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hvac condensation - Specialty Foundation Repair

Crawl Space Humidity

We’ve been getting increased amount of inquiries about what the ideal humidity level is inside the crawlspace. This is a great question with many varying opinions. Some good, some bad, and some really bad. Unfortunately, this confuses the issue and has allowed for the development of a multi-billion dollar problematic boom of predatory sales driven franchising to manifest inside the market. And the public in return pays the price with poor diagnosis, embellishment of symptoms, and a general malaise of linear thinking when getting repair estimates from contractors.

Crawl Space Health Factors

The fact of the matter is, relative humidity is just one of the many factors needed to be taken into account when properly diagnosing crawlspace health. Temperature, dew point, and equilibrium wood moisture content must also be considered. A few days or even weeks of elevated relative humidity levels inside crawl spaces DOES NOT necessarily translate into immediate crawlspace condensation and wood moisture problems. It is all a factor of dew point or reaching 100% saturation of the particular air mass trapped inside the crawlspace. Once the environment reaches 100% RH condensation forms and the wood framing members absorb that moisture causing rapid expansion of the wood framing members and the development of biofilm contaminants on the outer layers of the wood. Excess moisture builds up inside crawlspaces over large periods of time. The tighter the crawlspace, the less air movement available with a more cumulative, and extreme moisture dynamic developing. Ductwork inside crawlspaces also creates dead pockets and microclimates combined with localized dew point challenges as the duct work itself works like a refrigerator coil. Old metal duct work in place is even more problematic as older systems tend to leak cold air into the crawlspace environment during the summer months lowering the dew point slightly and creating more condensation build up on duct work and framing members.

The Atmox System

Managing the buildup of moisture can be resolved by either improving ventilation with a hybrid dewpoint-controlled fan system combined with dehumidification such as the ATMOX System, visit at and/or sealing up the crawlspace with a traditional encapsulation combined with dehumidification. Every house is a little bit different than the next, and the phenomenon changes in different regions of the country. There is never a one size fits all magic answer when developing solutions to these challenges. Ever. Each situation must be evaluated on a case by case basis by an experienced, independent professional. Wood moisture readings should be under 19% at all times. For an interactive table of values you may visit this website at and utilize their tables, charts, and calculators to help you understand how the science works for your particular area.  

For specific questions, concerns, and/or breakdown of potential solutions please don’t hesitate to contact us directly. We are here to help!!


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