Why New Construction Should Plan for Soil Gases Upfront

A new home starts with decisions that will shape how the building performs for decades. Builders plan where plumbing will run, how water will drain, and where electrical systems will go before concrete and finished walls make those decisions harder to change. Soil gas control deserves the same early attention.

Radon and other gases in the soil can move toward a building and find pathways through its foundation. New construction should plan for soil gases upfront because it gives builders a chance to create a controlled route for those gases before completing the slab, flooring, and walls. It can also make future radon mitigation far simpler if testing shows that the building needs an active system.

Why Soil Gas Planning Starts at the Foundation

A building interacts with the ground beneath it from the moment the foundation goes in. Radon occurs naturally in soil and can enter a home through openings in the foundation, including cracks, joints, and penetrations.

New construction provides a valuable opportunity because the area beneath the slab remains accessible before the concrete pour. Builders can install components that help collect and direct soil gases without cutting through a finished slab later.

The industry refers to this approach as radon-resistant new construction, or RRNC. It does not guarantee that the building will have low radon levels, which is why testing still matters. Instead, it gives the building infrastructure that can make radon control easier if high levels appear after construction.

Waiting Until After Construction Changes the Job

New construction should plan for soil gases upfront because retrofitting a finished building comes with constraints that do not exist on an open construction site. The slab is already in place, finished rooms may limit pipe routes, and exterior aesthetics can affect where system components can go.

Planning early allows builders to consider those details alongside plumbing, electrical work, HVAC equipment, and the rest of the building layout. That coordination can create cleaner installation options and reduce the amount of alteration necessary later.

What Radon-Ready Construction Includes

A basic radon-ready design creates a pathway for gas beneath the building and a route for venting it outdoors. Depending on the foundation and project specifications, that pathway may use aggregate, perforated pipe, or a geotextile collection mat.

These components form the foundation of a soil gas mitigation system that builders can incorporate into the construction plans during the project. PDS Radon Supply’s Soil Gas Collector Mat, sometimes called a radon mat or vapor mat, installs below the slab without requiring soil preparation. It requires no backfill, no trenching, and no barrier, which can simplify installation during new construction.

Create a Collection Path Below the Slab

Soil gas needs a pathway to move beneath the building. A gas-permeable layer lets the system collect gas across the sub-slab area rather than relying on a single isolated point.

Traditional designs may use a layer of clean aggregate or perforated piping. A geotextile soil gas collector mat provides another approach. Because the material goes down before the concrete pour, builders can integrate it into the foundation sequence rather than trying to create collection points after finishing the structure.

PDS’s Soil Gas Collector Mat is a one-inch-thick geotextile drainage mat for sub-slab communication. Unlike installation methods that require excavation or additional material beneath the slab, the SGC Mat does not require trenching, backfill, or a separate barrier. This can reduce site preparation while still creating a pathway for soil gas movement beneath the building.

Plan the Vent Route Before Walls Close

Collection below the slab is only part of the system. The building also needs a route that allows gases to travel safely from the collection area to an exterior discharge point.

Planning the vertical vent stack during framing gives builders more control over where the pipe travels. They can account for mechanical spaces, chases, roof penetrations, and occupied rooms while those areas remain open.

An interior route can also help preserve the exterior appearance of the building. Rather than adding visible piping after construction, the vent can become part of the original building layout.

Prepare for Active Venting From the Beginning

Builders can create a radon-ready system so that it is easy to activate when necessary. That preparation matters because the completed home still needs radon testing.

If testing identifies elevated radon levels, a radon fan can create active suction and move soil gas through the vent system. Planning the fan location and electrical access during construction makes that upgrade much more straightforward.

Think Beyond the Components Under the Slab

A successful design depends on how the pieces work together. Builders should consider the collection material, vertical risers, vent routing, foundation sealing, electrical access, and potential fan placement as parts of one coordinated installation.

Key planning considerations include:

• Establish the sub-slab collection pathway before the concrete pour.
• Coordinate risers and vent piping with the building layout.
• Seal foundation penetrations and other potential gas-entry points.
• Provide an appropriate location and power source for future fan activation.
• Keep system components accessible where future inspection or service may be necessary.

Handling these details during design and construction can reduce conflicts between trades and make the system easier to understand.

Radon-Ready Does Not Replace Radon Testing

Making a building radon-ready is about preparation, not proof of the home’s indoor radon level. Radon levels can vary from one building to another, even when the homes are close together.

Even a home built with radon preparation in mind requires testing. This provides the information necessary to determine whether the passive features are sufficient or whether the system requires active venting with a fan.

That distinction matters for homeowners as well as builders. A radon-ready home already has important infrastructure in place, but homeowners should not assume that construction features eliminate the need to measure indoor radon.

Soil Gas Planning Also Requires Project-Specific Decisions

Not every foundation is identical. Slab-on-grade homes, basements, crawl spaces, multifamily projects, and commercial buildings can require different installation details.

Local building requirements may also affect the design. Builders, architects, and contractors should check applicable codes and radon-resistant construction standards before selecting materials or finalizing system details.

Projects involving soil contaminants or gases beyond radon may require additional evaluation. Certain volatile organic compounds or other soil gases can create material compatibility or safety considerations that the project’s environmental professionals or engineers should review.

Build Soil Gas Control into the Construction Process

The easiest time to create a pathway beneath a slab is before the slab exists. The same principle applies to vent routing, electrical preparation, and other features that become more difficult to add after completing construction.

Treating radon-ready features as part of the original building plan helps contractors coordinate the work with the rest of the project. It also gives future homeowners a practical way to respond if post-construction testing shows that active radon mitigation is necessary.

Build Radon Ready From the Start

New construction gives builders an opportunity that disappears after completing the foundation and finishes. By planning soil gas collection, venting, sealing, and future fan activation upfront, a project can prepare for radon mitigation without requiring the same level of retrofit work later.

PDS Radon Supply offers Soil Gas Collector Mat and radon-ready construction components for residential and commercial projects. Explore PDS’s Build Radon Ready resources to learn more about Soil Gas Collector Mat, installation details, submittal documents, and project takeoff support.

Planning a radon-ready project? Request a free SGC Mat quote and takeoff to estimate material needs and pricing. Orders starting at 150 pounds may also benefit from LTL freight shipping.