A new roof means stripping the old covering right back and rebuilding from the timbers up, rather than patching what's already failing. We take off the old tiles or slates, check the rafters and battens underneath, then fit a breathable membrane, new treated battens and your chosen tile or slate. Flashings, valleys and abutments are done in lead, and ridge tiles are dry-fixed where it suits the roof so they don't work loose in the wind. Done properly, it's a job that sets you up for the next few decades.