Valley gutter lining - what should i do?

[nalakitty]

We got keys to our new house last month and found out the valley gutter is uneven and leaking. Nothing was picked up in survey. surprise surprise 😂

Recommendations from roofers (it must be a slow market as we are able to get quite a number of responses) range from fibreglass, felt, lead to monoseal. ive discounted fibreglass as its not really durable. Do you have experience with any of the others? And how much did you pay?

I second the advice from @Diyextension that a one-piece aluminium gutter/lining would be a good, reliable solution. I've worked on refurbishment/remediation projects on commercial buildings and that's the sort of solution I could imagine our architects proposing.

The trouble you'll have is getting the gutter in. Not sure if it's possible to do without taking the roofing sheet off, and anything that can be done with the roof in place may well be a bit of a bodge - might work, but might not. On one building where removing the roof and disrupting operations in the building would have been very expensive (think, e.g., vehicle assembly line beneath), we re-covered an entire side of the roof over the top of the existing, just to get the roofing lapped into the gutter properly. That cost £££, though.

I'm not surprised roofers aren't keen to do the job or guarantee the work if done.