I have a sump pit in my basement that I want to seal to reduce the radon levels which are around 6

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The problem is that all of the sump pit covers I have found are round. It seems like they won't work for this square type pit.

If I were to make a DIY cover, what materials should be used?

I plan on replacing my pump, but would like to avoid having a pro come in to install a modern sump pit with cover.

  • Might not be light, but you could create a concrete cover.
    – TFK
    Feb 3, 2016 at 13:46
  • 1
    I'm not sure radon mitigation is a DIY task.
    – Tester101
    Feb 3, 2016 at 16:35
  • I'm biased by my experience, but I think it often is feasible for the homeowner. I'm doing Radon mitigation in my home soon. I've found more than enough information on it to feel confident in the outcome, though I'm in a modern home with an interior drain tile system. Older homes with clay soil would be more difficult.
    – isherwood
    Feb 3, 2016 at 17:24

2 Answers 2


I would install a frame built out of treated lumber to support the lid. Anchor it to the concrete with construction adhesive and concrete screws (Tapcon). It appears that your pit is very shallow, so you may need to build the frame above the pit and surrounding it to gain height for the pump, etc. I'm thinking 2x4s against the walls and 2x10s oposite, flush on top.

Then, buy or build a polycarbonate lid using appropriate grommets for the penetrations. This company offers a great selection of parts (and a ton of good information). If you want to use one of their round covers, put a 3/4" treated plywood deck on your frame and cut a circular hole to match. Screw the lid on with a strip of foam tape underneath.

On a related note, Radon mitigation systems don't rely solely on barriers to Radon gas, per se, but airflow management. By venting underslab air, Radon is diluted and dissipated to a safe location. Simply sealing a foundation is unlikely to be successful. I'm assuming here that a fan or static suction mechanism will be installed.


You can create a basic cover for your sump pump by using a cast concrete patio paver. I am not sure what size you will need, but you should be able to find pavers locally that are up to 24x24.

Using a wet saw, you can cut a notch big enough to allow it to slide into place around the pump. After the cover is cut to size, you can place common bricks into the pit around the pump to support the cover. This will cover up 80% to 90% of the opening, which will probably be good enough. This style of cover will also allow the water to freely flow into the pit.

The biggest cost would probably be the rental of the wet saw. Some home improvement stores will cut the paver for you for free if you have the measurements, and you purchase the materials there. Most stores also have rental units as well which are pretty inexpensive if you only have it for a day.

  • 2
    OP wants a sealed cover for a Radon mitigation system. Masonry probably won't do here.
    – isherwood
    Feb 3, 2016 at 16:16

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