It's one of the most common backyard questions in the metro's older neighborhoods: there's a concrete patio off the back door — cracked, sunken at one corner, hot as a skillet in July — and you'd rather have a deck. Do you have to jackhammer the slab out first? Usually not. In most cases the slab you're tired of becomes the foundation for the deck you want.
How it works: sleepers over slab
The standard approach is a sleeper system: pressure-treated framing members laid over the concrete on spacers, leveled to correct the slab's slope and dips, with composite decking fastened on top. The slab keeps doing what concrete does best — bearing load — while the sleepers create a drainage gap and a flat, consistent plane for the surface. Done right, water still sheds across the slab underneath and the framing stays dry and ventilated.
Where the patio sits well below the door (common on older homes with a step-down), there's a second option: a low-profile floating deck framed over and around the slab, bringing the finished surface up flush with the interior floor. That kills the awkward step, and it's one of the highest-impact upgrades an older backyard can get — the patio stops being a landing and starts being a room.
What the slab has to pass
Concrete with surface cracks, stains, or spalling is fine — cosmetics don't matter once it's covered. What we check is movement and drainage:
- Heaving or settling. Colorado's clay soils and freeze-thaw cycles move slabs. Modest, stable settling gets corrected in the sleeper heights; a slab that's actively heaving seasonally will telegraph that movement into anything built on it.
- Drainage. The slab needs to shed water away from the house, and the finished deck height has to keep proper clearance below the door and any siding.
- Height math. Slab plus sleepers plus decking has to land somewhere sensible relative to doors, steps, and yard grade. Usually it does; occasionally it dictates the low-profile framing route instead.
A slab that fails the movement test doesn't necessarily mean demolition either — decks on their own footings can simply span problem concrete, ignoring it entirely.
What it costs
Building over a sound slab is one of the rare deck scenarios that's cheaper than the standard build: the foundation already exists, so there are no footings to dig and pour. For a sleeper-system composite surface over an existing patio in the Denver metro, most 2026 projects land around $25–$40 per square foot installed — against $40–$70 for a full ground-up composite deck. Add a pergola or roof cover and that skillet-in-July slab becomes the shaded room our Littleton tongue-and-groove patio cover turned out to be.
Wondering whether pavers or fresh concrete makes more sense than decking over? Our concrete vs. pavers comparison covers that fork. Or skip straight to the real answer: send us a photo of your patio and we'll tell you what it can carry.
