I am using some left over composite deck wood as trim in various exterior projects around the house. One of them needs some sort of sealant between the deck wood piece and the house. Does anyone have experience and can recommend a type of sealant/caulk that will adhere to this type of material? Thanks

2 Answers 2


The best exterior caulk that adheres to all surfaces, stays flexible, and is paintable with any type of paint is Polyurethane.

The only down side I found was it must be cleaned off with mineral spirits.


All common paintable and 100% silicone sealants will adhere to composite deck boards.

If you are trying to make a seal between different types of materials with different expansion properties (e.g. vinyl vs. wood vs. metal), choose a caulk that stays flexible.

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