On 25 Jun, 11:56, "jon" wrote:
I'm thinking of getting an attic conversion. The roof is welsh slate and in
very good condition, timbers fine, nails ok and ridge tiles etc. However, as
it's the original 1930's roof, there is no felt.

The question is, does it matter if we get an attic conversion. I have asked
all 3 companies who have provided quotes ( all reputable, with good
recommendations) and they've said it should be ok. Any reason why they
should be lying. Is roofing felt a must if you're having an attic
conversion. Can you fit felt without riping off the existing roof, or am I
just asking stupid questions.

TIA

Jon

I've always been a believer that in Scotland, where you had 'proper'
slates on sarking, that felt was not necessary at all and that the
presence of it now in Scottish housing is the influence of English
practice where it is necessary for tiles hanging on battens. The
problem with felt and sarking is that any moisture ingress can get
trapped and result in rotting the sarking, together with the major
headache you get with all felt of being unable to assess where a leak
is occurring.

In many ways my opinion was reinforced when working on a barn,
probably 150 years old, where clearly there was no felt and apart from
areas around the skylights, there was no deterioration in the slates,
nails or sarking. We were using it as workshop and did discover that
in a snow storm, fine snow did blow under the slates and land on the
ceiling insulation, but of such little significance that it was more
of curiosity than anything else. What it did show was that there was
airflow through the roof to keep it dry and ventilated.

I'll leave it to Jon to decide quite how that fits in with his
requirements!

Rob