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Large-Scale or Commercial Radon Testing

HUD & AARST Standards

From multi-unit residential radon testing to large commercial office spaces, we have you covered!


Radon Bid and design work are available for testing procedures for both HUD and AARST standards.


We have tested 490-unit apartment buildings and commercial buildings with a basement as large as 95,000 square feet!


When HUD is involved, there are two standards used for large-scale buildings.  At Reliable, we are capable of designing programs to meet both sets of requirements, clearing the way for your HUD financing.

We can help design the testing program and get results quickly, smaller projects can be done with our equipment or we can ramp up to do as much as you need on your schedule by using outside testing equipment and lab.


We have 5 NRPP-listed testers on staff so no project is too big. We do testing in Delaware, Pennsylvania, and Maryland.


Smaller Commercial buildings can get their results in as little as two days business days, and Larger buildings/sites within 5 business days. The chart below is a good tool for interpreting radon test results. We recommend mitigation for any level above 4.0 pCi/l, as is the EPA action level.

Radon EPA Color V2.PNG
Our inspectors are NRPP certified

How to Prepare for a Radon Test

To ensure your radon test is accurate there are some ways you should prepare for the test. The building should be kept in closed conditions for the duration of the test, as well as the 12 hours before the test. This means all windows in the building should be closed, and exterior doors should remain shut except for normal exit and entry. Open windows and doors could invalidate your test.


If the test is for a residential building, you should notify your tenants before the testing date. We can provide radon testing flyers that can be posted and emailed to your tenants. 

Any equipment that is lost or thrown out during the test may incur charges.

Delaware Daycare Radon Testing

All licensed childcare providers in Delaware are required to test for radon at least once every five years between October and March. Childcare facilities must also test within 6 months of renovations, remodeling, and construction. This section is a snippet, for more information on Reliable daycare radon testing, please see a dedicated page here.

Testing Procedure

For a residential building being used for child care, a test should be placed in every room used for child care that is in contact with the ground, or the lowest level used for child care. 

For buildings designed for child care, every classroom on the first floor should be tested. 1/4 of classrooms on a second floor should be tested. 

A short-term radon test must run for at least 48 hours in the test location. During this time windows and doors must be kept shut except for normal exit and entry. 

A qualified radon tester can help you build a procedure to meet all State requirements. The button below is a list of qualified testers in Delaware.

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