Prevent deck collapse with proper upkeep

Tips on eliminating dry rot and mildew, applying preservative

Q: Our 35-year-old house has a 7-foot cantilevered deck on the top floor — about 25 feet above ground level. The untreated fir joists feel solid but have large black areas on the sides — especially on the outboard end (the area closest to the house is protected by an overhang). I intend to remove the decking to repair any rot on the tops of the joists; I was told by a pest control guy to pressure-wash the black areas on the sides. I guess that is a good idea.