We have a duplex in southwest Florida with subfloors. In December for the last 3-4 years cracks have appeared where the ceiling and walls meet at some of our interior walls but not exterior or common walls. The cracks vary in width with the largest being about 1/4 inch. One bathroom door sags so force has to be applied to close it and it will not latch. About 2-3 months later the problem corrects itself. All of this takes place during our dry season so rainfall is not an issue. Several general contractors have gotten in the crawlspace below during the problem time with a laser and said everything is level. We need resolution so it does not continue to happen.