Stone Slates slip

[Nick Odell]

A couple of stone slates on my roof have slipped. I'm guessing expansion and contraction from the recent weather may have had something to do with it. They were both near a roof window so I have just leaned out and hauled them back into place.

What holds a stone slate in position? Tiles have little nibs, slate slates have nails but as far as I can see stone slates stay in place through friction and an inherent disbelief in the laws of gravity. In other words: having hauled them back into place, is there anything else I ought to do to make sure they stay put?

Thanks,

Nick

[Fredxx]

They're usually nailed. Which also means that a slipped tile is problematic as access to the nail position is very limited.

For fixing slates in position, check the last minute or so of:

[Robin]

The few stone slates I've seen no longer in place had holes for pegs to keep them in place. I can well believe it's different with e.g. low pitch rooves. But is it possible you pushed back the bits of the slates that had broken off below the peg holes?

If there's any risk of one of the slates braining a visitor bear in mind you have now put on the public record your prior knowledge of their state of disrepair :(

[Adrian Brentnall]

They way they do it out here is that the slates have a hold drilled in the top end (the bit you don't normally see because it's covered over by the next slate up).

As to securing a slipped slate, our local man does it by pushing the loose slate up, then taking a 2" wide strip of lead and nailing it through the underneath slate into the timber.

Then ease the slipped slate back down into the correct position (in line with the adjacent slates), and bend the end of the lead strip up and over, so it grips the lower edge of the slipped slate.

Make sense? Adrian (South-west Ireland)

[Andrew]

It's standard fix for slipped slates, but tends to attract rooks and jackdaws because they like trying to steal shiny stuff, so they spend hours on your roof at 5:00 AM pecking away furiously.

[Robin]

Does that work on thick stone slates? The only time I ever saw them repaired (c.50 years ago) the broken slates that had slipped was bedded onto mortar. You couldn't see the mortar when the job was done. Possibly some jiggery pokery with adjacent slates involved as I wasn't watching from beginning to end.

[N_Cook]

Yesterday , while waiting for a train I was watching a pair of jackdaws pecking at something associated with a PV rooftop array. I could not see what they were attracted by as on the other side to me, non-conduited interpannel cabling? Pecking at insulation sleeving to the cables to provide a short at some point in future for the next rooftop PV fire, I could envision.

[N_Cook]

Westmorleand "slates" have drilled holes to take tapered oak pegs ledging on the lathes. I assume exposing the underside , in the loft , would show how many pegs had dried out ,shrunk and dropped out

[Nick Odell]

I've no intention of avoiding my responsibilities and after reading this thread I guess I will GALMI. Shame: I've not been too lucky at picking roofers in the past. It's not a matter of asking a neighbour for a recommendation: they've been fleeced by the same roofers who've fleeced me.

Thanks,

Nick

[Nick Odell]

Jolly interesting, thanks. I did that sort of thing to repair the slate roof on the property I lived in during the 80's but a)I'm 40 years older now, b)that property had a flat roof behind to break my fall whereas this has a three-storey drop and c)I don't think that technique works too well with stone slates or I'd have seen it more in evidence around here.

Nick

[Nick Odell]

That's interesting. I'll try and investigate further before GingALMI

Nic

[RJH]

I 'fixed' several slates from the inside on the old roof. But since it's been reroofed that won't be an option now it's insulated and a membrane's in place. Shouldn't need doing for a while though . . .

[Robin]

One small point is that it involved taking the slipped stone out completely for cleaning and inspection. So a lot may depend on whether they are relatively small and light or bloody great flags at the bottom of a diminishing roof.

Any chance of photos - if only to inform the collective "there but for the grace of ..."?

[Brian Gaff]

I bet there is a glue for this, somewhere!

Brian

[Brian Gaff]

I have a public liability part to my insurance, since these things can happen.

There used to be a wonderful glue called Urethane bond by dow corning. I have glued stone, asbestos and almost anything with that, sadly I've not seen it since. Its sort of transparent and a bit gloopy and came in a very robust tube. I suppose if you can get to the place from the inside there might be other ways to invisibly secure them. What I'd be worried about are the ones you cannot see. Brian

[Andy Burns]

A current product would be CT1

[Jonathan]

Silicone works very well. Jonathan

[Nick Odell]

Yesterday I was scoping out some other stone slate roofs[1] for signs of repair and it looks as if the mortar method is a thing around here. I had already managed to slide the loose slate back under the flashing so there's nothing to photograph right now.

The room's currently occupied by visitors so the plan is to have a better look when the room is empty again in a couple of days time. I'm thinking of pulling back the flashing and lifting the stone slate out (to slide it out from under the flashing is beyond my arm's reach). If the slate is intact but the pin is destroyed I ought to be able to fashion a replacement pin from a bit of scrap oak or something. If the slate turns out to be broken then to give it all a good scrub up and mortar the slate back down seems to be the way to go. I'm thinking caustic soda to destroy all the moss and other organic stuff but I'm open to other suggestions.

I'll try and remember to take some pictures but standing on an ladder, hanging out of a Velux window I might find I have other priorities!

Thanks again,

Nick [1]Probably got noted as a potential burglar as a result. Oh well...

[Robin]

On 26/07/2022 09:48, Nick Odell wrote: <snip>

Worried that my memory might be at fault I found this:

May not apply to your roof but sadly what it says about Small Scale Work suggests some jiggery and/or pokery required.

PS I first (mis)read you to mean the ladder would be hanging out of the Velux window with you on the end of it, and thought photos of that would be wonderful for the Wiki - and possibly valuable for the coroner too.

[N_Cook]

I used to keep a seriously nail-sick slate slate roof going by using copper wire stripped from house wiring, thru the nail holes in the slates, but that required loft access to tie the copper to the laths .