回复：cost of fixing home problems

Most of your questions refer to small problems that either you can fix yourself or cost little.

The one that could be major problem is the sagging roof. If you can go to the crawling space underneath the roof then inspect the plywood decks closely. If the decks are black and soft (poke with a screwdriver) then it means that there was water damage and the wood is rotten and not strong enough to carry the weight of the roof-- the asphalt tiles are very heavy, especially if you have more than one layer. If the house is not leaking and the tiles are in good condition, you might get by for a few years with inspection and some small fixes every year. If the roof is over 10 years, you'd better get the whold thing done

The roof replacement cost is high. Budget at least $20/sq.f without plywood replacement and $23/sq. f with plywood job. For a good sized house it could be a 10K job. That's why it's important to inspect and fix each year to stretch the interval between roof replacements a few years longer. 25 year shingles don't really last that long without proper maintenance.