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Think about what is underneath

Waterproof deck membranes & under-deck drainage

Keeping the area below a deck dry requires its own plan. A walkable membrane, a coating assembly and an under-deck drainage system solve different problems. Start by stating whether there is a patio, storage or occupied space below.

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01

Walkable sheet-vinyl membranes

Purpose-made sheet-vinyl systems can combine a walking surface with waterproofing over a suitable substrate. Their installation includes seams, transitions and penetrations. Follow the complete system documentation and use an appropriately qualified installer.

02

Coatings and other specialty surfaces

Liquid-applied or fiberglass-reinforced systems need a compatible substrate and detailed specification. A decorative coating is not automatically a roof membrane or a repair for deteriorated framing. Ask for the system’s intended use and maintenance information.

03

Drainage below open deck boards

Water collection beneath a deck can improve a covered patio, but it is different from a roof over living space. Coordinate drainage outlets, cleaning access and the manufacturer’s installation details before enclosing the underside.

Questions worth asking

Does waterproof decking mean PVC boards?

Not necessarily. PVC planks have open joints; sheet-vinyl membranes are continuous waterproofing systems.

Can I put a roof deck above a room?

It requires an assembly designed for that use, with structural and waterproofing design appropriate to the building.

Go to the source

Official resources and manufacturer guidance used for this guide. Confirm current requirements for your project and exact product.

Duradek vinyl membrane overviewDuradek waterproofing system

Your next chapter outside

Start with a good plan.

Tell us about your space, what you want to change, and the way you want to live outside.

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