Help re closed cell insulation and damp

[Build2022]

Any help greatly appreciated. I'm 3 weeks from exchange on a property and have just had the survey back. An amber reading of damp on the newly renovated bathroom ceiling - whole house been renovated and empty for 6 months so not damp from use. Also on upper wall of bathroom and on kitchen ceiling directly below bathroom.

 

There's foam insulation between the rafters and I'm going to go back and visit myself and try and get some readings of the timber in the attic.

 

I can't get a roofer to look at it for love nor money at the moment so will need to make a judgement myself. 

 

I'm thinking worst case scenario. My question is, I'm in Devon, how much very roughly to replace the roof and rafters inc tiles etc if it turns out it's leaking and rafters are damp? The house footprint is 5.3m x 7m. I appreciate this is a 'how long is a piece of string question but I'm after a very rough idea - 10k, 50k?

 

Thanks

[tonyshouse]

I hate that spray foam, trying include the loft into the heated envelope of the building is a bad idea.

 

I love the dragon tie! The rafters rend to stay dry, if tiles leak then battens get damp, go mouldy and rot unseen. 
 

was a damp meter used to detect “damp” in the bathroom?  I hate damp meters, they measure electrical conductivity not damp.

 

if you can get back in and collect a sample I Nan analyse it and tell you % moisture to within 0.1 of a percent, bag it in poly, double bagg and send by post. Sample should be it here all wood or all plasterboard so send two, a 20th of a teaspoon would do. 
 

I doubt damp and unlikely to need a new roof, all the joists look good but are all thermal bridges. 
 

roof unlikely to be leaking apart from through or round the chimney