Let’s start with the simple answer: A waterproofing membrane is designed to resist water under hydrostatic pressure. A dampproofing coating is designed to resist soil moisture and water vapor only.
The two are not interchangeable, and the International Building Code treats them as separate scopes of work with separate requirements.
What does dampproofing actually do?
Dampproofing slows the migration of moisture from damp soil into a foundation wall. It is typically a thin, spray-applied asphaltic coating with a dry film thickness measured in a few mils. It is inexpensive, fast to install, and adequate when the code allows it.
Dampproofing coatings, however, are not formulated to resist hydrostatic pressure, and they have little ability to bridge cracks in concrete.
What makes a waterproofing system different?
Waterproofing forms a continuous barrier to keep water out of a structure. It is designed to be strong enough to withstand hydrostatic pressure AND protect the structure underneath. Yet it’s not the materials alone that keep water out – there are many points of weakness where a system can fail. It is imperative to make sure that seam detailing, penetrations, and transitions are completed correctly to maintain continuity across the entire below-grade envelope.
Waterproofing materials are also held to different standards than dampproofing. Fluid-applied waterproofing membranes, for example, are tested under ASTM C836 for properties like adhesion, low-temperature flexibility, and crack bridging.
Reference the correct building code for waterproofing and dampproofing requirements.
Under the 2024 International Building Code, if a groundwater investigation confirms hydrostatic pressure and the design does not include a groundwater control system, Section 1805.3 requires the walls and floors to be waterproofed. (Here is the reference for this)
How does EPRO approach waterproofing?
EPRO manufactures waterproofing systems for building protection:
E.Series composite systems layer field-installed membranes with drainage and protection materials.
HydroGel is a hot spray-applied polymer rubber gel that stays flexible for the life of the structure, making it self-sealing and well suited to both new construction and restoration.
PreTak is a pre-applied HDPE membrane that bonds directly to freshly placed concrete or shotcrete in blindside and underslab conditions.
PrimeTak is a post-applied, 60-mil peel-and-stick membrane for foundation walls, split slabs, and plaza decks.
The bottom line
Dampproofing manages moisture. Waterproofing manages water. If there is any realistic chance of water pressure against the foundation over the life of the structure, a waterproofing system is the right answer.
We know waterproofing. Reach out to the EPRO team today for waterproofing system guidance and to work with us on your next project.