Properly repairing dry rot damage is a job for trained and experienced professionals. It requires the elimination of conditions that allowed moisture into the area that caused the problem. This means opening up the area of rot sufficiently to expose the entire area of rot and beyond.
Dry rot, caused by moisture-triggered fungus, can undermine the structural stability of any building.
Signs of dry are typically found around window sills and door sills where moisture can collect. Signs of dry rot include soft wood, cracked or peeling paint, and blistering. If you think you have dry rot, poke the area with a screwdriver. If it goes in easily or feels spongy, you probably have dry rot.