insulating a slate roof

[hoverfrog]

We (will soon!) have a slate roof - the slates are hung on the batterns with galvanized hooks, and all the roof timbers look OK.

What is the best way to insulate the roof so we can convert the loft? There does not appear to be much (if any) water ingress so far, but we would not want to seal them off completely and not know what was going on behind so perhaps something waterproofing would be in order?

[Tim_Quincaillerie]

I work for a roofing/carpentry firm here in France.......and I think your best option is to lay felt before the battens( lattes ) get put on the roof and afterwards ( if space permits) put 180mm of laine de verre ( glasswool ) between the joists ( which should be 56cm in between. Or use the new Isoover aluminiun foil that has equally good insulation effects.

 

As regards to leaks from a newly slated roof, does not really happen unless the carpentry of the roof as has not followed procedures of the angle ( normally 45 degrees on a new house) Anything shallower than 30 degrees  is usally a problem ( if my memory serves me right)

[hoverfrog]

[quote]I work for a roofing/carpentry firm here in France.......and I think your best option is to lay felt before the battens( lattes ) get put on the roof and afterwards ( if space permits) put 180mm of la...[/quote]

so that does mean taking off all the slates to do anything? that was what we were afraid of, but we couldn't see a way round it

Looks like we'll have to wait for the summer then! Probably be about right once we've sorted out planning permission!

OH has plans to put our four poster bed up in the 'loft' with decent curtains round it for insulation - although I think that might be a bit chilly even so

[Peter]

You have to be really careful filling the gap between rafters because of condensation problems. Ideally one should leave a air gap between the  roof and the insulation. If you have to use this method use a ridged foam type insulation. See HMSO publication Thermal Insulation Avoiding the Risks.

Good luck

[Bobc]

"so that does mean taking off all the slates to do anything?"

With thin metal-foil backed insulation, correctly installed you can probably do the job from inside without needing to take the tiles off.

If the tiles have only recently been laid then your roofer should have thought of the question of insulation in advance.

The other posting re airspace is important - if you would like to e-mail me at the address in my profile I will give you some links to the sites of the foil-backed insulation products that we use for loft-conversions, etc.

Kind regards,

Bob Clarke
http://perso.wanadoo.fr/grindoux

[hoverfrog]

Thanks for the encouraging replies - we would obviously rather not have to remove the tiles, but are concerned that if we insulate from the inside without putting a waterproofing layer that water could get in without us knowing and rot the batterns. I guess that when you have have a layer of felt under the batterns you are making holes in it anyway when you nail the batterns back on!

The system of hanging the tiles over the batterns doesn't appear to lend itself to having any roofing felt or similar under it as the hooks would penetrate it, and although there's a lot of info out there about traditionally tiled roofs I couldn't find out much about slates with hooks.

The prospect of having a single layer of slates between me and a Limousin winter is a chilly one!

[Dave&Olive]

the ideal situation would be to use a breathable membrain fitted directly to the joists with virticle batons then fit the horizontal batons to fix your slates to this would then give you the air vent to stop condensation forming you could have then insulated up to the felt fit a vapour barrier and plaster boarded                 my rsm used to walk round with a baton virticle how the hell can i learn to speak french when i canot speak english,good job my first language is welsh...........

[Ewa]

Friends in the UK have recently had a spray form of insulation 'installed'. Is this sort of insulation not feasible? If companies in the UK give a 25yr guarantee it would indicate that this was a good alternative. Our friends were told by their mortgage company that they had to re-roof due to lack of insulation (could have been other things too, I'm not sure) but they did this and it was only something like a quarter of the price - they then used plasterboard to cover it up and carried on with usual plastering etc.

Any thoughts??

[KevinH]

Hi

We are in a similar situation. We have bought a cottage in Normandy and want to convert the loft. The roof timbers are perfect and apart from a couple of slipped tiles (which we intend to replace with some air vents) the whole thing is water tight.

Because of this, we are reluctant to take off the tiles to fit a membrane/felt underneath, hence the lookout for alternative methods. One route that we might go down is painting the inside of the tiles with a traditional lime and cow hair mixture. Sounds bizzare but there is an actual product for this purpose. We would then insulate and plaster after this.

We would be interested to know of anyone else in a similar situation

Thanks all.

[hoverfrog]

we'd be interested in finding out more about this - got any links?

[Iceni]

A lot of info on this was in the archives. This has unfortunately been lost. The views on felt, foam and other UK methods was simple, this is not the UK, see what your neighbours do and do the same. We have used the foil layered insulation with good effect and we will also be sleeping up in the loft when the rooms are finished. The foil insulation is made in France and is easy and clean to use.

Something I can remember about felt was that it was not used because it tended to melt in the heat and I also think that the foam became a 'playground' for mice - which having stayed in a gite with mice in the insulation is something you don't want to hear all night (they were in the walls and roof).

Hope that this helps, again it is a shame that the archive has been lost.

[Blackadder<IMG src="http:forums.livingfrance.comimagesline.gif"><BR>Blackadder<BR>Keighley and Creuse]

I think Iceni is bang on with the 'not in england, do as the french do'....

We recently had to take off our tiles and place a damp proof membrane. We used a clear reinforced plastic stuff. Do as has been posted and staple the membrane to the purlins Do NOT pull it tight, leave a dip in the plastic between each purlin to allow any water ingress to flow down and out the bottom. Then place the battens back on and then the slates/tiles.

Then use the incredible foil insulation stuff they have in Mr Bricolage at 75 Euros a roll of 1.5 m x 10 m. Easy to fit single handed, staples in place and leaves you a nice 50 to 75 mm air gap between the outer face of it and the inner tiles.

[Springer]

 Totally disagree with the above.

 Look into the products rather than just assume that the locals are right.I've used foamseal on my roof in Normandy and it offers far greater benefits than your average insulation, so I would highly recommend it.

As for as in France do as the french I'll just say this. Have you ever bought anything over the internet from abroad (assuming you live in the UK) because it was better or cheaper. There is a worldwide market out there and as long as the research is done then there should be no issues with using it.

John

[Moulin]

I totally agree with the comments on being careful due to heat, every Autumn I have to re-seat the Lead Flashing that has distorted over the summer. You could literally fry an egg on our roof at times!

Equally it’s true that some English products are superior to there French equivalent, take paint for example, so it’s worth looking on the net to see what’s used else ware including other parts of France.

[hoverfrog]

lots of food for thought...perhaps talking to the neighbours about it to see what they have done would be a good ice-breaker if I gen up on the french terms!

The thread on green (or not so) oak in another forum was interesting too - we will have a quite large oak that the neighbour apparently wants removed as it's on the boundary, along with quite a few sweet chestnut trees, so perhaps we'll be able to use them!

[Dave&Olive]

looks like we are all learning from this posting . mix and match is the answer use the best of british or the best of france which ever suits and use them together