How to Build a Concrete Slab

Yes! It’s easy to learn how to pour concrete on your own — it’s a task suited for most skill levels. The keys to pouring concrete are to plan ahead carefully, prep well and work quickly.

It’s better not to pour concrete directly onto the dirt. Instead, use a layer of gravel underneath your concrete slab. Because concrete is porous, it absorbs water. If you place concrete directly onto dirt, water will collect under the concrete and slowly erode the bottom of the pad. Gravel prevents this erosion by allowing water to drain away from the concrete. Typical concrete forms have a 4-inch layer of gravel underneath.

In general, for residential areas like walkways and patios, 4 inches of concrete is sufficient for a slab. For a deck or deck stair landing, again, around 4 inches of concrete is sufficient.

The most important part of preparing your ground for a concrete slab is to make sure that it’s compact and well-drained — if it’s not, you risk the ground flexing, which can cause stress cracks in the concrete. Damp soil is ideal, but if there’s water pooling on top of the soil, then it’s too damp to erect your slab on.

To build a landing for deck stairs, most building codes require the pad to extend beyond the steps by about 36 inches, behind the steps by about 12 inches and on the sides of the steps about 6 inches.

Always follow building codes for installation in your area.