Hello, I have a question about insulation. After removing one of the drywalls and the old linoleum in the kitchen, I found that the plywood above the diagonal sub-floor doesn't go all the way to the wall frames exposing wide, about 1/2 in. gaps in the diagonal sub-floor (on the photo). I want to insulate them to prevent air leaks, pests and dust in the kitchen from the crawl space. What is a good way to take care of these gaps? I can think of stuffing them with caulk or spray foam from the kitchen side. Or apply some insulation to the entire floor from the crawl space, which I am not sure is possible because of its limited accessibility: I could barely crawl there squeezing myself between floor joists and the ground.

Use the spray foam. This will seal the area but won't help too much with the rest of floor if not insulated.

Chuck