Radon for Builders and Contractors

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Preventing hazardous levels of radon-gas exposure in any dwelling, residency, structure, building, etc. is best addressed before construction even begins. In using simple, inexpensive techniques, builders and contractors can provide immense added value to their projects and make a difference in people's health.

Radon-proofing: The Basics

Sealing and caulking

Patching up your concrete foundation's cracks, fissures, openings, crevices, etc. with high-quality sealant and/or caulking is a quick and inexpensive way to inhibit radon and other soil gases from making their way into your home; polyurethane caulk should be used for walls. Given that basements and crawl spaces are not the norm in South Africa, this radon-proofing method is an easy way to mitigate radon exposure risk in existing homes as well, since potential leakage areas are more easily accessible. 


Commonly referred to by builders and developers as an "air flow layer" or "gas permeable layer", a thin covering of fine, clean gravel, measuring about 10 cm and laid under a foundation, allows radon and other Naturally Occurring Radioactive Materials (NORM) to circulate uninhibited below a structure. The size of the gravel used should be a little under 2 cm. It cannot be stressed enough that gravel this size, uniformly, must be used; otherwise, air circulation under your foundation will be restricted, rendering this radon-proofing technique less effective. If gravel is not available or too expensive, using perforated pipe or a collection mat is also an option. 

Plastic sheeting

There are several important purposes for using plastic sheeting. By laying it between your concrete foundation or floor assembly and the gas-permeable layer, you:

  • stop concrete from spilling downward and congesting the gas-permeable layer​

  • reduce NORM entry by covering fissures and cracks in the foundation or floor assembly

  • decrease moisture and other NORM entry into a structure by acting as a vapor barrier. 

Plastic sheeting is inexpensive and easy to install.

  • take a polyethylene or a similar malleable sheet material.

  • placed the sheet material on top of the gas-permeable layer so that it covers the entire floor.

  • make sure that sections overlap each other by a minimum of 30 cm. 

  • wrap the sheet material snuggly around any protruding wires, pipes, or other fixtures. 

  • patch up punctures and cuts with either duct tape (for small, uniform tears and holes) or additional sheet material (for large rips). 

Vent pipe

These fixtures are becoming all the more common in the US and other countries that have strict radon regulations and extensive radon public awareness. 

Take a solid PVC Schedule 40 pipe about 10 cm in diameter and install it vertically from the gravel cover and through the structure's conditioned space and roof to vent radon and other NORM off into the atmosphere. 

Junction box (outlet)

Providing access to electricity in your attic with a junction box (outlet), coupled with a ventilation fan, can ensure added radon resistance to any structure, both before and after construction. 

Consultation and Implementation in South Africa

CareTac can guide builders and contractors in South Africa, from single-unit construction to large buildings and estates, on how to best radon-proof their projects using cost-effective techniques. Our locally trained experts follow best practices established internationally to ensure that our clients can the best advice available. If you are looking to radon-proof a future or existing project, contact us today