The concrete patio was poured so it buts up against my elevated
concrete slab foundation with nothing in between.

Whoops there it is. If you pulled a permit, get the building inspector
out there.
Now contact an attorney. 20 years of concrete work and one of the top
ten
rules is expansion joints. I don't know what kind of foundation you
have, but
pouring an exterior slab directly against it will eventually cause
damage.
It is now cheaper for the builder to replace the slab then the house.
Lou