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Advice on low-level unattached deck

I recently purchased my first home and am looking to build a deck in our backyard. The backdoor opens onto a 8'x12' covered concrete patio which I'd like to extend 8' out and 12' over with a wooden deck, without removing the current concrete patio - so 1/4 of the deck would be that concrete portion. The patio and backdoor of the house are approximately 5-6 inches off the ground and the ground is fairly level. I've decided not to attach the deck since it's so low to the ground and I don't want to risk water damage by drilling into the concrete foundation. We live in San Antonio, Texas, so frost isn't a real problem. My original plan when designing the deck was to place 4x4 posts with concrete footings, attach 2x4 boards to serve as joists, and then attach the planks to that. I was planning on placing posts every 2.5-3 feet since the deck would be supported by just the 2x4 joists and the posts. Is this a viable option? Everything I've been reading on-line talks about using beams attached to the posts which then attach to joists which then attach to the planks, but with only 5-6 inches of height to work with that just doesn't seem feasible. Any suggestions? Thank you!

Re: Advice on low-level unattached deck

When I lived in an area where we had a flat yard, little chance of heaving in the winter, etc. and we wanted a low-height unattached deck (for tax purposes), we used a product called deck blocks. These are shaped like a pyramid with the top cut off. In the top, the cement blocks have an opening you could insert a 4x4 in (very wobbly) and slots to lay 2x lumber in edgewise.

So, you got the ground level, put down some ground cover and maybe some stone to hold it down, and leveled the deck blocks on it. Then, you put your deck joists, etc. right on the blocks and the slots held things in place while you attached the lumber together. For us, it worked VERY well. We hid the blocks under the deck so you never saw the rim joists. I am not sure how it would work with your patio because I suspect the grass part might settle a bit more than the patio when the weight of the deck is on it.

Good Luck!!


Re: Advice on low-level unattached deck

Thanks for the reply! I had considered the dek-blocks, but my concern was that there is 6 inches from the ground to that slot, then you have the 5.5 inches or so for a 2x6 joist/beam, then another 1.5 inches for the plank height. You end up needing a little over a foot in height for it total, and since my door is only about 6 inches off the ground i would end up needing to dig about 6 inches down for the entire deck footprint - that not only makes me uncomfortable digging so close to my foundation, its a heck of a lot of digging!

Re: Advice on low-level unattached deck

Your original plan of 4x4 posts every 2.5-3 ft and 2x4's joists/beams won't work, in my opinion, and may not be to code.
This plan calls for about 12 posts and about 5 2x4x12. Then you place the deck planks on top of the 2x4's. You may meet your height restriction, but this plan won't fly.

A better way to do it with your height restriction:
1. 4x4 post, in 2' concrete in the ground and 1" above grade, every 1' lengthwise and widthwise. Total posts: around 96 for an 8x12 deck.
2. 2x4's joists/beams, connected to the posts with simpson connectors. Total 2x4x12: about 10. It would be better to double them.
3. 2x6x12 deck planks.
4. Your finished height:
1" post + 3.5" joist/beam + 1.5" plank = 6".
Check your local codes.

Question: why not pour concrete instead for the addition?

Re: Advice on low-level unattached deck

Thanks for the advice dj1! I considered concrete, but just prefer the look and feel of a wood deck. Your suggestion seems like it would solve the problem!

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