Slate roof and sarking.

[T i m]

When our sate roof was about 100 years old we had it stripped, lined and the original slates re-fitted because 99.9% of them were still fine.

The reason most of them that slipped and hence got broken was because the nail(s) failed.

A neighbour on the same terrace has just had hers redone and it looks like she's used new 'synthetic' slates of some sort and a sarking of what looked like DPM, a heavy blue polythene? I think mine might be more of a heavy waterproof fabric?

I did text her a question [1] re if they were synthetic and what was happening with the old slates as I believe they are quite valuable and often sold for more than the new / synthetic ones? ;-(

Cheers, T i m

[1] She's not replied yet. We are good neighbours and I did suggest a different roofer to the one she's got (as his dad and now he, has done most the roofwork in this area, inc re-tiling my Mums house).

I'm pretty sure he would have re-used the old slates and given they are already a few million years old, another hundred shouldn't be a problem? ;-)

[Robin]

Not all slates are the same. We replaced 110 year old slates with "synthetic" because many were delaminating. Quotes to refit with reclaimed slates of similar appearance and same size were prohibitive. And the quotes from roofers were all on the basis of them having the slates to sell on.

We also used breathable membrane (but in addition to ventilation).

PS

If you are short of Os and Ts I can email you some.

[Kellerman]

Having just had my house roof done - replacement Welsh slate was far too expensive. Quotes/Estimates/Guess's of double or triple the eventual price were banded about. The quality of the slate used does vary, small thin pieces with poorly trimmed edges only fetches low prices - particularly if its contaminated with moss or cement with surface marks. The best stuff - larger, thicker, clean, even colour with very neatly cut edges fetches a better price. The advice from our roofer was that the slate was too poor quality (1920 agricultural semi way-way-way out in the Fens) to be worth the effort of cleaning and grading.

[Roger Hayter]

The first few million years were under pressure, dry and anaerobic! Our old slates (age unknown) were softening, delaminating and brittle and were not easily re-usable. We ended up with Spanish slate, in a spirit of European co-operation, and relative cheapness.

[T i m]

<snip>

I appreciate that, same with the location they are used etc ... but this instance is 2 doors along, presumably used slates from the same batch and so should last as long as ours have? Even after all the wind we had recently I don't believe we have lost a single slate?

Was that common to houses around you?

Yes, I understood that could be the case *if* you couldn't re-use a reasonable percentage of the original slates.

Ah, that sounds like it could be the deal here then (give how intact

99% of her slates still were). My only concern was that she was being 'ripped off', being she's on her own and seems a bit 'dipsy'. ;-(

That was part of my question, *should* such sarking be breathable and if so, is there any that looks (from the road) to be just polythene sheeting?

I am mainly only interested because we sorta promised her parents (who live a long way 'up Norf) that we would look out for her and for me that's hoping she's not being ripped off (whilst at the same time is it's her money to throw away, *if* she has all the facts etc).

What sort of guarantee did the synth slates you used have OOI?

Cheers, T i m

p.s. If I had loads of money I had to 'lose', I think I'd refit the front of our (South facing) roof with solar (PV) slates, and a battery even if it meant having a parallel mains system that only powered a selected range of things (or things that could automatically switch to 'solar' if the capacity was there).

[T i m]

<snip>

Funny, I was talking of our 'cultural holidays' and I think we visited a slate mine when staying at Porthmadog (up the Ffestiniog Railway)? I think we also saw a demonstration of some slate being split and trimmed, very interesting. ;-)

;-(

Ok.

Makes sense. From memory, when they stripped our roof, probably 95% of it was just the clean stuff and may have been more if we hadn't been OOT. Even the cement that was on there would probably have brushed off with your hand. ;-)

Understood.

However, next door (but one) isn't like that and from the state of her slates before it was stripped, and ours still now (and the rest of the terrace), I can't see why they weren't re-used. Unless (as has been suggested elsewhere), that the cost of the work has been subsidised by the value of the old (good) slates?

Cheers, T i m

[Roger Hayter]

xenophobe

[T i m]

<snip>

Well yes, but still, the ones on the houses either side of her all still seem to be intact ... (even after the batch of storms we had recently)?

Softening and brittle?

Ok.

;-)

I guess these 'different looking' [1] synth slates might outlast her ownership of that house and so she can leave any longevity issues to someone else. Could be justifiable if it was down to having to replace a failing roof and the value of the old slates made the job doable but I don't think that was the case (it wasn't failing in general, just a few had slipped because of failing fastenings).

Cheers, T i m

[1] I think the new synth slates nearly 'stand out' (as being different) as much as solar panels do ... but not quite as bad as those who have replaced slates with red cement tiles. ;-(

[Robin]

On 15/03/2020 12:59, T i m wrote: <snip>

Marley /warrant/ their Eternits for 15 years. But roofers here reckoned their /expected/ life was 30~60 years - and towards the high end in London weather. For comparison the most expensive natural slates we looked at were warranted for 30 years (10 for colour) and expected to last 100+. (But judging by the number of loft conversions in the past

10+ years half of the roof will be gone anyway as soon as soon as there are new owners.)

[Dave Plowman (News)]

Going to depend on how many slates need replacing. And how easy to get matching spares at a decent price.

My roof was tiled when I bought this house. Not sure if original, or not. Had it redone using artificial slate which still looks good some 30 years down the line.

[harry]

Substitute slates were first asbestos cement and later "other fibre" cement. In the USA and coming over here are shingles made out of a variety of materials.

Nothing outlasts Welsh slate with copper nails.

[Dave Plowman (News)]

Except that most used galvanised.

[Roger Hayter]

Craters were soft bits had washed out, but very prone to crack when handled.

[T i m]

Hmm, that doesn't sound very long does it? ;-(

Ok. Not unreasonable then, given how cheap they are (by comparison).

Oh, I thought it would be longer than that.

True.

Cheers, T i m

[T i m]

<snip>

Update: Neighbour took a package in for me yesterday and dropped it in later in the day (no one left a card) and it appears she also went for Spanish slate. She added that the roofers had taken the old ones away but didn't mention if they had given her any discount towards them (I was also on the phone at the time so didn't get the chance for any further chat).

I wonder how long, (if ever?) they will 'tone down' to match the old ones either side of them (FWIW etc)?

Cheers, T i m

[harry]

Only the cheapskates.

[harry]

No, it's used everywhere in the UK. The slates vibrate in the wind and wear off the galvanising under the nail head. The nail rusts through and the head comes off.

It's worst where the nail hole has been made with a traditional slater's tool and left sharp edges. ie the spiky thing

[alan_m]

A commercial property on the corner of the road where I live was re-roofed with synthetic slates 20+ years ago. Judging by the number of these slates that have slipped in the intervening years I guess that they did not use appropriate nails.

[Chris Hogg]

A lot of wet-laid slate roofs down here, aka scantle roofs. Mine was wet-laid in 1960 - used wooden pegs on thin wooden laths - still OK. e.g.

Other roofing firms are available

[Dave Plowman (News)]

You can always find a bodger if you try.