Sealing a sump lid can seem like an unnecessary chore. If you seal your sump lid with a permabond sealant, then what happens when the pump dies or you have to service it? Sealing with silicone means that you’ll have to cut the seal anytime the system needs maintenance. Unfortunately, for radon system efficiency and indoor air quality, sealing your sump lid is a good idea.
Energy efficiency
An active radon system that pulls from a sump, interior drain, or exterior drain, will pull from the path of least resistance. An efficient radon system only extracts soil air and works in conjunction with a well-sealed floor, crawlspace, or other foundation type. When there are holes in this system, you lose efficiency and you extract conditioned air from inside the home. Conditioned air is air that you pay to heat or cool. Radon fans move a tremendous volume of air. Even low flow fans move dozens of cubic feet of air per minute (cfm). A cfm is about the size of a basketball. Imagine tossing hundreds of basketballs out of your window each minute. That’s what poorly designed, unsealed radon systems do.
Just as you can temporarily (or permanently) reduce radon levels in your home by opening windows and doors, so can you with an inefficient radon system. By leaving unsealed floor drains, sumps, and other penetrations you may still reduce your radon; however, careful scrutiny of your year-over-year HVAC utility bill will reveal a hidden, vampire cost of your radon mitigation system.
Sump sizes and penetrations
Sealing a sump lid means creating an airtight seal around all penetrations and edges. Since sumps have biannual maintenance needs, it’s recommended you only use silicone caulking for sealing. Permanent sealants are not recommended.
There are few standards in sump system design. Pit sizes range from about one to two feet in diameter. Shapes can be round, rectangular, or square. For that reason, our lexan lids are the most popular (see here). They consist of a 24” x 24” sheet of ¼” lexan plastic. This plastic is incredibly strong: in our testing it held over 300 lbs while barely bending. Since it’s a square sheet, it allows the contractor or homeowner to cut out penetrations wherever they see fit. This way you can match your exact sump pit and penetration size. If you’d like to see through the lid, choose clear lexan plastic. If you want to save some money, choose grey.
We also carry seals for PVC pipes and wire cord grommets. These sizes are listed on the product pages of our website along with photos. Type “seal”, “gasket”, or “grommet” into our search bar to see available options (less is more with our search bar).
As with everything in our industry, nominal or colloquial dimensions do not match exact dimensions. When we say 4” we mean 4” schedule 40 PVC. ID means inner diameter and OD means outer. It’s best practice to order the grommet you want, but do not make any cuts until you receive your shipment and have measured yourself. Like my Dad always said, “measure twice, cut once”.
Sump Standards
Some parts of the US where sump systems and ground water are more prevalent have standard sump sizes. If you think you might have a standard sump, search “jackel” or click here. Jackel has been making sump lids for many decades and has some very cool designs right out of the box. Jackel lids only work with 3″ PVC, as 3″ Radon piping is more standard in the Eastern US where these lid sizes are common.
Floor Drains and Check Valves
For more information on one way check valves for your window well drains, floor drains, and french daylight drains, please read this article.
As always, be sure to use a certified professional for energy efficiency and safety.
Thank you for reading!
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