We have an old house in the Philadelphia area which we bought last year. This has a slate roof and we were told by our home inspector that we'd need to consider replacing it in 10 years. It is the original roof and has been on the house ~70 years so I think the estimate of 10 years is conservative. I plan to continue having the roof checked out and slates replaced as necessary.
Spray foam insulation is attractive because we are installing an AC system and it'll bring this within the thermal envelope of the house, albeit at a premium cost. Assuming the lifetime is so short (and all the insulation will be out when a new roof is installed) I'd expect that I could have roof leaks or other issues before the roof is replaced.
Does this type of insulation add major overhead to what would be simpler tasks? How do leaks manifest with spray foam insulation? Do they hide themselves for a longer period?