So you want to put a wood deck on a cement patio? That is not such a big project. Is your cement patio in good shape? That is the important consideration. If the present patio is sound and level a lot of the work is already done for you.
At your local home improvement store you can buy pre-made concrete bell-bottom anchors that have brackets attached to them for 2” X 4” floor joists. All you have to do is set them down, line them up, and nail away.
When You Need to Extend
You might find that you want a bigger deck than what your current cement patio covers. Not a problem. You will have to install post footings using 4” X 4” posts with 2” X 4” brackets. When you dig the footings for these posts, line them up with the existing posts that you have on the cement patio.
Use at least one bag of cement per post and use a line level to make sure that you have a level with the cement patio post carriers.
Keep on Building..
Once you have the footings established, you just need to lay in your floor joists, which are 2′ X 4′ s and make sure you use pressure treated lumber or some of the newer products that are expressly for decks and outdoor applications.
Once you have the joists installed, you can start nailing down the horizontal members; what you will walk on. Do not snug them up, allow about 1/4” between each board. This will facilitate air flow and water drainage.
Once the entire deck is knocked out, there are other finishing touches that you might want to consider. How about handrails? The deck might also step up a level to make for a more dimensional architecture.
Consider putting seating boxes around the perimeter of the deck. These can either be simple bench seats or hinged ones that are storage spaces for gardening equipment.