A homeowner called.
"We just want to know one thing. Why is the floor in our kitchen bulging?"
Such a question over the phone spawns a lot of further questions. I had a lot of them. But I answered the only way I could. "I would have to see it and diagnose why." And we set up a time for an inspection.
They ushered me right to the kitchen. And to the door leading to the garage. There was vinyl flooring.
"It is easier to feel with your shoes off."
So I took off my shoes and felt around near the door. There surely was a bulge there!
And it was really, really cold! I asked if they had felt the cold area and yes they had. But they didn't realize why it was cold.
The outdoor temperature was 31F that day. Inside the garage the ambient temperature was 39F. And the floor inside the garage door was 49F. And the cool spot had a particular triangular shape, which you can see to the right.
The triangle you see was also the shape of the bulge.
Beneath this is the furnace room. But there is framing there which runs from the right side of the door, and running at an angle to the left follows just along that cold spot. The rest is not visible, or accessible from below, because of the garage foundation wall. The thermal image reveals the width and shape of that floor joist, and its right-angled companion, as slightly defined reddish lines. The rest of the flooring is warmed by the furnace room below, a comfy 70F.
The conclusion? There is no insulation inside and beneath the floor immediately inside the door, and the cavity without insulation is framed just as you see here. Repeated heating and cooling of the seasons has caused the flooring, almost certainly nailed, to release from the floor joists below. Expansion and contraction has caused the bulge. Can it be insulated now? Yes. They intend to remodel the kitchen, including a ceramic tile floor. I recommended that they wait until that point, and cut out the bulge in the floor. That will reveal the uninsulated cavity and they can insulate it at that point, and replace the floor. This should solve any future bulging as well.
My recommendation: When you know of an anomaly and cannot figure it out, try calling a home inspector! Although home inspectors are considered by some to be "placebos" and "almost never find anything," every now and then they just might have the experience or tools necessary to figure things out.