Picket and composite stair components need to be seasonally cleaned and regularly waterproofed to stop rot and harm. The higher surfaces of stringers is often secured with self-adhesive joist tape or other water resistant materials. Deck flanges are generally ‘+’ formed rubbery product that slides into your parallel grooves https://wodirectory.com/listings13205070/5-simple-techniques-for-patio-deck-waterproofing