I'm hoping the collective ukc van conversion and shed building experience can get us out of a hole...
Mum and dad live in a very small house, which they make up for by building various sheds and outbuildings. Dad seems to have CSBD - Compulsive Shed Building Disorder, I am showing worrying early signs of inheriting this
An octagonal wooden building has been constructed on the front lawn (because we like a geometry challenge). It's made almost entirely of recycled and reclaimed materials and so the budget is not vast (so far, about 400 quid of total expenditure, mostly on roof flashings).
The roof is wooden, made from fencing panel timber in eight long triangles rising to a central point with a solid finial. The joins are heavily filled with caulking mastic and we have some quite smart flashing to keep the rain out fastened over the top. Which appears not to work. Beneath the timber there is building paper (overlapping) and then foam insulation panels. Water is running down the internal structure - it's hard to tell how much is condensation and how much is leak (but I suspect a lot of the latter). But it has been really, really wet here for the last week or two..
The aim on the inside was to have the lower part of the octagon roof to be cedar tongue and groove, with a central interior upper octagon being plasterboard which my very artistic sister was planning to paint on. Lighting will be via LED strips on a small architrave running round the interior circumference.
The size is the maximum size the planning officer has allowed, so it is all "size legal" I gather.
So my question is - how do we fix this? Is condensation likely to be enough to explain the dampness inside (it was running off the builders paper so not insignificant)? Do we have to redo the roof from scratch? I was wondering about lifting the flashings and inserting more caulking to any visible gaps, and then possibly using some thin closed cell foam compressed beneath to try and fill in any gaps that might allow wind blown rain to come up under the flashing (e.g. a particularly squidgy thin karrimat type foam)? If it's all just condensation, do we need another layer of tyvek or similar under the foam insulation and a bone the cedar or plasterboard?
Thanks for your thoughts
cheers
b