Picket and composite stair parts should be seasonally cleaned and frequently waterproofed to avoid rot and damage. The upper surfaces of stringers can be protected with self-adhesive joist tape or other water-proof resources. Appropriate installation and servicing of gutters and downspouts also are important in controlling drinking water runoff. https://freeurldirectory.com/listings13187298/what-does-patio-deck-waterproofing-mean