Above-Joist Deck Drainage: Water Stops Above the Framing
Above-joist drainage intercepts water above the deck framing. It can be a separate layer beneath the boards or, with AmeriDex, a board-and-seal assembly integrated into the decking surface.
Request free samplesHow AmeriDex manages water at the surface
Cellular PVC boards work with the Dexerdry TPE seal, installed between the boards as the deck is built. The assembly is designed to direct surface water toward the planned discharge edge.
The seal is only part of the installation. Follow the current requirements for pitch, board direction, fastening, flashing, overhang, and sealing at the specified perimeter or end details.
See the two-part system and installation overview, or read how AmeriDex compares to membranes, aluminum planks, and coatings in the waterproof decking guide.
Above-joist does not always mean surface-integrated
Separate membranes or troughs may sit above the joists, below the deck boards. Below-joist systems instead collect water underneath the framing. AmeriDex differs by combining the decking and drainage assembly at the walking surface.
For new decks and qualifying full re-decks
AmeriDex cannot be added to boards that are already fastened in place. A full re-deck may be suitable after the old boards are removed and a builder confirms that the existing framing and drainage details meet the installation requirements.
Check the re-deck requirements
Plan the project budget
The cost guide provides a material planning allowance for decking and the Dexerdry seal. Confirm fasteners, trim, freight, tax, labor, framing, and all other inclusions in a written project quote.
Frequently asked questions
What does above-joist drainage mean?
The water-management layer is above the framing. It may be a separate system below the boards or a surface-integrated assembly such as AmeriDex boards with the Dexerdry seal.
Can I use the system on existing framing?
Possibly, as part of a full re-deck. Remove the existing boards and have a qualified builder assess framing condition, pitch, spacing, flashing, and installation details before specifying the system.
Does drainage make an outdoor space weatherproof?
Deck drainage manages water from above. Wind-driven rain can enter open sides, and drainage does not replace structural inspection, maintenance, or appropriate building-envelope details.
Where can I get project-specific pricing?
Use the material cost guide for planning, then request a written quote with your deck dimensions, location, and project details.