It is imperative when you find dry rot that you replace or repair it quickly so the fungus will not spread. If you are unsure if you have dry rot in your home you can start by checking near any wet plumbing in your basement. Check any area inside or outside your home where wood is touching the soil or exposed to weather. Since the dry rot fungus usually enters at the end grain or base of a foundation post, if possible check this and the area where the window frames butt against the sill, as well as other such areas. When you reach the windward side of your house pay special attention.
Wind tends to force rainwater deep into any joint or crack.
If you see flaking paint or a discoloration in the paint you are seeing the first symptoms of dry rot. If you find structural damage due to dry rot you will need to call a professional. Windowsills, doorframes, porch rails and siding are areas you might be able to fix yourself. To being you will need to cut away the affected area plus six inches on either side. Then you can splice in fresh wood.