural hardwoods upto a certain size are graded as D grades then above that go to THA THB grades. C and D grades are mechanically graded which is why you can get graded timber that is worse than useless, computer says yes! THA and THB are visual only grades...
What type of conservatory? Is it a joinery made kiln dried hardwood number or a green oak frame? Pictures would help. It does sound like a dogs dinner though.
Nails. The theory is that screws are cast and very brittle (especially cheap ones) with a low shear breaking point. Nails on the other hand are cut from wire and bend instead of shearing. Also they are a damn site faster to put into joist hangers than screws.
Many of the wooden gutters up this way originally had a lead lining, I think this is the case in most areas too. These have mysteriously vanished over the years and now most gutters round here are extruded seamless with a profile that is similar to the original.
+1 for replacing as soon as...
You could consider a contract lease. I'm not sure on the details but I think that you can claim a large percentage back against your income tax because you don't actually own the van so it's not a capital expense. Best talk to someone with some proper accounting skills to confirm this before...
He may be mixing his metric and imperial sizings up. If he meant a 4mm x 50mm this would equate to a 2 inch #8 or a "two inch eight". Best give him a call to see what he means.
Tony1851 - as I understand the OP it's the pitch on the hip plane that is different rather than the pitch rolling through along the main roof planes. If I have understood this correctly then the only difference would be in the length of the seat cut at the rafter foot which would be covered if a...
Irregular hips shouldn't be a problem for either the roofer or the carpenter.
Cutting an irregular hip is no more difficult than cutting a regular hip. You just have to do the maths and cut the correct angles.