old slate roof advice please

[Simon Wilson]

I have a stone built house with a (slightly leaking) slate roof that I need to fix. The slates are held on with funny nails, and no roof felt (it's a French thing apparently.

A couple of slates have moved but generally the wood etc. seems to be in good nick.

Once I get the leaks sorted I'm thinking of doing something like this:

anyone have any experience of it please?

It seems a bit expensive, but looks like it could/should be a do it once and forget job. Does anyone know if diy is possible, or is it a professional only job? Recommended suppliers?

TIA

[Dave Liquorice]

Not experience but my opinion is that without any sarking water will get in and onto the timbers. If they can't dry properly and quickly 'cause they are coated in foam they will rot.

Get the roof properly repaired and consider lifting the slates, fitting a modern breathable sarking and reusing the old slates. Some will inevitably not survive being lifted but unless they are in bad condition on 10 or 20% will need replacing.

[dom]

The downside of those treatments is it's non-removable - and if you get a subsequent leak under the tiles, the water may be trapped by the foam and the rafters slowly rot.

[meow2222]

p://

Its a classic no-no. For more info see

for more detail ask on the period property uk forum

NT

[Dave Liquorice]

And another thing that I forget earlier, when it comes to sell and buyer or surveyour will instantly think "What's it hiding?" or "the roof must be bad if it's had to glued back from the inside".

[George (dicegeorge)]

I too have an old house with slates, some leaks, but mostly patched with tape a few years ago.

i've been following discussions on this group for almost a year, learning lots...

It has been shown to me that the nails in my roof are rusty, so patching the slipped slates is only temporary, they've all got to come off and go on again.

i'm too unskilled and clumsy and scared of falling (again) to do it myself, i will however do insulation, ceilings etc, and am clearing away the old lathe and plaster and dirt and ancient unused pipes and wires to make it easier for them.

sarking/ felt of a modern kind is recommended.

some recommend the scottish method of putting boards on the rafters, then battens, then slates, but i think this probably an unnecessary expense for herefordshire- i have a lot of roof to get done.

Maybe boarding is a good idea for london where insulated roofspace is valuable

some say the nails should be aluminium, not copper.

the spray-on foam people guarantee their job for 25 years, but will their company exist in 25 years time? and anyhow this building should last hundreds of years,

i dont need the roofspace so i'm going to have a cold ventilated roof space, with insulation above the ceilings.

So I'll be able to walk around in the roof and look for leaks (but not sure about this - with no felt now i can see light through the gaps where slates have slipped, and wet patches underneath them, but with felt any dampness will flow down the felt and be invisible to me, hope this doesnt mean the timbers will rot... )

and im gonna have a few skylights put in, perhaps facing north so not too much burning sun, but how to insulate them i dont yet know...

[george]

[Dave Liquorice]

The strip and replace will mostly take place from the outside, after all that is where the sarking, battens and slates are... There will be all manner of muck falling onto the boards, ceilings or insulation though so making it clean is a waste of effort as you'll have to do it again when the roof is done.

Tyvek is translucent so daylight from slipped slates is still visible in a darkened loft sapce.

Any new timbers should be pressure treated but anyway there is ample ventilation under the slates for the battens to dry if they get a bit wet. The sarking keeps the rafters dry.

[The Natural Philosopher]

Only second hand, and the general advice is that of all the things you can do to make a house roof unrepairable ever again, and render the house unsaleable, this is no 1.

[The Natural Philosopher]

sarking is not for waterproofing, its for windproofing. Ive lived under an uninsulated unsarked slate roof and it was dry as a bone, but with no loft insulation either it was the coldest place I have ever lived in. In winter..in summer..it was the hottest.

That's good advice, if given for the wrong reasons. If you want a warm roof, fit celotex between te rafters and board over. That IS a DIY job.

[mail]

this:

> Does anyone have any experience of it please?

Dear Simon I agree with the other posts that this is just about the last thing to do for the reasons given - lack of reversibility - rot not to mention future sale risk. Chris G

[Dave Plowman (News)]

What you're doing is sealing in any future leaks on a roof not designed for it. Timber needs a good air supply to prevent rot.

[Simon Wilson]

Thanks. Looks like getting it repaired, consider sarking and diy fit insulation board is the way to go.

[Simon Wilson]

Thanks for the advice.

[Simon Wilson]

aye. Seems to be the common thought. Thanks for the reply.

[Simon Wilson]

this:

>>> Does anyone have any experience of it please?

Thanks for the link.

[Simon Wilson]

Thanks for the advice. I think it's a resounding 'no' :-)

[Dave Liquorice]

It's a secondary waterproof layer, water will get through a slate roof with the rain/wind in the right (wrong?) direction and strengths. And once a slate slips or fails water will certainly get in.

Keeping the wind out of the loft is a good point though.

[stuart noble]

Except to say that a house at the back of us was done 20 years or so ago and, although I haven't been in their loft, there don't appear to be any loose slates. If it was, say, 25% of the cost of re-slating, I might be tempted, but not otherwise.

[Andy Hall]

This isn't really the equation, though.

It's really a gamble with the cost of a complete new roof including timbers. Effect on saleability can't be measured. If I were a buyer, I would either be walking away or would be wanting to deduct the cost of a complete new roof and timbers. That would take the status back to the point of what it would have been like if fixed properly in the first place.

[stuart noble]

The building in question has changed hands at least twice since it was done, and is currently occupied by a firm of civil engineers with swanky, sweet-smelling offices, so I think we can assume nothing major has occurred aloft.

Our house was originally part of the same property, and we decided at about the same time that re-slating was the way to go. I don't regret that but it does show that it's maybe not quite so cut and dried an issue.