Suppose the wall
on the side of the tub gives way when he removes the tub? *That will be
his obligation to fix

Not sure what you really mean here. If the wall of your place falls
apart (note language "the wall gives way" not "he breaks the wall")
what do you mean it is his "obligation" to fix it? Do you mean he has
to pay for your bad property? Within the scope of the contract that
was not about fixing your bad property? What if the porch falls off
when he's walking to the job site, is it his obligation to fix that as
well? What if your wall gives way and injures his crew? Or do you just
mean that the final deliverable must be something that actually looks
done and you're willing to pay for it as circumstances arise?