Property in question 50's terrace with the dreaded fin lock gutters. We've been asked to price up to reline them with EPDM.

My head says not worth the effort I also know the ideal solution would be to remove them completely, extend the rafters and use modern fascias / soffits.

We have to put in a price anyway as we do a lot of work for this authority but I can't see EPDM working long term.

Thoughts or any coatable solutions?

I own a property which has these gutters. The only cost effective solution I found which has worked is using continuous aluminium extruded gutters formed with a special profile to fit as a liner to the concrete finlock. One of the main problems with the finlock gutters (apart from the leaking), is the thermal bridge they cause. However simply cutting the off from the outside is still not sufficient. You would need to cut the back to the outside face of the inner leaf of the wall (as long as the rafters and wall plate do not hinder things too much), then extend the rafters out, and put new sofits, fascias and gutters on. Lining is certainly more cost effective.