Rob Rosen is diving into a basement remodel, a job that involves digging out and removing a concrete slab to provide more headroom so the basement can be turned into usable living space.
He’ll reinforce the footing and foundation as needed, but when it comes time to build a new floor for the basement, Rosen wonders whether he can go with something other than a concrete slab.
“I would love input from someone who has put a vapor/water barrier, some foam insulation between 2×4 sleepers and then used some form of wood flooring that would work for higher humidity situations,” Rosen writes in a Q&A post at Green Building Advisor.
There’s nothing that Rosen can find in the Washington State building code that would prevent him from trying it.
“Concrete is soooo not environmentally correct if not necessary,” he writes.
Can Rosen swap wood for concrete and still get a durable, structurally sound basement floor? That’s the issue in this Q&A Spotlight.
Stopping the migration of moisture from the ground is key
Keeping ground moisture out of the basement is important, but it is the rigid foam insulation and the vapor barrier that actually do the work, not the concrete, says GBA senior editor Martin Holladay. In general, Holladay writes, the rigid foam goes down first, followed by the vapor barrier. “Above the polyethylene, the finish materials are up to you,” he says, “and and your local code inspector, of course.” [Editor’s note: As pointed out by Mark F. in Comment #5 below, a basement slab often has a structural function: It prevents the foundation walls from being forced inward by soil pressure. GBA readers should consult an engineer before omitting a basement slab.]
In terms of durability and cost, Holladay favors concrete,…