Epro underlayment system being installed.

Environmental health and safety is an increasing concern for architects, developers, contractors and governments. Recently, attention has turned towards vapor intrusion as a critical issue that should be addressed in order to safeguard the health and well-being of our communities.

What Is Contaminated Vapor Intrusion?

Vapor intrusion is caused by contaminated land or soil. Chemicals will convert or volatilize into vapor.

When buildings are constructed where there is contaminated soil or groundwater, vapor intrusion may occur when these contaminants migrate from the subsurface into the overlying building. According to the EPA, vapor-forming chemicals of concern may include:

  • Volatile Organic Compounds (VOCs) (e.g. trichloroethylene (TCE), tetrachloroethylene (PCE), benzene)
  • Certain semi-volatile organic compounds (e.g. naphthalene)
  • Elemental Mercury
  • Certain polychlorinated biphenyls and pesticides

Additionally, gases such as radon and methane can also create a vapor intrusion condition that can impact human health.

Vapor intrusion mitigation is possible, however, through building design, construction and maintenance interventions.

Why Is Vapor Intrusion a Cause for Concern?

On average, Americans spend 90% of their life indoors. As reports of sick building syndrome spread and the effects of pollutants on health continue to be studied, there is renewed attention on how building design and construction can improve indoor air quality and contribute to healthy and safe communities.

Vapor intrusion can cause a range of health and safety concerns:

1. Risk of fire or explosion

Vapor intrusion can create risks of fire or explosions occurring in the home. While this is rare, build-ups of methane gas or petroleum products can ignite or explode under certain conditions.

Fire alarm on wall.

Source: Unsplash

2. Acute health effects

Residents may experience acute health effects as a result of vapor intrusion, such as headaches, nausea, itchy eyes or throat irritation.

3. Cancer risks

Vapor intrusion first rose to national prominence in the 1980s, when the link between lung cancer and radon was identified. According to the EPA, radon is the number one cause of lung cancer for nonsmokers and contributes to over 20,000 deaths annually. Additionally, Benzene and TCE vapor are known carcinogens in humans.

4. Risks for vulnerable populations

The health impacts of vapor intrusion are particularly high for young children, the elderly, pregnant women and people with pre-existing chronic illnesses. For example, vapor intrusion has been linked to cardiac defects and low birth weights due to maternal exposure. Vapor intrusion, therefore, puts at risk already vulnerable people and can present additional challenges for public health.

5. Long-term impacts

While research into the long-term impacts of vapor intrusion continues to be undertaken, there is evidence that long-term exposure to some contaminants can impact cognitive and motor function, play a role in various types of cancer, cause damage to the liver and kidneys and damage immune function. Evidence also suggests that even low levels of exposure over a long period of time may cause neurological and neurobehavioral impacts.

Medical monitoring device.

Source: Unsplash

6. Reduced livability

While health concerns are naturally the most pressing impacts of vapor intrusion, the presence of chemicals in the home can also simply make it a less pleasant place to live. If certain chemicals are present, for example, hydrogen sulfide, residents may complain of unpleasant odors. These factors can make a building or unit less desirable and may lead to difficulties in selling or renting.

7. Building development challenges

Because of the health and safety concerns associated with vapor intrusion, it can present a challenge when developing a new site (particularly brownfield construction). Potential sources of contamination can be due to common sources (e.g. gas stations, dry cleaning contamination, manufacturing, etc.), and therefore, vapor intrusion can potentially impact any building site.

Because of the potential impacts vapor intrusion can have on the health of residents and the property value, vapor intrusion mitigation should be a key consideration for any development.

Vapor Intrusion Mitigation

Epro vapor intrusion system being installed.


In order for vapor intrusion to occur, there must be a pathway for gases to migrate along from the substrate into the building. Vapors primarily enter a building through gaps in the building’s foundation or basement walls. Common examples include cracks in concrete slabs, gaps around utility lines, etc. Vapors may also pass through concrete because of its naturally porous properties. This is known as advective flow. Vapors may also migrate through diffusion. Where the contaminant vapor may migrate from high concentrations under the building foundation into the indoor environment.

There are a number of approaches to vapor intrusion mitigation, including remediation of the contaminant source, addressing cracks and gaps in existing structures, and physically removing vapor from under the building foundation though mechanical means.

But it is also possible to plan for vapor intrusion mitigation at the beginning of a building’s design. Contaminant vapor barriers offer protection against vapor intrusion through the installation of a contaminant vapor intrusion barrier in the substrate to prevent the migration of harmful gases into the building.

EPRO has extensive experience in providing the right solution to meet the demands of a given project. These include:

Vapor Impermeable Waterproofing Barrier

Formed by using a geo-membrane, spray applied asphalt membrane and a bentonite liner, this waterproofing barrier is a multi-layer sheet system that self-seals and expands. In addition to creating a high-performance waterproof system, it is also contaminant vapor impermeable.

Applications include almost all below-grade concrete structures — this may include free-standing walls, under slabs, tunnels, elevator pits, as well as blindside applications such as lagging, caissons, sheet pile and shotcrete retention system.

Fluid-Applied Vapor and Water Barriers

Our E.Protect+ underslab protection system provides the most redundancy and highest level of below-grade building protection available. Designed for waterproofing and vapor intrusion, it combines three layers into one system for ultimate protection against hydrostation conditions, chlorinated VOCs and petroleum hydrocarbons.

It’s designed for buildings that require the highest level of performance, and it is compatible with all building foundation types, including pile, pad, mat, strip footings, grade beams, and buildings with moisture-sensitive flooring or finishes.

E.Protect+ consists of three layers: e.base 316, e.spray and e.shield 205b. Click here to learn more about this high-performance composite system.

Vapor Intrusion Barriers

EPRO offers several options for vapor intrusion barriers, which can eliminate vapor intrusion for brownfields or any evnironmentally-impaired sites, all in the Geo-Seal® product line.

Geo-Seal® 100 is a redundant composite vapor intrusion system that consists of three layers: Geo-Seal® BASE, Geo-Seal® CORE (60 mil) and Geo-Seal® BOND. Geo-Seal® 100 can withstand the rigors of your construction site, providing high puncture resistance and robust seals around penetration and terminations.

Geo-Seal® EV80 is a slightly thinner (but still thick at 79 mils) composite membrane system. It is ideal for projects where you are willing to compromise on total system thickness and some barrier durability but still desire a highly chemically resistant barrier. And it also consists of three layers: Geo-Seal® EV30, Geo-Seal® CORE and Geo-Seal® BOND.

Geo-Seal® 60 is a cost-effective alternative to Geo-Seal® 100 and Geo-Seal® EV80. It provides more resistance to construction traffic than a simple single sheet membrane, as well as more robust seals around penetrations and terminal points — all at a similar price point to single sheet membranes. It also consists of three distinct layers: Geo-Seal® FILM 11, Geo-Seal® CORE and Geo-Seal® BOND.

Building Vapor Intrusion Mitigation Into Your Project

In an area where our knowledge is still developing, it can be hard to know what’s the right decision to make when it comes to including contaminant vapor barriers into your project design and construction. That’s why it’s important to turn to experts in the waterproofing industry.

ERPO’s team of experts are on hand to answer your question about vapor intrusion and to collaborate with you on your project.