A construction worker in a gray uniform is applying a vapor intrusion barrier system on site.


Vapor intrusion is a vital safety concern that can impact building development or renovation. It refers to the vapor-forming chemicals present in soil that can enter a building through surfaces such as floors or basement walls. For any type of project, it is essential that the right testing and screening is conducted before construction starts so suitable products or systems can be put in place to keep the harmful vapors out.

When planning a construction or renovation project over soil that might be environmentally impacted, you want to be knowledgeable enough to make sure that problems such as vapor intrusion are addressed and prevented. Failing to do so can cause serious health issues and impact the value of the structure.

Working with experts, such as environmental consultants, will help you address issues and ensure safety. These individuals carry out exhaustive vapor intrusion testing and screening, and building envelope experts can help you find the right products to protect the structure if vapors are detected.

What is Vapor Intrusion?

The term ‘vapor intrusion’ refers to when vapor-forming chemicals migrate from any subsurface source into an overlying building, according to the EPA. While some vapors may be harmless, more dangerous contaminants can often enter buildings.

Such contaminants include volatile organic compounds (or VOCs) like benzene, methane and trichloroethylene (PCE). They are often found in soil as a result of pollution or other industrial contamination.

Vapor Intrusion Testing and Screening

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Vapor intrusion testing involves collecting samples of gasses from the soil on a building site, or even the adjacent property. The screening process then involves analyzing the samples to determine whether or not the site concentrations are safe for occupants of the new structure and what kind of vapor intrusion mitigation solutions may be required. The ASTM has specific standards in place to determine what levels are safe for humans.

Testing typically involves drilling holes into the ground below a building (known as sub-slab vapor sampling) and extracting any gasses from the soil via a sealed vacuum cylinder or summa canister. This usually takes place over the course of several hours to a whole day. It is necessary to test when contaminant vapor intrusion is suspected due to previous site investigations. Onsite, chemical odors would be the obvious sign that a vapor intrusion issue is present.

Onnce the samples have been extracted, screening takes place. The level of chemicals in the soil are compared to a standard reference point, using a a Vapor Intrusion Screening Level (VISL) calculator developed by the EPA. If high levels of volatile and/or toxic contaminants are found, the EPA may conduct an investigation to determine how the soil was contaminated.

The VISL calculator provides screening-level concentrations for groundwater, near-source soil gasses, sub-slab soil gasses, and indoor air. The standards are based on complex metrics including exposure scenarios, a target cancer risk level of one in a million and a target non-cancer-related hazard quotient of 0.1.

The parameters provided by the EPA’s VISL calculator are a point of reference, but they should be altered to reflect more site-specific scenarios if needed. For example, acceptable concentrations can differ based on the type of project, more specifically, whether the development is resential. For more detailed information on how the calculator works, visit the EPA website.

Why are Vapor Intrusion Testing and Screening So Important?

Vapor intrusion can cause many serious problems, from health issues to building damage at the structural level. Minor health concerns for building occupants include headaches, nausea and irritation of the eyes, skin or throat.

In more serious cases, contaminant vapors can even increase the risk of cancer. Benzene and TCE, for example, are known carcinogens, and radon is the top cause of lung cancer in non-smokers. Other potential effects of exposure to harmful vapors include liver, kidney and heart damage, reproductive issues, and damage to neurological and cognitive function.

Vapors such as methane or petroleum-based chemicals are highly flammable and can dramatically increase the risks of fires or explosions.

Due to these risks, contractors and developers not only have a moral responsibility to take the necessary steps to protect public health, but they can also be professionally and legally liable for any issues that occur as a result of inadequate safety measures.

What to Do If Vapor Intrusion is Detected on a Site

Installing a vapor intrusion mitigation (or VIM) system such as a vapor intrusion membrane is the most common way to protect a building from these threats. Vapor intrusion membranes consist of one or more durable waterproof layers that prevent vapors from migrating into a building. They can also be used in conjunction with vapor collection systems if required by site conditions.

Choose EPRO To Help Keep Projects Safe

A construction worker on site applying a vapor intrusion barrier.


At EPRO, we have three decades of experience in providing durable, long-lasting waterproofing and vapor intrusion solutions for construction and renovation projects of all kinds. We understand how difficult it can be to determine and solve issues with contaminant vapor intrusion, and our experts can help you to do so — whatever the site-specific conditions of your project.

We can provide solutions for various different projects, whether on brownfield or greenfield sites:

  • Geo-Seal® 100: The most chemically-resistant composite vapor intrusion barrier on the market, the Geo-Seal 100 consists of three layers — a base, a 60-millimeter core and a bond.

  • Geo-Seal EV80: An EVOH composite vapor intrusion barrier, the Geo-Seal EV80 includes an EV30 layer, a core layer and a bond layer.

  • Geo-Seal 60: The most cost-effective composite vapor intrusion barrier available, the Geo-Seal 60 also includes three durable layers.

  • Geo-Seal EV40s: A single-sheet geocomposite barrier, the Geo-Seal EV40s outperforms other single-sheet layers available and is ideal for lower-risk projects.

  • Geo-Seal EFC: A chemically-resistant VIM epoxy coating, Geo-Seal EFC is ideal for application to existing structures, particularly concrete floors.

  • Vapor-Vent™: A composite vapor collection system designed for sub-slab installation.

Choosing the ideal VIM system for your project can be tricky, but our team of highly-qualified experts can offer advice, recommendations, and support every step of the way.

Our experts remain available for additional support even after the system has been installed and the project is complete.

So if you're interested in working with us on your next project, contact our team today!