I have a townhouse built on a concrete slab. Laminate flooring was installed 5 years ago, and has buckled severely at the patio door.
I suspected water intrusion, cut back the laminate, and saw:
The original concrete slab stopped about 10 inches from the interior wall face.
A styrofoam surround (about 1" thick, maybe an expansion joint?) between the concrete slab and a framing member run parallel to the wall / door.
An uneven (rough) concrete surface outwards from the framing member, onto which is mounted the exterior patio door.
From the finished interior slab to the adjacent framing and rough concrete is a drop about 1/4". (Appears the interior slab has lifted about 1/4" from the original build).
It seems the laminate flooring installers 5 years ago noticed these surfaces and tried to bridge the gap with some sort of filler that simply expanded (had a hollow air bubble underneath) with moisture.
I'd like to repair this situation ASAP as I am intending on moving in shortly, but would benefit from expert advice.
Does anyone have any guidance on this?
Thank you sincerely,