Deck over concrete patio

PAmbrose

I have a 6-8 inch concrete patio in my backyard that is in good shape (no cracks) but unsightly. I want to build a deck right on top of the patio. The deck won't be elevated more than a few inches over the concrete. My questions are as follows:
-First of all, are there any problems that might arise by building the deck right on top of the concrete?
-I was planning on using either 4x4's, 2x4s or a combo for the frame. Any suggestions?
-What should the spacing (length and width wise) be for the frame (How far apart should I space the 4x4's/2X4's)
-How should I secure the frame into the concrete?
-I was planning on using Trex for the decking. How far apart should the planks be spaced? I assume they shouldn't touch each other, but want them relatively close with minimal spacing.

Thanks for the help,
Paul

naehring2000

If the deck will be connected to your house you need to put footings in so the deck can't rack from frost, don't secure it to the patio as that is most certainly independent from the house, and if one or more of your footing locations fall on the concrete patio you will need to bust open the concrete to dig for a sono-tube.

meboatermike

If this deck is going to be right on the concrete patio that you say is 6-8 inches thick and in good shape, I would use pressure treated ground contact 2X sleepers right on top of the patio. I would not attach the deck to the house in case there is any patio/deck movement. If that patio is as thick as you say it is, I certainly would not bust through the patio to put in sono-tubes unless required by your local codes/code enforcement officer.

Scuba_Dave

As long as you don't attach it to the house you could build it on top of the patio
I assume you are located in PA ?
How many inches is a few inches ?
I might build a frame out of PT 2x4's & use brackets & tapcons (or something rated for concrete/outdoor use) to secure it

naehring2000

Right I wouldn't bust through the concrete for sono-tubes either as long as its a free floating structure not attached to the house, of course unless your local codes require it.

PAmbrose

I'm actually located in MA. I'm not going to attach the deck to the house. My plan is only 4 inches elevated off the patio. Is there any reason to use 4X4s over 2x4s for the frame? How far apart should I space the brackets if the frame is 20 feet long

Scuba_Dave

No reason to use 4x4's...just more contact with cement
Build a 2x4 framework for the Trex decking
Might want to do a search for "Trex " on this site 1st
People have had problems with it

Concerns with deck on patio:
Water needs to be able to run off, so existing patio has to be sloped right
Ventilation under the deck...don't want mold growing - ties into slope of patio
If this faces South the sun will dry it out pretty quickly
Anything that falls thru the deck will not be able to be retrieved very easily

Rather then decking that can rot eventually (or Trex that can fall apart)
I think i'd put in patio block

PAmbrose

Thanks a lot. I appreciate the help

Pat M

Pambrose-
Hello, I am a representative from Trex and came across your post. There would have to be a sleeper system between Trex and any solid surface such as your concrete patio. A sleeper system is a buffer between the solid surface and Trex. Drainage, access and airflow are critical. Water must be able to flow through and away from the deck.For repairs and removal of debris, joist system access is necessary. Good airflow will keep the decking dry and good-looking. Please feel free to contact me if I can be of further assistance. I can be reached at 800-BUY-TREX or question@trex.com.
Pat M-Trex Company

joetab24

are you doing this project? i am planning something similar.

Ron6519

A stone patio or paver layer would be a more permanent and need less attention then a wood deck.
Ron

pberr

Can you send me somewhere that shows step by step on how to build a deck over concrete patio with sleepers? Not fully grasping the idea. Video would be great or pics are fine too. Also, lots of concerns with lil critters under the patio...any ideas on ways I can eliminate them living under the deck. I'm trying to keep as low of a profile as possible with our deck, maybe 4". Also, the deck will be going over concrete and extending over some grass areas which I'll be using concrete supports in those areas.

joedelli

I am going to build a deck over my concrete patio. After reading many blogs I have found that a floating deck is the best choice for me. My patio is 3 concrete steps (which I will be covering with PT wood) down from my back door. My Bilco bulkhead door is 8 inches above patio level. My only option (feasibly) is to build a floating deck about level with the top of the bottom concrete step. This would put the level of the deck about 3 inches above concrete patio level. I have determined that PT 2 x6 framing , 16" on center for 5/4 x 6 PT decking, will work, supported by concrete blocks (in lieu of floating deck piers- too high for my project). This will allow water to escape and dry out. I will be using screening to keep small animals from getting under the deck. The deck, 20 x 24, will extend beyond the concrete patio by 3 ft onto grass. Here I will dig out grass/sod, lay screen and rocks (provide drainage for any water collecting under deck. The concrete patio is 30 years old and has settled a little. I don't expect further settling. The deck will have a slight pitch away from the house.
Welcome any suggestions.

Ron6519

The way you describe the construction would put enormoue weight on the concrete slab. To expect no settling is not logical.
I would recommend cutting through the concrete at various places and pouring footings below the frost line. The number and location of these footings would need to be planned out.
Ron

joedelli

Ron, I appreciate the comments. However, I should have said that the concrete patio has done its settling after 30 years. We built the patio digging down to stable gravel, compacted and re-enforced with wire and the concrete was high psi commercial grade. As far as weight disbursement, I planned on using concrete blocks for support (much like the precast deck piers) under the deck framing. I forgot to mention that I may have to secure the deck to the concrete to meet code. But it still has to be a floating deck.