Spray-on Roof Sealant?

[Sterillium]

Has anyone had any success with a spray on roof sealant?

I have an outbuilding where an old stone wall joins a pitched roof, and it's leaking along the join. Because the wall is very old and lumpy, with around 100 years of spot repairs and replaced stones it's impossible to paint.

I'm looking for something I could spray on the wall along the length of the join that will lock water out until I can get the wall and roof properly repaired or replaced.

Imagine trying to waterproof a dry stone wall that was assembled by a drunk... it's a bit like that.

[Cow Corner]

Without a picture it’s hard to be specific, but it sounds like it’s possibly a rare occasion where I would suggest either flashband or if you want a liquid repair, Acrypol or equivalent.

[Byker28i]

I used Thompsons 10 year roof seal on a flat roof that was cracking. Put it on with a roller, two coats. Looked great and made the roof look like new.

[OutInTheShed]

Sounds like the problem is not just the flashing at the roof/wall joint, but rain penetrating the wall and going down inside the wall, behind the flashing?

I've used Thompson's to keep most of the rain out of a brick wall in the past, it was pretty successful, but only after repairing the pointing.

trouble is, slathering water repellent stuff on the wall can make it harder to repair properly.

'Repair' may not be the right word here, it's an outbuilding with a 'lean to' roof, it may never have been built with high expectations of keeping 100% of the wet out.