If your Lynchburg home sits over a crawl space, radon can still find its way up into the rooms you live in. Radon is a colorless, odorless gas that comes from the natural breakdown of uranium in soil and rock. Crawl spaces are one of the openings it can use to enter a house.
This page explains how crawl space radon sealing works, what each part of the system does, and why sealing alone is not relied on. (434) 455-8258 connects you with licensed and insured local radon professionals who can look at your home and explain the options.
How radon reaches a home through a crawl space
Soil under and around a house holds radon gas. That gas moves toward lower-pressure areas, including the space under your floors. From a crawl space, it can drift up through gaps around pipes and wires, through the floor above, and through other small openings.
Any home can have a radon problem, whether it is new or old. A crawl space does not mean a home is safe, and it does not mean a home is at risk. Only a test can tell you which one applies to your house.
The sealed membrane
The main step in a crawl space system is covering the ground with a plastic membrane. The sheeting lays across the dirt floor and is sealed so that soil gas has a harder time entering the open crawl space air. The goal is to separate the air in the crawl space from the soil gas beneath it.
The membrane is not a standalone fix. It creates a covered area under which radon can be collected and moved away. That is where the vent comes in.
Venting from beneath the membrane
This method is called sub-membrane depressurization. A vent pipe is connected to the area under the plastic, and a fan draws the radon-laden air from there. The pipe carries it outside and releases it above the roof line, where it disperses in the open air.
It is the same idea as the active soil depressurization used in homes with basements or slabs. The difference is that the membrane takes the place of a concrete floor. Many systems also include a simple pressure gauge that shows the fan is running, which gives you an easy way to check on it.
Sealing openings is part of the system
A professional will often seal visible openings as part of the job. These can include gaps around pipes and wires, cracks, and other places where air moves between the crawl space and the house. Sealing helps the vent and fan do their work more effectively.
But the EPA does not recommend sealing cracks and openings as the only way to reduce radon. Gas can find new paths, and small gaps are hard to close completely. Sealing works best as one piece of a system, not as the whole plan.
Why sealing alone is not relied on
It can be tempting to caulk a few gaps and call it done. The problem is that this does not remove radon from beneath the home. It only blocks some of the routes in.
A system that pulls air from beneath the membrane and sends it outside tackles the source of the pressure. That is why a vent and fan are part of the standard approach for crawl spaces, with sealing supporting the work.
Lynchburg homes and conditions
Lynchburg is built across the foothills of the Blue Ridge Mountains, and the housing ranges widely. There are older homes in historic areas such as Daniel's Hill, Federal Hill, Garland Hill, Diamond Hill and Rivermont. There are also suburban subdivisions in Forest, Timberlake and Madison Heights. The same rule applies to all of them: any home can have elevated radon.
Virginia health officials note that high results have been found in every Virginia county, including counties rated low risk on EPA's map. Winter adds another reason to pay attention. With cool temperatures from roughly December through February, windows stay shut and houses stay closed up, which can affect the radon readings you see.
Help is available across the city and in nearby places such as Madison Heights, Forest, Timberlake and Rustburg, as well as the surrounding county.
Test first, then retest
Testing is the only way to know your home's radon level. The EPA recommends fixing a home at 4 pCi/L or higher and suggests considering a fix between 2 and 4 pCi/L. If you have not tested yet, start there.
After a system is installed, the EPA recommends retesting to confirm it is working. It also recommends retesting every two years or so, and after major renovations. If you are buying or selling, remember that a result from a previous owner may not reflect current conditions.
Choosing a qualified professional
Virginia law requires anyone doing professional radon testing or mitigation in the state to hold current certification from the National Radon Safety Board (NRSB) or the National Radon Proficiency Program (NRPP). Ask any contractor to confirm their certification before work begins.
Cost depends on your home's foundation type, size and layout, so professionals give a quote after looking at the crawl space. To talk it through, call (434) 455-8258 and be connected with a licensed and insured local professional.