A common area to find water damaged flooring, underlayment and subfloor is next to a sliding glass door. This is an easy area for water to enter, especially with frequent opening and closing of the door for pets during wet weather. Vinyl floor coverings can peel up and caulking is often missing at the junction with the door allowing water to penetrate to the underlayment and subfloor. This water penetration can occur over a long period of time and lead to rot in the subfloor that is hidden from plain view.
These pictures are from an inspection where the current owner had removed the floor covering and underlayment in preparation for new flooring. The close up pictures show the hidden rot area of the subfloor next to the sliding door. The last picture shows a view of the same area from the crawlspace. The damaged area of subfloor needs to be replaced prior to any new flooring being installed in this room.
Brian Jovag, owner of Jovag Home Inspection.