How to Build a Deck Over a Concrete Patio
Introduction
Has your concrete patio seen better days? Is it cratered, stained, cracked and sunken? The patio we used for this how-to was in just as rough shape. It was the ultimate bad patio: severely cratered and cracked concrete, some areas raised by frost, others sunken after 50 years of settling. Originally, it was tiled, then the tile was chiseled off, and the pockmarked surface got a coat of paint. Luckily, we've got some great outdoor flooring ideas over concrete, starting with building a deck!
A slab with this much damage can't be fixed. But it can be covered up — and here, I'll show you how. Read on for expert tips on building a deck over concrete from two industry pros, Paul Ricalde from Paul's Toolbox and Sean Collinsgru from Premier Outdoor Living.
What Are Wood Sleepers?
Sleepers are pressure-treated 2x4s used instead of traditional joists when building a deck over concrete. They slightly elevate the deck to allow water to run off the concrete and not get trapped and rot the decking. "[Sleepers] are essential if building over a concrete slab," Collinsgru says.
For this deck build, sleepers are attached directly to the concrete slab, then decking boards are screwed to the sleepers.
Will It Work on Your Patio?
Even if your patio is in terrible shape, you can deck over it. Cracks, craters and seasonal movement along cracks are no problem. "I've built all sorts of decks over concrete that has seen better days," Ricalde says. But beware of these three situations:
- If an area is badly cracked and sinks noticeably year after year, any decking you put over it will also sink and develop a low spot. In most cases, settling concrete stops sinking eventually, so delay this project until it does.
- This project raises the level of your patio by 2-1/2 to 3-1/2 inches, so any door thresholds adjoining the patio must be at least that far above the concrete. If not, this project won't work for you. If you live in a climate where the ground freezes, allow an extra 1/2-inch so that seasonal "frost heave" can raise the slab without damaging the threshold.
- Stairs connected to the patio can complicate this project. To keep step heights equal, you'll have to raise the treads by the same distance you raise the patio (2-1/2-to 3-1/2-inches). On concrete steps, that's a straightforward job: You can treat them just like the patio, screwing sleepers to the treads and risers and decking over them.
Pros and Cons of Building a Deck Over Concrete
Consider these pros and cons carefully to decide if this project is for you.
Pros
Putting a deck over concrete eliminates the cost and labor of removing the concrete. "Disposing of large amounts of concrete can bring on a host of issues, like cost and physical labor," Collinsgru says. "Concrete isn't light!"
With this project, the results look just like a deck, but getting them is much easier and less expensive than building a deck from scratch. In most cases, it's also less expensive than a new patio installed by a contractor. The simpler you can make your deck plan, the faster and cheaper it will be to build.
You could probably replace your patio yourself for less than the cost of this project, but DIY demolition and concrete pours are big, backbreaking jobs.
Cons
"The biggest challenge is the added height," Ricalde says, "especially if the patio comes straight off the house." Clearing thresholds and doorways, and connecting seamlessly to pathways and stairs can be difficult.
Collinsgru points out problems with building on improperly pitched concrete. "If the concrete was not properly pitched, it can cause issues such as water in the basement or pooling," he says. Any existing water problems need to be corrected before building. Caulk the gap between the house and patio and fill any low spots with self-leveling compound.
When to Call a Pro
If you are unsure if your concrete patio is a good candidate for this project, consult with a pro. Also, this is an intermediate-level project, so if you are not comfortable with the skill level required, you may want to hire a pro for this job.
Before You Begin
Safety Precautions
Wear safety glasses, dust mask and hearing protection when drilling concrete and operating saws. Follow all safety guidelines when operating power tools.
Drill bits can get very hot when drilling concrete, so avoid contact with skin until they have cooled.
Tool Specifications
Aside from standard carpentry tools, you'll need a hammer drill for this project. You can get a hammer drill for less than $60 that will do the job. But consider spending $100 or more. "A good hammer drill
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