Let’s compare costs
Average 2500 square foot single story house:
Replace roof: $15,000 to $20,000
Average slab foundation repair: $8000 to $9000. I have seen bids as high as $80,000.
This surprises many people, but it is true. Unfortunately, every roof will eventually have to be replaced. The large majority of what is called foundation repair is optional and/or a waste of money.
Do you have $80,000 to waste?
Does replacing a roof adversely affect the foundation?
It is not unusual for some new distress for show up soon after a roof has been replaced. The culprit is not likely to be the root of the problem, at least not in the way many people imagine.
There is very little additional load added to the roof. The more likely source is the vibrations initiated by the hammering of the new shingles.
The distress is almost always cosmetic and is easily repaired without repairing the foundation.