NOTE This standard covers the materials, surface preparation, and application of dampproofing on below-grade foundation walls, retaining walls enclosing interior space, and slabs-on-grade where the groundwater investigation confirms no hydrostatic pressure. (1.1)

NOTE Dampproofing resists the capillary movement and vapor transmission of soil moisture; it is not a pressure-resistant barrier. (1.2)

NOTE Dampproofing and waterproofing are different systems selected on a single threshold: the presence or absence of hydrostatic pressure. (1.2.1)

NOTE Dampproofing is a moisture-resistant treatment that slows the wicking and vapor diffusion of soil moisture through a foundation. It is applied at low film thickness, is not designed to bridge cracks, and is not designed to hold back standing water. Waterproofing, by contrast, is a continuous, crack-bridging, pressure-resistant membrane required wherever a head of water can stand against the structure. The International Building Code makes this distinction the governing decision: IBC Section 1805.2 permits dampproofing only where the groundwater investigation required by Section 1803.5.4 establishes that a hydrostatic condition does not exist. Where seasonal high groundwater can reach the structure, dampproofing is not permitted and a waterproofing system per Below Grade Waterproofing or Fluid Applied Waterproofing is required instead. (1.2.2)

NOTE The 80% application this standard addresses is a residential or light-commercial basement or crawl-space foundation wall on free-draining soil, with a footing drain, treated with cold-applied asphalt emulsion over poured concrete and a 6 mil polyethylene vapor retarder beneath the slab. (1.2.4)

NOTE Dampproofing always works as part of a moisture-management assembly, not in isolation. (1.3)

NOTE The dampproofing coating, the granular backfill, and the foundation drainage system are interdependent; specifying one without the others undersupports the assembly. (1.3.1)

NOTE A dampproofing coating relieves capillary moisture but cannot survive a continuously saturated backfill. The coating is paired with free-draining backfill and a footing drain so that water is conducted away from the wall before it can build a head against it. Where backfill is poorly draining, where the water table is uncertain, or where a finished interior space below grade cannot tolerate any moisture, the correct response is to upgrade to waterproofing and a drainage composite, not to add coats of dampproofing. Coordinate the drainage side of this assembly with Foundation Drainage. (1.3.2)

NOTE This standard does not cover full membrane waterproofing for hydrostatic conditions, which is specified in Below Grade Waterproofing and Fluid Applied Waterproofing. (1.4.1)

NOTE This standard does not cover drainage composites, drain board, drain tile, or footing drains, which are specified in Foundation Drainage. (1.4.2)

NOTE This standard does not cover above-grade wall vapor retarders (Class I, II, and III), which are specified in Vapor Retarders. (1.4.3)

NOTE This standard does not cover integral crystalline waterproofing admixtures used as pressure-side waterproofing, which are specified in Below Grade Waterproofing. (1.4.4)

NOTE This standard does not cover roof dampproofing or above-grade flashing systems, which fall outside the below-grade envelope scope. (1.4.5)

NOTE Most cold-applied asphalt emulsions and water-based coatings require a clean, dry, frost-free substrate and an ambient and substrate temperature above approximately 4 °C (40 °F) and rising, so that the emulsion can break and cure. Applying these products to a wet or frozen wall is the leading cause of adhesion failure and the contractor disputes that follow. Hot-applied asphalt tolerates cooler substrates but introduces its own hazards from the application temperature near 93 °C (200 °F). Confirm the manufacturer's limits and the expected site conditions before selecting the material. (5.1.2)

NOTE The dampproofing material is selected from three families — bituminous, cementitious, and under-slab polyethylene — based on the substrate, the exposure, and whether the surface is vertical or horizontal. (6.1)

NOTE Bituminous dampproofing comprises hot-applied asphalt, cold-applied asphalt emulsion, and fibrous (mineral-reinforced) asphalt; these are the common treatments for vertical foundation walls. (6.1.1)

NOTE Cementitious dampproofing comprises acrylic-modified cement slurry and surface-bonding mortar; these are favored on unit masonry and where a paintable, non-bituminous surface is wanted. (6.1.2)

NOTE Polyethylene sheet dampproofing is used horizontally beneath slabs-on-grade as an under-slab vapor retarder; it is not a wall coating. (6.1.3)

NOTE ASTM D449 classifies dampproofing asphalt by softening point and flow. Type A (dead-level) and Type B (flat) are formulated for horizontal and low-slope surfaces and will sag or flow on a wall. Type C (steep asphalt), with a softening point of approximately 85 °C to 96 °C (185 °F to 205 °F), is the correct selection for vertical foundation walls because it holds a film on a vertical face without running. Specifying Type A on a wall — a common error — produces a coating that slumps and thins as it warms. (6.2.2)

NOTE The acrylic-modified cement family — sometimes called a cementitious coating or a polymer-modified slurry — is an IBC-recognized dampproofing material for masonry. IBC Section 1805.2 cites an application of 3 lb per sq yd (about 1.63 kg/m²) as the reference rate. It is favored where a non-bituminous, paintable, light-colored surface is wanted on the interior or exterior, and it bonds well to a properly prepared masonry or concrete face. It is not a crack-bridging membrane and is not a substitute for waterproofing. (6.3.2)

NOTE IBC Section 1805.2.3 and IRC R406 permit a minimum 6 mil polyethylene sheet beneath slabs-on-grade as the floor dampproofing element. ASTM E1745 grades these sheets into Classes A, B, and C by tensile strength and puncture resistance; the 6 mil residential default corresponds to the lowest class, while commercial slabs and slabs receiving moisture-sensitive flooring are commonly specified at 10 mil or 15 mil (Class A) for greater durability during placement. The sheet is installed in direct contact with the prepared base course, with joints lapped not less than 152 mm (6 in.) and sealed per ASTM E1643. (6.4.2)

NOTE The single most common dampproofing RFI is "how high does the coating go?" The answer is fixed by the relationship between the top-of-footing elevation and the finished-grade line: dampproofing covers the full earth-retaining height of the wall on its exterior face, from the top of the footing up to grade, plus a cove treatment at the footing-wall junction. Showing both elevations on the foundation drawing removes the ambiguity. Where a wall encloses interior space, the full earth-retained height is treated; where a wall is a crawl-space stem only, the extent still runs footing to grade but the interior treatment may differ. (7.2)

NOTE The location and routing of the treated extent — which walls, which faces, and the grade line itself — are coordination items that can never be reduced to a catalog value, so they are fixed on the drawings rather than in a datasheet field. See foundation plan and sections — walls and faces to be dampproofed. (7.2.5)

NOTE Surface preparation is where most dampproofing failures begin: an unpatched form-tie hole or an unparged masonry face is a direct moisture path that no thickness of coating will close. (8.1)

NOTE IBC Section 1805.2.2 requires that the concrete surface be prepared and that tie holes be sealed before dampproofing. A snapped form tie leaves a through-wall void on the line of least resistance for moisture; coating over it merely hides it. Fill tie holes and voids with a compatible bituminous patching material or an approved non-shrink or cementitious patch, struck flush, and allow the patch to cure before coating. (8.2.2)

NOTE A concrete masonry face is a field of mortar joints and open block voids; a thin coating cannot bridge that texture. IBC Section 1805.2.1 and IRC R406.1 therefore require unit masonry to be parged with not less than a 3/8 in. Portland cement mortar coat, coved at the footing, and then dampproofed. Parging is a surface-preparation step that belongs to this work unless the drawings assign it to the masonry trade; omitting it and coating bare block is a non-compliant, leak-prone shortcut. Where parging is performed by the masonry trade, coordinate the responsibility on the drawings so it is neither duplicated nor dropped. (8.3.2)

NOTE Where surface-bonding mortar conforming to ASTM C887 is used as the dampproofing material, a separate parge coat is not required because the bonding mortar performs the same function. (8.3.6)

NOTE A dampproofing coating is thin and is easily gouged by angular backfill or torn by a plate compactor working close to the wall. Damage during backfill is one of the leading callback causes for below-grade moisture. A protection course — a rigid protection board, a board of rigid insulation, or a dimpled drainage mat — is installed over the cured coating before backfill to take that abuse. A dimpled drainage mat additionally creates a drainage plane; where a drainage plane is required as part of the moisture-management assembly, coordinate it with Foundation Drainage rather than relying on the protection board alone. (9.3.2)

NOTE Dampproofing relieves capillary moisture; the footing drain and free-draining backfill relieve the water that would otherwise build a head against the wall. The two are specified and detailed together. (10.1)

NOTE Dampproofing is a low-cost, concealed treatment whose warranty is necessarily modest; a long warranty is the signature of waterproofing, not dampproofing. (13.1)