We often get calls from DIYers that think they’ve invented a fresh new way of doing radon systems. Sometimes they think they’ve broken an industry-conspiracy and are excited to share it. Crawlspace ventilation is one of these calls.
We recommend traditional radon systems usually for one of the following reasons*: they solve the radon problem 365 days of the year; they solve the radon problem in all weather conditions and climates; they reduce risk of reentrainment of radon back into the home; they are the most energy efficient method; they do not negatively affect another part of the home like backdrafting appliances or increasing mold/moisture risk.
Crawlspace ventilation risks most of these possibilities.
First, if the subfloor is not insulated then ventilation is essentially like opening the windows of your home. Opening windows can reduce radon levels temporarily, but it is not a long term solution. Radon levels are highest on the coldest days of the year, the exact days you’d like to keep your windows closed (read more about the stack effect here).
If the subfloor is insulated, you may also risk bringing unwanted moisture or condensation into the crawlspace, which also increases the mold risk.
High winds or oversized fans can risk back-drafting furnaces or other appliances in the crawlspace itself.
Sub-membrane depressurization systems, like all good radon systems, negate the pressure plane of the home and effectively increase the barrier of soil air to conditioned air. It short circuits the stack effect and keeps outside air and soil air where it should be: outside the thermal envelope of the home**. It does not risk conditioned air to do this, and thus is the most energy efficient way of mitigating radon risk. Read more about how properly designed crawlspace radon systems reduce moisture and the smells that come with it here.
Drier soils, lower HVAC bills, and most importantly: low radon risk. Choose traditional crawlspace radon systems and be safe!
Thank you for reading!
*The main reason we recommend sticking to traditional systems is that ANSI/AARST Radon Standards have been peer reviewed over three decades by thousands of professionals. They are the most comprehensive and up-to-date standards we have. Many, many volunteer hours have gone into them, so next time you see a certified radon pro: thank them.
** “Your home sucks” is a joke you may hear at a radon training course. What we mean is warm conditioned air—in homes without RRNC systems–actively pull soil air into the home. It’s called the stack effect. When you build a radon system, you negate this effect. If you’ve ever had an issue finishing your soda or milkshake from a hole in the straw, you’ve had a real world example of when a pressure system is negated. (RRNC means radon ready new construction, more here)
