Do we really need a Radon Sump - no idea, but its cheaper just to build one, than it is to do the tests and find out if you need one. I had put a vent pipe through the foundations to drain the sump, and used the bobcat to scrape out a hole. Building the sump was a job my helpers really enjoyed doing.

First goes down some concrete for the bottom of the sump. We stick the first row of bricks directly into the concrete before it sets.

The other bricks are soon put in place.

Once its all set, a paving slab goes on the top, and its backfilled with rubble. The theory is that the radon from anywhere under the house collects in the sump, and then goes down the pipe, rather than vents up into the house.