Before I build a wood deck...


Should I repair the original patio underneath for drainage purposes? We are new to the house and a wood deck would be perfect, but one of the slabs is raised significantly. Even gashed my toe on it! Have gone back and forth about raising it, replacing it, even leveling the grade with fill dirt and building over top. Any thoughts? Thanks!

  11 answers
  • Mogie Mogie on Jun 03, 2020

    Unless the ground you build the deck on is level how would you get the deck level? Some people slope the deck so the water doesn't pool up but the space between boards would take care of any standing water.

    A huge bonus of building a freestanding grade-level deck is that a building permit isn’t required as long as the deck’s area is 200 square feet or less (see 2015 IRC, R105.2, Work exempt from permit, #10: Decks not exceeding 200 square feet in area, that are not more than 30 inches above grade at any point, are not attached to a dwelling, do not serve the exit door required by Section R311.4). So, provided your code jurisdiction has not amended out this code section, you save time and cost by not having to apply for a permit or wait for inspections. You can build decks sized 10 feet by 20 feet, 12 feet by 16 feet, or 14 feet square without a permit, and—theoretically—if you need a larger deck, you could build adjacent deck frames that each are 200 square feet or less and don’t lap continuous decking over them, without a permit.

    When you are prepping the area back fill with gravel which will not only level the deck but provide drainage too.

  • on Jun 03, 2020

    Will the patio be visible under the new deck?

  • Rymea Rymea on Jun 03, 2020

    As long as the slab isn't in the way of the deck supports and if the slab doesn't slope toward the foundation I see no reason to do anything to it. If the deck will be high and seeing the slab underneath bothers you then you could use lattice to hide it. If you plan to store anything under the deck the concrete surface might be of benefit.

  • Ken Erickson Ken Erickson on Jun 03, 2020

    Is your new deck supported by the patio? If so, I'd recommend taking care of the patio first. The deck needs a proper foundation support.

  • Is the plan to put the new deck directly on the old patio? If so, your best bet is to remove the old patio. There's a reason it's not level and it will ruin your deck. Or, build the deck larger than the patio and above it so the two are not related.

  • William William on Jun 03, 2020

    If the slab is not tilting towards the house then you can build a deck on top of it. It will take some leveling with with concrete blocks

  • I would probably fix it, just because if you don't you'll worry about not doing it (or at least I know I would). BUT, it sounds like it would probably be ok if you did just cover over it.

  • Deb K Deb K on Jun 03, 2020

    Hi Brian, I think you want to ensure the patio is sloped away from the house, and from there you can build over it if you are putting a raised deck up, but consider using under the raised deck as storage for spare decking, you may want to level it out for peace of mind

  • Johnavallance82 Johnavallance82 on Jun 04, 2020

    Hello Brian,

    Try to fix first, before laying out money to cover it. If it is something you can't do, get a price or two from a carpenter. He may even give you a price for fixing new too........Best wishes.

  • Cynthia H Cynthia H on Jun 07, 2020

    Hi! It never hurts to investigate repairing a surface before you cover it up. Slabs can be leveled. I would get a concrete mason in for opinion and pricing. If they insist on only replacing, get a second opinion. Once you have your options, you will have the answer. Good luck and stay safe!

  • You should make sure the foundation is level before you start. That will prevent a lot of problems that could arise later.

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