Roof insulation and risk of leaks...

[thunderhorse]

We're looking a buying another house. Assuming the roof (traditional canal tiles and older lats) is sound, we will convert the grenier into two bedrooms and insulate/plasterboard the roof from the inside. Obviously, if a tile slips, then water ingress into the insulation could be a problem. On the other hand, stripping the roof to put on a membrane could be far more expensive (and not easy to then know if a tile has slipped), but at least the roof should be permanently watertight.

Does anybody have any feelings on the subject? I have to confess to cost being a consideration if a membrane is not generally warranted...

Cheers, peeps. [:D]

[Chancer]

I have a similar dilemma with a roof in otherwise very good condition that does not warrant stripping, felting, rebattening and retiling.

There are at least 2 potential problems:

Driving snow will enter under the tiles, dependant on the volume and the ventilation this may or may not cause a problem, after all your roofspace has probably already suffered this several times without causing damage to the ceilings underneath.

Evidence of future leaks will be hidden until damage is done, by the time you notice that your paint is beginning to peel, the insulation and plasterboard will be already sodden.

You can buy reels of insulation with a plastic film attached for this application, Isover of St Gobain being one who have a good detailed catalogue with lots of pictures www.isover.fr

In principle it should work but for any proper leaks the water will always find the easiest vertical path and will probably enter the room via the purlins.

Do not under any circumstances consider the sprayed foam system favored by the get rich quick commerciants, you will find lots of good advice regarding that by using the search facility.

Whatever solution you do choose please post an update so that I and others could benefit from your experiences.

[Payrac-man]

Hi

 

I have just finished stripping and felting. The felt was cheaper in UK, I also fitted felt support trays http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=101893&ts=08349&id=36622

and anti bird mesh.

I personally think the cost 2000 euros well worth it.

 

All the best

 

[Chancer]

I remember chatting with a retired UK immigrant on this subject, he thought he was doing me a right favour by recommending the british crew he had imported to spray the chemical foam gunk inside his roof, "and they only charged me £9000 cash!" I nearly dropped my apero!

He went on to say that the materials (traditional felt and battens) alone would cost more than that in France, I said that I would allow a maximum of 500 euros for it and did he realise just how much it was going to cost him when he eventually had to get the whole lot ripped off and replaced?

[shimble]

stripping the roof should not be expensive, the tiles are easy to work with, and the cost will be the membrane, and maybe the wood if you are not able to reuse it, nails, and time. I wouldnt use bitumen based felt as they are better products on sale in france. The cost will be a lot less than ripping out old insulation, placo, and then re-doing the roof anyway when it leaks...... ide rather sleep in a bedroom i knew was waterproof than hope it was waterproof..... just my thoughts..... but if your going to do it why not do it properly?  oh and if they only wanted nine grand cash for the foam ide have done it properly for that too..... ide even wear a beret for that money.... some people......