Concrete-free Slab

Prompt

Can we build a floor on grade without concrete?

Findings

Any opportunity to reduce concrete can result in construction with fewer logistical hurdles and a smaller carbon footprint. Design / builder Josh Salinger demonstrates his approach to a concrete-free slab on grade here. First, he places a minimum of 4" drain rock to act as a capillary break between any groundwater and the slab. Then, he can insulate and lay an air and vapor barrier to completely protect the plywood subfloor from moisture. An alternative strategy would be to lay wood sleepers down and then frame a floor with 2x4 joists, shimming to level as required. This technique allows for batt insulation to be placed in the joist cavity, reducing the need for rigid sub-slab insulation. A primary benefit of the concrete-free slab is that it can be repaired over time, and any pipes buried below it can be accessed if needed.