In retrofits, when are capillary breaks under slabs feasible and how do you control moisture wicking?
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If the slab is open or replaced, put down washed gravel and a vapor barrier before pouring to stop water from coming up. For existing slabs you can’t lift, seal the surface with a coating that lets vapor through. Also, improve outside drainage and keep moisture down around the edge, so the slab stays dry.
Capillary breaks under slabs are feasible when you can excavate or install a layer between the soil and slab, typically using crushed stone or a vapor‑permeable membrane. To control moisture wicking, combine the break with a continuous vapor barrier and proper perimeter drainage, ensuring the barrier is sealed at edges and any penetrations
Capillary breaks under slabs are feasible in retrofits when the slab is in good condition, and the primary concern is moisture wicking or vapor transmission.