Several commercial waterproof deck systems are available to create a dry space under a deck but rune stactic of adding a roof to a deck seems to be just as effective.
Cheapest way to waterproof under deck.
Epdm is available in widths up to about 50 so you can generally lay down a continuous sheet without any seams.
What makes the underdeck ceiling so innovative is its simple and efficient system of vinyl gutters and panels which attach underneath the deck.
The water drains straight.
The underdeck ceiling system can turn the ugly space under your deck into an outdoor haven that s dry bright clean and enjoyable without costly reconstruction.
How to dry in underneath a deck without the expensive underlayment or systems.
There are underdeck cielings systems that are available but i think the most inexpensive way would be to hang corrugated plastic or metal panels from the rafters.
This membrane prevents water from reaching the areas below the deck such as a roof or open area.
For pricing and availability.
26 in x 120 in deckdrain opaque tan under deck ceiling panel.
This is used to provide a durable long lasting waterproof membrane on top of your existing deck.
One method of waterproofing under the deck is to install a membrane.
Trex 12 5 in x 10 75 in x 17 5 in brown plastic deck.
And it s inexpensive and easy to build using materials found at any home center.
First you need to purchase a continuous sheet of epdm which will cover the entire deck area.
A perimeter frame and graduated spacer nailers are fastened beneath the deck joists so that the plane of the ceiling slopes slightly at least 1 4 inch per foot away from the house toward the joist header.
To install this system under an existing deck cut the membrane pieces with a shallower droop no more than 4 inches and staple the membrane to the underside of the joists caulking each seam as described in the following pages.
Designed for contractors and diyers who want an affordable attractive and easy to install vinyl deck flooring product econodek waterproof vinyl decking is more than a deck flooring product it s also peace of mind.
For pricing and availability.
Screw 2x2s to the joists over the membrane as in the drawing below.
Here are the details in case you d like to build your own building a deck with a roof version.