Hi!
I am the proud joint-owner of a large and rather old lead-covered valley between me and my (semi) next door neighbour.
It is well in excess of 50 years old and has been laid on a wood base which was covered with two layers of old bitumen roofing felt. Over time I suspect the felt has melted and fused to the lead, cracks in which have been repair with some (unidentifiable) sort of tape. There are newer cracks (probably due to thermal movement) of up to 600mm long by
Sadly, that may be the onbly way to do it properly. You MUST run the leading up under the tiles/slates for at least a few inches.
If the valley slopes significantly, then 2 meter long (no more, or they buckle) strips of lead beaten into a U shape and overlapping a significant amount - 10" or so - wiill work. They should run at leat 4" up the sides under the tiles etc.
If its a flat valley, then you have a problem. you may need to solder it all together and hope it doesn't move too much, or fold teh adjacent sheets together and beat the joint flat, but it will always puddle a bit.
Mmm. You could lay up fiberglass and polyester resin as if it were a boat. The trouble is as always making sure it runs up under the lower slates or tiles.
Maybe you could fiberglass the base, after cleainng off teh old stuff, and after laying strips of lead fromn up under the tiles onto the valley floor.
Faced with constructing a valley between my new garage pitched roof and the wall of my house I decided to avoid lead as it would have to be laid in
1500mm lengths with steps of at least 25mm - a pain to plan and make. I opted to form the box valley in 18 mm WBP plywood with a 1 in 40 slope, and laminated two layers of fibreglass generously resined. I ran the valley 225mm up the garage roof and 100mm up the house, then flashed with code 4 lead on the house side.The Building Inspecter was most impressed !
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