In the process of reroofing an outside toilet roof - mono pitch, using some old, fairly ropey, but still usable slates.
The original roof lapped the lead flashing under the slates. The builder on a job next door says I should lap it over the slates. I see what he means, makes sense, but it won't look as neat and might mean buying some more flashing. And the old roof remained watertight (AFAIK) for the 100-odd years it was sealed that way. Pics here:
I'm not a builder! The only similar job I attempted was a Victorian farmhouse slate roof butting up to a brick chimney.
I bought some lead roll (builders merchant and expensive). Folded the long lap using two lengths of angle iron in a bench vice backed up with some G cramps. The risers were cut out using tin snips and the tops folded ready for insertion in the raked out brick courses.
Installation was a pig of a job: having to avoid damaging the old slates while retaining the lead in the newly cemented brick courses:-(
Perhaps take your roof membrane up behind the lead? Easier with the old waterproof felt!
It looks like your old lead flashing is in vertical strips aligned with the lower part of each row of slates, but your new battens may not match the old rows. In which case I don't think it will work - lying underneath will need trimming and leave gaps, lying on top will not resist driving rain.
Yes - 8 strips of lead.
As it happens they do - slates are same size and hole positions as original.
I still don't understand how it worked before. Water drips down the vertical brick-inlaid flashing, under the slate, along the folded behind and under strips of lead, then returns back to the wall.
Admittedly that's quite a convoluted route for water to travel, but I'd think some gets through. I've added another pic of a mocked up start on the bottom course (which will be two slates deep).
I think it should flow down the slope of the roof, but you will get a wedge of water between the lower half of each tile next to the wall and the lead flashing underneath. With those edge tiles having a slight slope down/away from the wall, as they lean on the edge of the flashing and the underneath tile at the far side. (If you see what I mean).
Ah - good point. Hadn't thought of the slope. Thanks.
I am no roofing expert but noted whilst out and about this morning on similar roofs around here, on slates the flashing was tucked under whilst on concrete tiles particularly the corrugated type it was lapped over.
Wondering if the lead laps over the second row of tiles but under the first row of tiles.
That would still get rain to flow over the tiles, but perhaps hide the end of the lead flashing.
Cheers
Dave R
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