I have a large concrete patio at the rear of our house - 12 inches thick, with no settlement noticed (it's been down for about 7 years now).

We're considering extending our deck out; at the moment we have a simple 5x5' deck which just leads to a set of steps down to the patio. We want to now build a 12x22' deck, and extend the roof out over the new deck.

Question; For the deck footings, do I need to cut through the patio and dig to below the frost level (~36inches in Utah), and then build back up with concrete footings, or can I just attach the 6x6" support pillars of the deck direct to the patio?

  • 2
    I Think this is a code issue, have you asked what the code for your muni is in relation to decks. The slab is thick enough but it can still be moved up and down by the ground under it. How is the roof going to supported? Certainly you will need permits so you should go to the municipality that has jurisdiction over your home and ask.
    – Alaska Man
    Commented Jul 23, 2018 at 22:22
  • In my area (not Utah), floating deck is (or at least was when I built it) permissible but with constraints, particularly on the height of the deck above the ground. How high (e.g., "steps down to the patio") is the deck? Commented Aug 26, 2018 at 20:20

1 Answer 1


If the footprint of the new deck fits over the patio, you should be fine with a freestanding floating deck. Precast post blocks like this can transition from the slab to the deck framing, and provide the all important gaps so the framing can dry out: enter image description here

Consult locally for wind tie down requirements: you'll probably need to sink some anchors into the slab, and add cable restraints to the deck framing : any sort of roof will act as a sail. Going freestanding greatly reduces headache and risk of attaching to the house.

  • 1
    I built a floating deck and it is great - and in my area actually legally done without permits within certain constraints. But there are definite limits on height and "steps down to the patio" implies some measurable amount of height above ground. Commented Aug 26, 2018 at 20:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.