Below-Grade Waterproofing
Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
Showing changes from Rev 5
to Rev 6
in Below-Grade Waterproofing.
---
title: Below-Grade Waterproofing
…163 unchanged lines
## Even a "seasonally high" water table — groundwater that rises only during spring thaw or prolonged rain — is a hydrostatic condition during those periods. {note}
+## IBC Section 1805 requires that where a subsurface soil investigation indicates a hydrostatic pressure condition exists, walls shall be waterproofed with a system capable of resisting hydrostatic pressure.
+
+## Where hydrostatic pressure will not occur as determined by IBC Section 1803.5.4, dampproofing is the minimum requirement.
+
+## The design basis shall be explicitly documented in the contract documents so that the membrane type selection is traceable to a geotechnical basis.
+
```datasheet
label: Design Groundwater Condition
…7 unchanged lines
```
+## An assembly sized only for non-hydrostatic conditions will fail under seasonal hydrostatic loading. {note}
+
+## The geotechnical engineer's report shall establish both the normal groundwater elevation and the expected seasonal high water table elevation.
+
```datasheet
label: Design Groundwater Elevation
…9 unchanged lines
```
+## Where the design groundwater condition is intermittently or continuously hydrostatic, the waterproofing membrane shall be capable of resisting the design hydrostatic head confirmed by the geotechnical investigation.
+
+## IBC Section 1805.3 requires that waterproofing be applied from the bottom of the wall or slab to not less than 12 in. above the maximum elevation of the design groundwater table.
+
```datasheet
label: Waterproofing Application Extent — Walls
…7 unchanged lines
```
−## IBC Section 1805 requires that where a subsurface soil investigation indicates a hydrostatic pressure condition exists, walls shall be waterproofed with a system capable of resisting hydrostatic pressure.
−
−## Where hydrostatic pressure will not occur as determined by IBC Section 1803.5.4, dampproofing is the minimum requirement.
−
−## The design basis shall be explicitly documented in the contract documents so that the membrane type selection is traceable to a geotechnical basis.
−
−## An assembly sized only for non-hydrostatic conditions will fail under seasonal hydrostatic loading. {note}
−
−## The geotechnical engineer's report shall establish both the normal groundwater elevation and the expected seasonal high water table elevation.
−
−## Where the design groundwater condition is intermittently or continuously hydrostatic, the waterproofing membrane shall be capable of resisting the design hydrostatic head confirmed by the geotechnical investigation.
−
−## IBC Section 1805.3 requires that waterproofing be applied from the bottom of the wall or slab to not less than 12 in. above the maximum elevation of the design groundwater table.
−
## The remainder of the wall above the waterproofed elevation shall be dampproofed per Section 1805.2.2.
…71 unchanged lines
### The finished assembly provides a continuous sheet membrane that bonds directly to the prepared concrete or masonry substrate without heat, eliminating open-flame torch application in an occupied or confined work area. {note}
+### The minimum thickness of self-adhering sheet membrane at walls shall be specified based on whether the wall condition is hydrostatic or non-hydrostatic.
+
```datasheet
label: Self-Adhering Sheet Membrane — Minimum Thickness, Walls
…6 unchanged lines
```
+### Minimum membrane thickness for vertical walls in hydrostatic applications shall be 60 mil total thickness.
+
+### For non-hydrostatic applications, a minimum 40-mil sheet is acceptable for walls.
+
+### For underslab applications, a minimum 40-mil sheet is acceptable in non-hydrostatic conditions and 60 mil in hydrostatic conditions.
+
```datasheet
label: Self-Adhering Sheet Membrane — Minimum Thickness, Underslab
…6 unchanged lines
```
+### The manufacturer's published minimum thickness requirements for the specific application and hydrostatic head shall always govern where they are more stringent.
+
+### Laps shall be a minimum 3-in. side lap and a minimum 6-in. end lap for sheet membranes.
+
```datasheet
label: Sheet Membrane Lap Width — Side Lap (minimum)
…18 unchanged lines
```
−### Minimum membrane thickness for vertical walls in hydrostatic applications shall be 60 mil total thickness.
−
−### For non-hydrostatic applications, a minimum 40-mil sheet is acceptable for walls.
−
−### For underslab applications, a minimum 40-mil sheet is acceptable in non-hydrostatic conditions and 60 mil in hydrostatic conditions.
−
−### The manufacturer's published minimum thickness requirements for the specific application and hydrostatic head shall always govern where they are more stringent.
−
−### Laps shall be a minimum 3-in. side lap and a minimum 6-in. end lap for sheet membranes.
−
### Laps shall be firmly rolled with a minimum 50-lb weighted roller to consolidate the adhesive.
…7 unchanged lines
### However, fluid-applied systems require careful quality control over applied thickness, because a membrane that is applied too thin will fail under hydrostatic pressure, and thickness cannot be verified by eye. {note}
+### The minimum dry-film thickness of the fluid-applied membrane on walls shall be specified based on the hydrostatic head and traffic exposure the wall will experience.
+
```datasheet
label: Fluid-Applied Membrane — Minimum Dry-Film Thickness, Walls
…7 unchanged lines
```
+### The minimum dry-film thickness of the fluid-applied membrane underslab shall be specified based on the hydrostatic conditions at that location.
+
```datasheet
label: Fluid-Applied Membrane — Minimum Dry-Film Thickness, Underslab
…38 unchanged lines
### They are particularly useful in blindside configurations because they can be installed on the retained earth face of an excavation or lagging wall before the permanent concrete foundation is cast against them, and they do not require a primer or prepared concrete substrate. {note}
+### Bentonite GCL systems conforming to ASTM D8425 shall be lapped a minimum of 12 in. at all seams.
+
```datasheet
label: Bentonite GCL Minimum Seam Lap
…6 unchanged lines
```
+### Bentonite GCL systems shall have additional bentonite granules or bentonite strip sealer applied to all laps to ensure continuity of the clay layer through the seam.
+
+### At all edges, terminations, and penetrations, bentonite paste or a compatible sealant shall be applied to seal the edge of the GCL and prevent premature hydration from construction water before backfill.
+
+### Bentonite hydrated with saline water, high-mineral-content groundwater, or water with significant calcium or magnesium content will not swell to the same degree as bentonite hydrated with clean water, and the resulting membrane permeability may be higher than the design value. {note}
+
+### Where groundwater chemistry is unusual or where the soil contains significant concentrations of calcium-based materials such as cement, lime, or fly ash, the geotechnical engineer shall evaluate the compatibility of the groundwater with sodium bentonite.
+
```datasheet
label: Bentonite GCL — Groundwater Chemistry Review Required
…5 unchanged lines
```
−### Bentonite GCL systems conforming to ASTM D8425 shall be lapped a minimum of 12 in. at all seams.
−
−### Bentonite GCL systems shall have additional bentonite granules or bentonite strip sealer applied to all laps to ensure continuity of the clay layer through the seam.
−
−### At all edges, terminations, and penetrations, bentonite paste or a compatible sealant shall be applied to seal the edge of the GCL and prevent premature hydration from construction water before backfill.
−
−### Bentonite hydrated with saline water, high-mineral-content groundwater, or water with significant calcium or magnesium content will not swell to the same degree as bentonite hydrated with clean water, and the resulting membrane permeability may be higher than the design value. {note}
−
−### Where groundwater chemistry is unusual or where the soil contains significant concentrations of calcium-based materials such as cement, lime, or fly ash, the geotechnical engineer shall evaluate the compatibility of the groundwater with sodium bentonite.
−
### Bentonite membranes shall be held in place by the concrete or backfill before they become wet, because a GCL panel exposed to rain or standing water before the concrete is cast against it may swell, shift, or lose bentonite from cut edges, compromising continuity.
…6 unchanged lines
### This lateral-migration resistance is the primary advantage of bonded blindside systems over sheet membranes that rely on pressure contact alone. {note}
−```datasheet
−label: Pre-Applied Membrane — Minimum Lap Width
−type: select
−unit: in
−options:
− - "3 in."
− - "4 in."
− - "6 in."
−default: "4 in."
−```
+### Whether a lean concrete mud mat is required beneath the pre-applied membrane for horizontal underslab application, and its minimum thickness, shall be specified.
```datasheet
…11 unchanged lines
### Sheets shall be lapped per the manufacturer's requirements, typically a minimum of 4 in. at side laps.
+```datasheet
+label: Pre-Applied Membrane — Minimum Lap Width
+type: select
+unit: in
+options:
+ - "3 in."
+ - "4 in."
+ - "6 in."
+default: "4 in."
+```
+
### At inside corners and horizontal-to-vertical transitions, the manufacturer's transition reinforcement membrane and sealant shall be installed as shown on the detail drawings.
…6 unchanged lines
### The application requires trained personnel and safety controls for working with hot materials. {note}
+### Hot-applied rubberized asphalt shall be applied to the minimum thickness recommended by the manufacturer for the design hydrostatic head.
+
```datasheet
label: Hot-Applied Rubberized Asphalt — Minimum Applied Thickness
…7 unchanged lines
```
−### Hot-applied rubberized asphalt shall be applied to the minimum thickness recommended by the manufacturer for the design hydrostatic head.
−
### A reinforcing fabric may be embedded in the hot material at inside and outside corners, at construction joints, and at penetrations for additional bridging capacity.
…2 unchanged lines
# Substrate Preparation {toc}
−## General Requirements {toc}
+## A membrane applied to a poorly prepared substrate will delaminate, bridge over substrate defects, or puncture, regardless of the membrane's own material quality. {note}
−### A membrane applied to a poorly prepared substrate will delaminate, bridge over substrate defects, or puncture, regardless of the membrane's own material quality. {note}
+## Substrate preparation is the single most cost-effective quality investment in below-grade waterproofing. {note}
−### Substrate preparation is the single most cost-effective quality investment in below-grade waterproofing. {note}
+## All waterproofing surfaces shall be structurally sound, free of standing water, frost, oil, grease, curing compound not compatible with the membrane, form-release agents, dust, and loose or delaminated material before any primer or membrane is applied.
−### All waterproofing surfaces shall be structurally sound, free of standing water, frost, oil, grease, curing compound not compatible with the membrane, form-release agents, dust, and loose or delaminated material before any primer or membrane is applied.
+## The Contractor shall inspect every portion of the substrate before beginning application and shall not apply waterproofing over areas that do not meet the acceptance criteria.
−### The Contractor shall inspect every portion of the substrate before beginning application and shall not apply waterproofing over areas that do not meet the acceptance criteria.
−
## Concrete Substrate Preparation {toc}
…79 unchanged lines
### The Contractor shall verify the correct primer application rate with the technical representative.
−# Application {toc}
+# Environmental Conditions {toc}
−## Environmental Conditions {toc}
+## For most self-adhering and fluid-applied membranes, the minimum installation temperature is 40°F; for some high-performance fluid-applied systems, the minimum may be lower.
+## Cold weather slows adhesive cure, increases viscosity of fluid-applied products, and reduces adhesion of lap seams. {note}
−### For most self-adhering and fluid-applied membranes, the minimum installation temperature is 40°F; for some high-performance fluid-applied systems, the minimum may be lower.
−### Cold weather slows adhesive cure, increases viscosity of fluid-applied products, and reduces adhesion of lap seams. {note}
+## The membrane shall not be applied when the ambient air temperature or surface temperature is below the minimum installation temperature specified by the manufacturer.
```datasheet
…8 unchanged lines
```
+## Application below the published minimum temperature without the manufacturer's specific cold-weather application guidance shall not be permitted.
+
+## The membrane shall not be applied when wind conditions will cause premature skinning of fluid-applied products, blow debris onto the uncured membrane, or make sheet lap control impractical.
+
+## The substrate and ambient air shall be at least 5°F above the dew point to prevent condensation on the substrate before and during application.
+
```datasheet
label: Minimum Surface Temperature Above Dew Point
…6 unchanged lines
```
−### The membrane shall not be applied when the ambient air temperature or surface temperature is below the minimum installation temperature specified by the manufacturer.
+# Application Sequence {toc}
−### Application below the published minimum temperature without the manufacturer's specific cold-weather application guidance shall not be permitted.
+## Waterproofing shall be applied in a sequence that ensures continuity without skipping areas.
−### The membrane shall not be applied when wind conditions will cause premature skinning of fluid-applied products, blow debris onto the uncured membrane, or make sheet lap control impractical.
+## For walls, application shall begin at the bottom of the wall and work upward so that each sheet course laps over the top of the course below in a shingle pattern oriented to shed any water that migrates through the lap zone downward, not into the building.
−### The substrate and ambient air shall be at least 5°F above the dew point to prevent condensation on the substrate before and during application.
+## For underslab membranes, application shall proceed from the interior toward the perimeter so that the field laps shed water away from the building interior.
−## Application Sequence {toc}
+## The wall-to-slab or wall-to-footing transition shall be reinforced in all cases with a 12-in.-wide strip of self-adhering membrane or a trowel-applied sealant fillet before the field membrane is applied, regardless of whether the system is otherwise a fluid-applied or sheet system.
−### Waterproofing shall be applied in a sequence that ensures continuity without skipping areas.
+## The sequence shall ensure that the wall membrane and the slab membrane are physically lapped and bonded together at the wall-to-slab joint with no gap.
−### For walls, application shall begin at the bottom of the wall and work upward so that each sheet course laps over the top of the course below in a shingle pattern oriented to shed any water that migrates through the lap zone downward, not into the building.
+## The termination of the joint reinforcement strip shall not become a termination that is exposed to water.
−### For underslab membranes, application shall proceed from the interior toward the perimeter so that the field laps shed water away from the building interior.
+# Membrane Laps and Continuity {toc}
−### The wall-to-slab or wall-to-footing transition shall be reinforced in all cases with a 12-in.-wide strip of self-adhering membrane or a trowel-applied sealant fillet before the field membrane is applied, regardless of whether the system is otherwise a fluid-applied or sheet system.
−
−### The sequence shall ensure that the wall membrane and the slab membrane are physically lapped and bonded together at the wall-to-slab joint with no gap.
−
−### The termination of the joint reinforcement strip shall not become a termination that is exposed to water.
−
−## Membrane Laps and Continuity {toc}
−
```datasheet
label: End Lap Stagger Between Adjacent Courses (minimum)
…7 unchanged lines
```
−### All laps shall be consolidated immediately after application using a weighted roller or by hand pressure per the manufacturer's instructions.
+## All laps shall be consolidated immediately after application using a weighted roller or by hand pressure per the manufacturer's instructions.
−### Laps shall be rolled from the center outward to avoid trapping air.
+## Laps shall be rolled from the center outward to avoid trapping air.
−### Bubbles, wrinkles, and fish-mouths in sheet membrane laps shall be slit, pressed flat, sealed with a compatible sealant, and re-rolled.
+## Bubbles, wrinkles, and fish-mouths in sheet membrane laps shall be slit, pressed flat, sealed with a compatible sealant, and re-rolled.
−### Any lap area that cannot be made fully consolidated and flat shall be lapped over with a minimum 6-in.-wide patch of membrane overlapping all four sides of the defect.
+## Any lap area that cannot be made fully consolidated and flat shall be lapped over with a minimum 6-in.-wide patch of membrane overlapping all four sides of the defect.
−### End laps shall be staggered a minimum of 24 in. between adjacent courses to avoid a continuous vertical line of seams that concentrates stress and leak risk.
+## End laps shall be staggered a minimum of 24 in. between adjacent courses to avoid a continuous vertical line of seams that concentrates stress and leak risk.
−## Curing and Protection {toc}
+# Curing and Protection {toc}
−### Membrane exposed to extended UV radiation, foot traffic, or other trades' work without protection is vulnerable to damage. {note}
+## Membrane exposed to extended UV radiation, foot traffic, or other trades' work without protection is vulnerable to damage. {note}
−### No portion of the installed membrane shall be left uncovered at the end of each workday during construction.
+## No portion of the installed membrane shall be left uncovered at the end of each workday during construction.
−### At minimum, protection board shall be applied before any significant construction activity proceeds in the waterproofed area.
+## At minimum, protection board shall be applied before any significant construction activity proceeds in the waterproofed area.
−### For fluid-applied systems, the membrane shall cure to a minimum hardness per the manufacturer's cure schedule before protection board is applied.
+## For fluid-applied systems, the membrane shall cure to a minimum hardness per the manufacturer's cure schedule before protection board is applied.
# Detailing at Penetrations and Terminations {toc}
…46 unchanged lines
### Construction joints in concrete — including wall cold joints, horizontal pour joints, and wall-to-slab joints — are the most common leak path in below-grade concrete structures. {note}
+### The waterstop type at each below-grade construction joint shall be specified based on the hydrostatic-head condition at that joint.
+
```datasheet
label: Waterstop Type at Construction Joints
…7 unchanged lines
```
+### The minimum waterstop width at wall construction joints shall be specified based on the hydrostatic-head condition at each joint.
+
```datasheet
label: Waterstop Width at Wall Construction Joints (minimum)
…47 unchanged lines
### The termination of the waterproofing system at or above finished grade is the uppermost edge of the system and is a common location for peel-back, delamination, and water entry between the membrane and the substrate. {note}
+### The membrane shall be terminated at a height of not less than 8 in. above finished grade in non-hydrostatic conditions, and not less than 12 in. above the design high water table elevation in hydrostatic conditions.
+
```datasheet
label: Membrane Termination Height Above Finished Grade (minimum)
…7 unchanged lines
```
+### Terminations shall be mechanically fastened with a termination bar, or embedded in a saw cut, and sealed with a compatible caulk or sealant.
+
```datasheet
label: Membrane Termination Method at Grade
…6 unchanged lines
```
−### The membrane shall be terminated at a height of not less than 8 in. above finished grade in non-hydrostatic conditions, and not less than 12 in. above the design high water table elevation in hydrostatic conditions.
−
−### Terminations shall be mechanically fastened with a termination bar, or embedded in a saw cut, and sealed with a compatible caulk or sealant.
−
### The membrane shall not be terminated by simply folding the top edge over without mechanical fastening.
…12 unchanged lines
### The purpose of the protection course is to protect the membrane from mechanical damage during backfill and compaction operations, to shield the membrane from root intrusion in landscaped areas, and to distribute backfill loads rather than concentrating them on the membrane at backfill aggregate contact points. {note}
+### A protection course shall be installed over all waterproofing membranes before backfill, concrete placement over underslab membranes, or installation of drainage composites or insulation.
+
```datasheet
label: Protection Course Type — Vertical Walls
…17 unchanged lines
```
−### A protection course shall be installed over all waterproofing membranes before backfill, concrete placement over underslab membranes, or installation of drainage composites or insulation.
−
### Backfill without a protection course is not permitted.
…26 unchanged lines
### A drainage composite, also known as a drainage board or geocomposite drainage layer, provides a high-transmissivity flow channel between the waterproofed wall or slab and the backfill soil, directing water downward to the perimeter drain. {note}
−```datasheet
−label: Drainage Composite — Required on Walls
−type: radio
−options:
− - "Yes — drainage composite required on all waterproofed walls in hydrostatic or intermittently hydrostatic conditions"
− - "Yes — drainage composite required on all waterproofed walls regardless of groundwater condition"
− - "No — free-draining granular backfill of sufficient width used in lieu of drainage composite (only in non-hydrostatic conditions)"
−default: "Yes — drainage composite required on all waterproofed walls in hydrostatic or intermittently hydrostatic conditions"
−```
+### The minimum core thickness of the drainage composite shall be specified for use behind the waterproofed wall or slab.
```datasheet
…12 unchanged lines
### The drainage composite shall be installed against the protection course on the wall face, from the footing elevation to finished grade, with a filter fabric facing on the soil side to prevent fines migration into the drainage core.
+```datasheet
+label: Drainage Composite — Required on Walls
+type: radio
+options:
+ - "Yes — drainage composite required on all waterproofed walls in hydrostatic or intermittently hydrostatic conditions"
+ - "Yes — drainage composite required on all waterproofed walls regardless of groundwater condition"
+ - "No — free-draining granular backfill of sufficient width used in lieu of drainage composite (only in non-hydrostatic conditions)"
+default: "Yes — drainage composite required on all waterproofed walls in hydrostatic or intermittently hydrostatic conditions"
+```
+
## Perimeter Drain {toc}
…52 unchanged lines
# Testing and Inspection {toc}
−## Overview {toc}
+## A waterproofing system cannot be verified by visual inspection alone; testing identifies breaches that are not visible and that would not be found until water entry occurred after backfill and occupation. {note}
−### A waterproofing system cannot be verified by visual inspection alone; testing identifies breaches that are not visible and that would not be found until water entry occurred after backfill and occupation. {note}
+## Field testing of installed below-grade waterproofing is mandatory.
−### Field testing of installed below-grade waterproofing is mandatory.
+## Testing shall be performed before the membrane is covered by the protection course and before backfill begins.
−### Testing shall be performed before the membrane is covered by the protection course and before backfill begins.
−
## Flood Test {toc}
…37 unchanged lines
### The high-voltage dry method (ASTM D8231) applies a high-voltage pulse to a scanning electrode that is moved across the dry membrane surface and detects voltage discharge through membrane defects. {note}
+### The electronic leak detection method shall be specified, or that flood testing serves as the primary test method for this project.
+
```datasheet
label: Electronic Leak Detection — Method
…7 unchanged lines
```
+### The party responsible for performing electronic leak detection testing, and for reviewing the results, shall be specified.
+
```datasheet
label: Electronic Leak Detection — Performed by
…144 unchanged lines
## Backfilling before flood test and ELD is the single most damaging construction sequencing error in below-grade waterproofing because it converts a correctable deficiency into an excavation-and-reconstruction problem. {note}