Basement Slab: How to Floor a Basement

Phase 1: Slabs

When creating a basement floor slab there are certain requirements that need to be met and there are steps that need to be followed in order. When we were preparing our plans for the slabs, we also made sure to ventilate the basement since this allows moisture (that is created when curing the concrete) to escape.

Concrete is typically used for basement floor slabs and should be put in after the roof construction is done, the basement floor drain is in place, water and sewer lines are installed and the building is enclosed. The slab should be sloped towards the floor drain and made to be at least 3 in. (75 mm) thick.

how to floor a basement

We built our own home and constructed the basement slab, we first installed the sewer lines. Next, we placed about 4 in. (100 mm) of gravel or crushed rock under slab to prevent moisture from getting to the slab from the ground. Using a sheet of polyethylene sheet, create a layer 6 mil (0.15 mm) below the slab to damproof the floor.

At times, there can be slight movement of the slab due to shrinkage during the drying process. You can use a premoulded joint filler to correct for this. Once the slab concrete is in place, you need to check for proper elevation. Curing should happen for at least 5 days at air temperature 70°F (21°C). Slabs on the ground are prepared almost the same way as basement slabs.