Frequently Asked Questions

Is Proofex Dimple installed with the dimples facing the wall (inward toward the structure) or facing outward toward the backfill and how is it fixed in place before backfilling?

Proofex Dimple is installed with the dimple projections facing inward toward the wall or structure — meaning the smooth HDPE face of the membrane faces outward toward the backfill. This orientation is correct for two important reasons: the dimple projections, when facing the wall, create the drainage cavity (the air gap between the dimple tips and the wall or primary waterproofing surface) through which water can flow downward to the perimeter drain; and the smooth outer face reduces the frictional resistance between the backfill soil and the protection membrane, reducing earth pressure transmitted to the wall and minimising the risk of the backfill dragging the membrane downward as it settles over time. Installation is straightforward: unroll Proofex Dimple along the prepared wall face (the primary waterproofing membrane must be complete, fully cured, and inspected before Proofex Dimple is installed); fix the top edge of the Proofex Dimple sheet to the wall using mechanical fixings (HDPE plugs, concrete nails, or plastic disc fixings) through the sheet into the substrate — the top edge fixings hold the sheet in position during backfilling; where two rolls of Proofex Dimple meet at a vertical overlap joint, overlap the sheets by at least one dimple row (minimum 100 to 150 mm) to maintain continuity of the protection and drainage layer; at the base of the wall, the Proofex Dimple sheet is turned out horizontally on the concrete blinding slab and directed to overlap the perimeter drainage pipe and granular drainage layer — this ensures that water draining down through the dimple cavity is directed into the perimeter drainage system rather than accumulating at the base of the wall; backfilling can proceed progressively after the Proofex Dimple has been fixed and inspected.

Can Proofex Dimple be used as the sole waterproofing system for a basement or is it only a drainage and protection accessory requiring a separate primary waterproof membrane beneath it?

Proofex Dimple is a drainage and protection accessory, not a waterproofing membrane, and cannot be used as the sole waterproofing system for a basement or any other below-grade structure that requires genuine waterproofing. The HDPE dimple sheet has numerous gaps, seams, fixings, and overlaps through which water can and does pass freely — it is designed to allow water through (into the dimple drainage cavity) rather than to prevent water penetration. Using Proofex Dimple alone as a basement waterproofing system (without a primary waterproof membrane) would allow groundwater and rainwater infiltration through the dimple sheet and into the drainage cavity — the drainage cavity would fill with water and, without drainage at the base, the water would accumulate and eventually overflow into the basement. The correct below-grade waterproofing system in which Proofex Dimple plays its role is: primary waterproofing layer — the basement retaining wall is waterproofed by a true waterproofing membrane (Proofex 30 bituminous membrane, Nitoproof 400 polymer-modified bituminous coating, or a sheet membrane) applied to the structure; protection and drainage layer — Proofex Dimple is applied over the completed, fully cured primary waterproofing membrane, serving as the protection board (preventing backfill damage) and drainage layer (channelling water to the perimeter drain); perimeter drain — a granular drainage layer (single-size gravel wrapped in filter geotextile) with a perforated perimeter drainage pipe at the base of the structure collects the water from the Proofex Dimple drainage cavity and directs it to a sump or storm drainage outlet. The three-layer system (waterproofing membrane plus dimple drainage plus granular perimeter drain) is the industry-standard below-grade protection system that ensures long-term basement dryness even in high-groundwater-table conditions.

How does Proofex Dimple help reduce the hydrostatic pressure on a basement waterproofing membrane and is it effective for basements with a high groundwater table?

Proofex Dimple reduces the hydrostatic pressure on the primary waterproofing membrane through the drainage cavity function of the dimple pattern — by creating a continuous air-gap drainage pathway between the primary membrane and the backfill soil, the Proofex Dimple allows water that infiltrates the backfill zone to drain downward through the dimple cavity to the perimeter drainage system before it can accumulate and build up as standing water bearing against the primary membrane under hydrostatic pressure. The hydrostatic pressure reduction mechanism works as follows: without Proofex Dimple (and without drainage), rainwater that infiltrates the compacted backfill soil becomes entrapped in the low-permeability backfill against the wall, building up as a column of standing water bearing against the primary waterproofing membrane with a pressure of 10 kPa per metre of water depth (1 metre of water head equals 10 kPa or 0.1 bar pressure); with Proofex Dimple, the infiltrating water drains down through the dimple cavity (which remains open because the smooth HDPE outer face contacts the compacted backfill but the inward-facing dimple projections maintain the open drainage channel) to the perimeter drain at the base; if the perimeter drain capacity is adequate, the water head in the drainage cavity remains at or near zero — no hydrostatic pressure builds up on the primary membrane. For basements with a permanently high groundwater table (the water table is above the basement floor level for significant portions of the year, as occurs in many locations across Delhi NCR, Noida, and the Ganga plain in the monsoon season and post-monsoon period), the Proofex Dimple drainage approach alone is not sufficient — the persistent groundwater creates continuous positive hydrostatic pressure that the drainage cavity cannot fully relieve, and the primary waterproofing membrane must be designed for the full groundwater head pressure. In high water table conditions, the combined system specification is: a fully waterproof primary membrane (rated for the expected hydrostatic head), plus Proofex Dimple protection board, plus perimeter drain, plus a sump and pump system to maintain the groundwater level below the basement floor by active pumping — the dimple drainage membrane still performs its protection and short-term drainage relief function, but the primary membrane carries the full waterproofing responsibility.

Related waterproofing products

Other waterproofing systems we supply & apply across Delhi NCR and pan-India.

FosrocFosroc Brushbond FLXIIIFosrocBrushbond TGPFosrocFosroc Brushbond UltraflexFosrocFosroc CementiteFosrocFosroc CemsealFosrocConplast Crystalline

Explore the full Waterproofing range & how to chooseAll Waterproofing products →Waterproofing Systems Guide →