Spec a bentonite waterproofing system: where it's appropriate and key install requirements

Steps

1. Appropriate use: blindside or vertical below-grade walls, and under-slab applications, where a working exterior face for backfill exists but priming/torching isn't practical — bentonite tolerates damp substrates and cold weather better than fluid- or torch-applied sheet systems, but is not appropriate in flowing/moving groundwater (which can wash sodium bentonite out before it confines) or in saline/brackish groundwater (which inhibits swelling).
2. Substrate prep: repair honeycombing, indentations, and rock pockets with trowelable bentonite; substrate should be smooth and free of sharp protrusions that could puncture panels.
3. Install per the manufacturer's current guide spec: panels are typically fastened near the top edge only and overlapped at the edges (manufacturer literature shows figures like 1 fastener per 12 in o.c. and a 4 in minimum overlap) — confirm exact spacing against the selected product's current spec sheet, as these vary by manufacturer.
4. Protect from premature hydration: keep panels dry (temporary poly covering) until backfill is placed, since hydrating before confinement lets the clay swell without the compression it needs to seal.
5. Backfill promptly in compacted lifts with clean, compactible soil (manufacturer specs commonly call for a minimum compaction such as 85% Modified Proctor) so the bentonite hydrates under confinement rather than freely.