Should you put plastic under concrete slab?
Almost everywhere (except “California”) that slabs are placed on the ground—a plastic sheet—a vapor barrier—is located directly under the concrete slab and on top of the ground (Photograph 1). This plastic sheet is in direct contact with the concrete—as it should be in a rational world.Click to see full answer. Furthermore, do you need plastic…
Almost everywhere (except “California”) that slabs are placed on the ground—a plastic sheet—a vapor barrier—is located directly under the concrete slab and on top of the ground (Photograph 1). This plastic sheet is in direct contact with the concrete—as it should be in a rational world.Click to see full answer. Furthermore, do you need plastic under concrete slab?Thanks! Plastic is a moisture barrier generally to stop ingress from beneath the slab. If this is outdoor in an exposed area it probably doesn’t matter. I’d probably use plastic if the area is moist with little sun, just to alleviate any algae growth.Secondly, what do you put under concrete slab? Just scrape off the sod and topsoil and add gravel fill if needed. If you have clay or loam soil, you should remove enough to allow a 6- to 8-in. layer of compacted gravel under the new concrete. One may also ask, do you need a vapor barrier under a concrete slab? A concrete vapor barrier is any material that prevents moisture from entering a concrete slab. Vapor barriers are used because while fresh concrete is poured wet, it’s not supposed to stay that way. It needs to dry and then stay dry to avoid flooring problems. This is why a vapor barrier under concrete is essential.Do I need gravel under concrete slab?Whether you pour concrete for a walkway or patio, a strong gravel base is required to prevent the concrete from cracking and shifting. Excavate the soil to a depth of 8 inches, allowing 4 inches for the gravel base and 4 inches for the concrete slab.
