roofing felt - is it needed

[jon]

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

[The Natural Philosopher]

The primary function of the felt is to provide windproofing and help avoid slates being ripped off in storms etc. It is not (as many think) there to keep the rain out!

If you are putting what amounts to a windproof scheme inside, you dont really need it.

[Guy Dawson]

We have a house on the west coast of Scotland and wind is a real issue there. If the wind can get into the loft space of a house then it will exit any way it can. That includes blowing out roof lights and tiles.

Guy

-- -------------------------------------------------------------------- Guy Dawson I.T. Manager Crossflight Ltd [e-mail]

[Roger]

The message from Guy Dawson contains these words:

I was under the impression that it was a long standing tradition in Scotland to board the roof before slating. That was certainly the case in the only bit of roofing I have ever had a hand in in Scotland. That was back in (IIRC) 1961 near Strontian. That is too long ago for me to actually remember if the roof got felt as well as boards but I don't recall any.

[robgraham]

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

[Guy Dawson]

My grandparents house in Hampstead - they're dead, the house was sold to give the tax man his fair share - had a wonderful roof. The boarding in the roof was a thing of joy!

The 1960s extension to our house in Scotland is boarded but I'm not sure about the original 1920s part of the house.

Guy

-- -------------------------------------------------------------------- Guy Dawson I.T. Manager Crossflight Ltd [e-mail]

[The Natural Philosopher]

That is certainly the very best practice in windswept areas.

[jon]

From all the replies, it appears, as was said by the prospective contractors, that it's not essential.

thanks all,

Jon

[Graeme]

In message , Roger writes

Our house is NE Scotland, and yes, the roof is boarded, below the slates. No felt, though. That is not surprising, as the roof has probably not been touched since the house was built around 1860.