lead flashing peeling at joint

It is normally chased into the wall by a depth of about 1" and made good with mortar. If it looks like it has peeled off, it could be it has split where it is chased into the wall.

Or you've been visited by a few members of the Caravan Utilising Nomadic Travelling Society in the night, and they got scared off before they could rip it all out?

Never seen that, but the mortar does eventually fail due to the lead expanding and contracting in the sun, allowing the lead to pull out.

Report back exactly what the failure is, to get more help with fixing it.

Well yes - but then that would be likely obvious to the OP?

It may not even be lead, but that self adhesive flashing with a metal layer.

The top of the roof meets the two-storey vertical wall of the main house. Where they meet, there is som

e lead flashing. One strip of flashing is peeling away from the wall at one end, where it meets the next strip of flashing (about six inches has peeled away). The flashing looks undamaged. What is the best way of reattaching it?

Assuming it actually is lead:

As an aerial installer I used to see this every day. It's common, especially on houses built between about 1975 and 2000. Sometimes it falls out when you're looking at it, then you get the blame! I've repaired a few of these. Rake out all the old mortar. Get hold of some strips of lead about 2" wide and roll/fold/bash them to make fat 2" 'cigarettes' with a diameter rather more than then the mortar joint width. Hammer them so they have a bit of a wedge shape. Put the flashing back into position and use the lead wedges to hold it in. Drive them in endwise between the lead flashing and the brick above. Mortar along the joint between the wedges. Use a very firm mortar mix, so firm it's a bit hard to push it into the joint. A piece of wood the thickness of the joint's width will help.

Bill

I meant sideways.

Bill