GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

radon mitigation via sealing the sump only

prometheanfire | Posted in Mechanicals on

Hi,  I have a bit of radon coming though the basement.  Measured between 4-8pci (averaging at 6).  I’d like to start with the least invasive method of mitigation, meaning sealing the sump and other openings in the slab (cracks and a cutout for a shower (that will be sealed with a sump cover blank).  This means no ventilation (I’ll ventilate if this isn’t enough).

My question is, do I need ‘make-up-air’ for the sump, (as it’s pumping water out, so will be depressurizing the sump pit and associated drain tile)?

My gut says no, since the volume of air is high enough, and air will still get in via whatever means.

A second question, can both a tankless gas water heater and gas furnace be supplied via a single duct from the outside? (cross sectional area would be the same (two 3 inch to a 4 or 5 inch, or something.)  I do plan on replacing with energy/green options eventually, but didn’t get much choice with where I’m starting.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. prometheanfire | | #1

    This seems to be working (sealing sump and some cracks only, have gone from 8pCi/L to 1pCi/L over the last month. That said, the snow on the ground has disappeared, and that probably has something to do with it as well. I have more cracks to seal (a couple hundred feed of it...), once that's done by next winter I hope to keep those levels low.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |