Building Deck close to a concrete surface
by Doug Shannon
(Battle Ground, WA )
I would like to build a wooden deck on top of an existing concrete patio. The top of the deck will only be 8.5 inches above the concrete. How do I proceed? I don't want to have to tear up the concrete.
This is really quite simple to do. You will have to take into consideration the width of the joists and decking in order to maintain the 8.5" elevation you are looking for. However, the only thing you really should do is try and maintain perfect level across the framing which will essentially be sitting on the slab. You can fine tune the level by using some shims.
You would be wise to rest the joists on something like blocks of wood or rubber pads to keep the joists completely dry. If you do this then the structure should last a lifetime.
Lastly, if you really want the deck to never move you use some metal strapping and secure it to the concrete.