While a concrete stop can be quite an obstacle when trying to build a deck, it is not impossible to do so. A massive concrete stoop would sometime need to be removed with the use of power tools or just a plain old jackhammer but nevertheless it will be difficult as concrete as we know it has a lot of compressive strength meaning breaking it isn't easy, moreover, you need to haul the debris away later when you're done, adding to the huge laundry list of tasks to do.
If your project includes any steps that might or might not lead up into the structure of a house or to a platform or a landing that might not be covered with composite decking then you should probably stop reading now. This finished step will have to be almost 3 inches higher than it was before you started. This will create a very severe building code violation as well as a life safety hazard. The building code normally states that the risers above and below a step must not vary by more than a fraction of an inch. Although this deck installation is a little technical and time consuming but it can still be accomplished with some dedication
How to Build a Deck over a Concrete Patio
Time and Cost
The time it takes to put composite decking over your concrete front porch will depend entirely on the size of the area. A smaller project can be completed in a weekend but a larger project might take several weeks or even a month. This is also directly dependent on your skill level and how much help you can have. Apart from the size of the area that you will be working on, the amount of time also depends on how much shimming is necessary for sleepers to form a level surface, the time consuming process of installing the sleepers and the installation of the actual decking, which takes plenty of time to do correctly.
The average price range to have decking installed on concrete is around 30 to 50 dollars per square foot, depending on the composite choice, specific site factors and the design that you are going for. If you do all the labor yourself you can cut the cost in half although keep in mind that it is very demanding and skillful work, Almost 2/3rds of the project cost comes from non decking materials and labor costs.
Leveling and Layout
A weathered Patio surface will need to be fixed first and foremost before laying any of your sleepers. Install a thin overlay of concrete on any low spots or uneven areas to solve this problem. You also have the option of giving the overlay a very slight slope allowing the water to directly just run away from your house.
Once your space is prepared you can start to plan the layout. One of the most important things in your layout is that the location of your sleepers should be included in the layout and how each surface element will be existing in relation to each other. Optionally, you can also use strips of 1 inch wide painters tape to create a visual layout of your sleepers to help guide your installation.
Placing and Installing Sleepers
Sleepers are slender 1.5 inch wide pieces of ground contact rated treated lumber. You can use 2x2s, but you also might have to rip 2 by 4s if the quality of the 2 by 2 s is poor.
Sleepers can be placed directly on top of the concrete or they can even be set apart with ½” PVC spacers, Sleepers can also be completely leveled or sloped as long as their surface forms a single flat plane. Starting for the highest point in your Patio, place your first sleeper in position, using plastic shims to raise low spots if necessary.
Use a hammer drill to pre-drill into the spacers, sleepers and the concrete. Secure with concrete screws, penetrating no less than 1” into the concrete. Place additional sleepers in the same manner, using a straight edge to ensure each edge lies consistent with the last one. Use a joist deck tape to cover the top side of each sleeper.
Installing the Decking on the Concrete Slab
The process of installing decking on sleepers is nearly identical to building them on a regular deck. It is important to follow the manufacturer instructions for installing the decking. In general, starting from the outside of the deck and moving inwards, Screwing accent boards into place first.
Installing Decking over Concrete Steps
Again, it is very important to know that you cannot install decking over concrete steps if the top riser height is not more than a fraction of an inch in difference from the other risers in the completed set of stairs.
The first step to building over a stoop of concrete is to install a ledger board on both sides of the stoop. This will essentially create a box frame around the stoop by installing double joists on either side of the stoop and placing a double header beam in front of the stoop in between the double joists.
You can fill in all the area above the stoop by installing ledger boards with joists running out of the header. The 2x6 Joists should not come in contact with the concrete stoop. You may need to rip down the joists to provide clearance for frost heaving.
FAQs
Can I install composite decking directly on a concrete patio?
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Yes, but not directly. You need a sleeper or pedestal system that creates clearance for drainage and airflow; boards should not sit flat on concrete.
How tall do sleepers need to be?
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Most brands call for minimum 1½ in (38 mm) sleeper height in low-airflow situations (on-grade, over concrete/roofs). Trex allows 1½ in but recommends 3½ in (89 mm) where debris accumulates so you can clean underneath.
What’s the correct way to fasten sleepers to concrete?
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Pre-drill and use concrete screws (e.g., Tapcon®) with ≥1 in (25 mm) embedment into the slab; align sleepers with a straightedge and keep them level with shims. (Powder-actuated fasteners are also used—follow local rules.)
Do I need a specific slope for drainage?
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Yes—ensure positive drainage away from the house. A common slab standard is ¼ in per foot (2%); some deck install guides suggest ½ in per 8 ft. Keep water moving off the surface.
Should I add joist/sleeper tape on top of sleepers?
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Highly recommended. After anchoring sleepers, apply deck-joist tape on their tops to shed water and seal fastener penetrations before laying boards.
Can I glue composite boards straight to concrete?
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No. Composite decking is non-structural and needs framing/sleepers for support and ventilation. Do not bond boards directly to concrete.
How does adding decking over a stoop affect stair code?
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Risers must be uniform; the max variation is ⅜ in (9.5 mm) within a flight. Adding a deck layer changes riser heights—rework stairs if you can’t keep them within that tolerance.
What if the slab is uneven or cracked?
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Shim sleepers to a flat plane or switch to adjustable deck pedestals that create a level frame over imperfect slabs (and even compensate for slope).
Which board fasteners should I use?
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Use your brand’s specified hidden fasteners or screws and follow their gapping rules; many guides have special notes for sleeper systems (fastener length, orientation).
Any ventilation/clearance rules I shouldn’t miss?
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Yes: manufacturers warn not to install where airflow can’t be achieved. Provide space beneath the deck (see sleeper heights above) so moisture can escape and warranties stay intact.l
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