This detail provides proper application method of an under slab mud mat. Under slab construction is completed in occupied spaces to prevent groundwater from intruding into the floor. Under slab construction can be completed through a compacted soil/gravel bed or a non-reinforced concrete slab (minimum of 2 inches). Dewatering of the site is required prior to construction of the under slab mud mat.

Materials

Waterproofing barrier: Reinforced waterproofing membrane.
Protection: Asphalt protection board or 6-mil polyethylene film.
Filter mat: Butyl sealant tape.

Execution

Under slab mud mat: Over the under slab, apply waterproofing barrier in accordance with the manufacturer’s latest printed specifications.
On sand/gravel bed: Loose lay waterproofing material over the area and tack in place with fasteners and plates.
On concrete slab: Fully adhere waterproofing barrier to the concrete surface in application rate required by the manufacturer.

Apply protection board or 6-mil polyethylene film over the completed waterproofing barrier in accordance with the manufacturers latest printed specifications.