Slating felt or not!!!

[tonyg]

We have property in south west france which we are waiting to move to. In the meantime the roof has sprung a leak. We now have to decide the best way forward. Why do the french not use slating felt? Should we just stick to the close-boarding already used? If we used felt as well would it get too hot, would the felt melt? If felt is the way forward is there a supplier that can compete with the cost in England?

thanks Tonyg

[VJ]

Tony

I have just had two roofs done in the sw region of France and they were done by a very respected Artisan

The Garage roof was First planked(voleige) with poplar (Chestnut is to expensive) and then a layer of papier (as they call the felt) was put on and then old multi sized reclaimed slates

The house roof was stripped off and then we put on new type air flex insulation

counter battens,for air circulation boarded and then a layer of felt with the slates put back

It was overseen by an Architect and conformed to all regs and is guaranteed

So I do not know where felt starts and finishes as regards to when it is used or not

Certainly the people in the area have felted roofs as I have inspected others when the statement was previously mentioned.

There is a product called Tyvek which allows the roof to breath which can be used instead of papier

Hope this helps

regards VJ

[Nick Trollope]

[quote]TonyI have just had two roofs done in the sw region of France and they were done by a very respected ArtisanThe Garage roof was First planked(voleige) with poplar (Chestnut is to expensive) and then ...[/quote]

Not around here (dept 22). I can't think of a single house that I have seen re-roofed (plenty) except with battens, clips and slates.

I was always told that those in the South didn't use roofing felt because of the temperature variations, which isn't anything like as severe here. One of those daft regional "tradition" things, I guess.

 

[Dave&Olive]

this might be a long one ....

ok, lets think uk for a moment early days slate will give a rain repelant depending  on the roof angle , /\  . the brits built at a lower angle and then sealed the bottem of the slate from the inside with cement or plaster to allow for adverse weather ie driving rain blowing water up the slates or , snow thawing and then freezing forming a dam on the roof and then thawing again letting in water .         ( hold this part for a moment the french just built steeper roofs )

              so step on a few years and reslating is required so insted of sealing the slate from below the brits fitted felt ( which will melt in the french summer) this caused condesation problems in the roof space and the wood started to wet rot .

          so a few years on they fitted roof vents and breatheable felt.

           so according to the wind and rain " a pun " sorry you do not need to fit it, but with changing weather conditions global warming ect for the extra cost............

                                dave

[Macker]

'Felt' is a bit of a misnomer. The plastic breathable membrane that is becoming more and more commonly used throughout France is caled 'ecran sous toiture respirant' and will not melt under any conditions. There's lots of different makes and you can buy it in any Brico or builders merchants. For best results you should board the roof with at least 20mm planks. Nail vertical battens along the purlings and then lay the 'felt' starting at the ridge so that you have a half sheet on either side and then lay each subsequent roll with at leat 30cm overlap. Then nail the horizontal battens (the ones you will clip/nail your tiles/slates to) where they cross over the vertical battens thus securing the felt and the roof. Then lay your tile/slates. Finally, concrete on your ridge tiles and point in the edges and overlaps if you have any. If you follow this method you will have a roof that should be sound for at least 20 years as opposed to the normal life expectancey of 10 years for most roofs in France.

[dinks]

Well what can I say to Dave’s comment,

 

(the brits built at a lower angle) ??? Wrong

Slates can be used down to 17 degrees some times lower if you increase the head lap

 The average roof pitch in the uk is 45  degrees and up !!

Felt was introduced into roofs in the uk to prevent the ingress of the real fine snow in the early 20s/30s and as a way to sell it  was said to reduce drafts .

It started as two paper sheets with a fine layer of bitumen in-between that had to be draped   in-between the rafters at least 6”to 8”due to the fact that it would contract  and split if not draped .

Then some time later full on bitumen felt ( 1F as its called in the uk ) was introduced and is still used to day .

(to cut a long story short) after 30 years in the roofing game in the uk And not to bore you al with the facts of this and that.

If your going to the expense of having your roof re-done (1) get it insulated

(2) get it felted

(3) if you can afford to have Tyvec as its bomb proof  but not used  much in SW France But costs are high , but then you pay the price you get the best

[Ernie]

..and for old tiled roofs, what about that 'onduline' stuff? corrugated plastic, basically. is it any good?

Ernie

[VJ]

Thanks for that Dinks looks like I got the pucker job.

Not certain about the Guy who reckons you have a roof for 10 years My Guy is telling me 100 !!!

VJ

[Macker]

VJ your roofer is right, a properly laid slate roof should last for 100+ years, I should have specified that I was talking about the traditional teracotta type tiles when I said 20 years due to the fact that they simply become porus after that time.

[Dave&Olive]

[quote]Well what can I say to Dave’s comment,

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