0

I need a sealer Caulk to fill a approx. 3/8" gap between my Composite Decking boards to waterproof and prevent water from dripping between the boards and going on to a deck below. I want the rain water to flow over the composite decking boards to the edge of the deck and run off onto a roof that will take the water away.

What is the best product for this application? What product will adhere to and seal to Composite Decking?

Improve this question
3
  • 3
    I would not recommend sealing gaps between deck boards, decks are carefully designed and constructed and those gaps serve an important purpose. The best way to divert water from a deck and prevent it from falling through would be to enclose the upper deck or at least add a roof above it.
    – Fredric Shope
    Mar 23, 2021 at 15:26
  • 5
    You're asking the wrong question. Caulk is not a solution for this--it will look terrible and it will fail in short order. To provide solutions we need more information about your deck. Photos would be great.
    – isherwood
    Mar 23, 2021 at 16:13
  • You have a deck below a deck? Why not just waterproof both decks, which I imagine is mostly done for you if you're using composite decking materials?
    – TylerH
    Mar 23, 2021 at 19:20

1 Answer 1

Reset to default
4

Typically you need those gaps for expansion of the boards in hot weather- if they're tight to each other they can get damaged as they expand from heat.

They make under-deck panels that catch the water and direct it out a side that work very well. That would be a better solution than caulking, which would most likely need to be re-done every year or two anyway.

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.