Install Vertical Bentonite Sheets: Wall-Only QA Checklist

The checklist

Pre-Installation Verification

1. 1Confirm wall substrate is sound, clean, and even; grind protrusions >5 mm and fill voids >10 mm with non-shrink repair mortar. Acceptance: dust-free, no standing water, no sharp edges. Evidence: photos with scale, inspector sign-off.
2. 2Check plumb and datum lines for panel alignment using a 2 m level; tolerance ±5 mm per 2 m. Mark start/stop heights and corners. Evidence: level reading photos and marked layout sketch.
3. 3Verify bentonite sheets type, manufacturer, and lot numbers match submittals; store rolls dry, ≥150 mm off ground, covered. Acceptance: intact packaging, labels readable. Evidence: delivery dockets, label photos, storage photos.
4. 4Confirm ambient and substrate conditions: temperature −5 to 40 °C; no precipitation onto substrate; wind controls in place. Evidence: weather log, site photos, supervisor confirmation.
5. 5Plan vertical layout from highest point downward in shingle fashion. Pre-mark penetrations and corners. Acceptance: sequence drawing or photo-markup approved. Evidence: annotated photos and supervisor approval.

Sheet Overlaps and Sequencing

1. 6Install vertical side laps ≥100 mm; clean lap zones; stagger adjacent vertical joints ≥300 mm. Consolidate with a hand roller. Acceptance: no gaps or contaminates. Evidence: tape-measured photos and roller pass photos.
2. 7At course ends, form horizontal shingle laps ≥150 mm with upper sheet over lower; apply bentonite granules or paste along the lap. Acceptance: continuous bead/granule line. Evidence: close-up photos with ruler.
3. 8Treat inside and outside corners by wrapping or using preformed corners with ≥200 mm overlap each face; fix at 200 mm centres. Seal folds with bentonite paste. Evidence: corner sequence photos and spacing check.
4. 9Eliminate fish-mouths or blisters >5 mm height by lifting, re-rolling, and adding paste. Patch tears with an oversheet extending ≥200 mm beyond damage. Evidence: before/after photos with scale.
5. 10Top termination: maintain ≥300 mm upstand above finished grade; install continuous termination bar at 200 mm centres with sealant bead. Acceptance: unbroken bead and uniform fastener spacing. Evidence: close-ups and elevation photos.

Mechanical Fixings

1. 11Fix sheets with stainless or hot-dip galvanized washers (38–50 mm dia) at 300 mm vertical centres and 200 mm at laps; edge distance ≥50 mm. Evidence: spacing measurements and photo log.
2. 12Perform pull-out checks on 5% of fasteners (min 5 per elevation) to achieve ≥0.6 kN. Use a calibrated pull-tester. Acceptance: readings ≥0.6 kN. Evidence: gauge photos, calibration certificate.
3. 13Install termination bars with M6 anchors at 300 mm centres; torque fasteners to 6–8 N·m using a torque wrench. Acceptance: torque within range; no over-crushing. Evidence: torque logs and tool calibration.
4. 14Seal each fastener head and washer perimeter with bentonite mastic; ensure full coverage without voids. Evidence: close-up photos and supervisor verification.

Penetrations and Terminations

1. 15Pipe penetrations: install split boot or cone flashing; embed in bentonite paste; lap sheets ≥150 mm around pipe. Secure stainless band clamp at 5–7 N·m. Evidence: staged photos and torque record.
2. 16Small bars/anchors: pack bentonite putty tightly around penetration; oversheet patch extends ≥200 mm all around; roll firmly to bond. Evidence: before/after photos with ruler.
3. 17At construction joints with waterstops, ensure sheet overlaps onto the joint zone ≥150 mm and does not displace the waterstop. Evidence: photo of continuous waterstop and overlap.
4. 18At dissimilar substrates (e.g., steel), prime with manufacturer-approved primer; use compatible termination strip at 200 mm centres; seal edges with paste. Evidence: primer data sheet, application photos.
5. 19Base of wall: secure sheet to the vertical face of kicker/curb; maintain ≥150 mm wrap onto vertical surface; seal with paste and fixings. Evidence: close-ups and alignment photo.

Protection and Handover

1. 20Install protective boards (e.g., HDPE dimple or cement board) over sheets before backfill; no gaps >5 mm; temporary fixings secure. Evidence: coverage photos and gap checks.
2. 21Backfill with rounded granular material; drop height <1.0 m; compact in ≤300 mm lifts per approved project specifications and authority requirements. Keep equipment ≥0.6 m from wall. Evidence: lift photos and compaction records.
3. 22Limit UV exposure: cover or protect sheets within 30 days of installation. Evidence: installation and cover dates, photos, supervisor sign-off.
4. 23Final walkdown every 10 m: mark damage, repair with ≥200 mm patches, re-photograph, and update as-built. Evidence: punch list, repair photos, signatures.
5. 24Compile handover pack: approved submittals, labels/lot numbers, calibration certs, test logs, annotated elevations, and completed checklist export. Evidence: PDF/Excel export with QR code.

Preview the printable checklist

Preview page one below. Open the image or download the PDF for all pages.

At a glance

• Deliver consistent, verifiable vertical waterproofing by standardizing side laps, course laps, corner wraps, fixing patterns, and penetration treatments. Acceptance cues include specific lap widths, fastener spacing, torque ranges, clamp forces, and patch dimensions, with photo evidence and measurements that prevent ambiguous field decisions and reduce rework after concrete curing or backfill.
• Align teams on what good looks like using SI-based tolerances and practical jobsite tools (rollers, torque wrenches, clamp bands, gauges). Built-in prompts capture lot numbers, labels, calibration data, and as-built sketches, creating traceable records suitable for handover, warranty, and future maintenance without revisiting closed excavations.
• Interactive online checklist with tick, comment, and export features secured by QR code.
• Accelerate inspections with clear groupings: pre-installation verification, overlaps and sequencing, mechanical fixings, penetrations and terminations, and protection and handover. Each step specifies method and evidence, enabling faster approvals, fewer punch-list items, and confident sign-off per approved project specifications and authority requirements.

How to Use This Checklist

1. Preparation: gather bentonite sheets, paste/granules, rollers, washers, termination bars, torque wrench, pull-tester, clamps, protection boards, PPE, and calibrated measuring tools. Confirm drawings, elevations, and approved submittals.
2. Open the interactive checklist on your device, select project, elevation, and date, and assign responsible roles for installation and inspection.
3. Work through items in sequence. Tick each step, attach photos with rulers, enter measurements (mm, kN, N·m), and record lot numbers and weather.
4. Use comments to flag issues, tag teammates, and note corrective actions. Link manufacturer data sheets and calibration certificates.
5. On completion, export the record as PDF/Excel, embedding photos and measurements. The export includes a QR code for verification.
6. Sign-Off: capture digital signatures from installer, inspector, and supervisor. Confirm all defects closed and evidence attached.
7. Archive the checklist in the project repository and share the QR-coded export with stakeholders for traceable handover.

Overlaps, Sequencing, and Corners for Watertight Continuity

Correct lap geometry is the backbone of vertical bentonite waterproofing. Maintain side laps at a minimum 100 mm and horizontal course laps at 150 mm with the upper sheet shingled over the lower to shed water. Clean lap zones and use bentonite granules or paste along overlaps before consolidating with a hand roller; this prevents capillary tracking. Stagger vertical joints by at least 300 mm between adjacent courses to avoid four-way intersections. At inside and outside corners, wrap or use preformed corners with 200 mm coverage each face, fixing at 200 mm centres and sealing creases. Eliminate fish-mouths or blisters exceeding 5 mm by lifting, adding paste, and re-rolling; patch any tears with a panel extending 200 mm beyond the damage in all directions. Keep the top termination at least 300 mm above final grade with a continuous bar and sealant bead. These tolerances deliver verifiable continuity and allow fast, photo-based acceptance during inspections.

• Side laps ≥100 mm; course laps ≥150 mm.
• Stagger vertical joints ≥300 mm between courses.
• Roll laps; no fish-mouths >5 mm.
• Corners: 200 mm coverage each face.
• Top termination upstand ≥300 mm.

Fixings That Hold Without Compromising Self-Seal

Mechanical fixings stabilize sheets until confining backfill is placed. Use stainless or hot-dip galvanized fasteners with 38–50 mm washers to spread load, installed at 300 mm centres generally and 200 mm at laps, keeping at least 50 mm from edges. Verify pull-out capacity with a calibrated tester; target at least 0.6 kN on a representative sample to confirm substrate integrity. Termination bars should be fixed at 300 mm centres and torqued to 6–8 N·m—tight enough to clamp, not crush. Seal every fastener head and perimeter with bentonite mastic to maintain self-seal around penetrations. For pipes, apply a compatible boot embedded in paste and secure a stainless clamp to 5–7 N·m; for small bars, use putty and a 200 mm oversheet patch. Acceptance cues include uniform washer bearing, no tenting, continuous sealant beads, and recorded torque and pull-test values.

• Washer diameter 38–50 mm for load spread.
• Fixing centres: 300 mm general, 200 mm at laps.
• Pull-out checks target ≥0.6 kN.
• Termination torque 6–8 N·m.
• Seal all fasteners with mastic.

Protection Before Backfill and Evidence You Can Trust

Protection boards prevent puncture and friction damage as soils are placed. Cover the membrane with HDPE dimple sheets or cementitious boards, maintaining gaps under 5 mm and secure temporary fixings to resist wind. Backfill using rounded granular material, compacted in lifts no thicker than 300 mm per approved project specifications and authority requirements; limit drop height to under 1.0 m and keep heavy equipment at least 0.6 m off the wall. Control UV exposure by covering within 30 days to protect the GCL’s bentonite. Document everything: label and lot photos, calibration certificates for pull-testers and torque wrenches, spacing measurements with a ruler in frame, and annotated elevations showing penetrations and corners. Close the loop with a final 10 m walkdown, repairing any defects using 200 mm oversheet patches and re-photographing for proof.

• Protective board coverage before backfill.
• Backfill in ≤300 mm lifts with low drop height.
• Heavy equipment ≥0.6 m from wall.
• Cover membrane within 30 days.
• Photograph labels, tests, and repairs.