Healthy Crawl Space, Healthy Home

by | Jul 31, 2020 | Mold Removal

It’s summertime in North Carolina, which means two things: you can easily break a sweat before 9am, and we are receiving calls every day for mold inspections! Usually, when a client calls and says they have signs of mold growth, our investigation begins in the crawl space. In this blog, we’ll give you some pro tips to prevent mold growth in your crawl space and in your home. Remember, a healthy crawl space equals a healthy home!

In Raleigh, the average August temperature is 88 degrees and the average August humidity is 77.9%. If we know that relative humidity in excess of 55% creates favorable conditions for mold growth, it’s no wonder that so many people experience issues during our summer months.

We know that our HVAC systems are working overtime now, but it should be evident when the system is no longer cooling efficiently. Leaky ducts could be the source of inefficient cooling and the reason that mold growth occurs in the property.

How do you know your ductwork is leaky?

Indicators of leaky ducts include:

  • Water on the registers, or rust and discoloration around the registers.
  • A damp dirt odor in the home. Basically, it would smell like a crawl space.
  • Higher than usual energy bills due to inefficient cooling.
  • Standing water in the crawl space.
  • Droopy or wet insulation in the crawl space.
  • Tape hanging off of the ductwork in the crawl space.

How do leaky ducts cause mold growth?

Let’s start with the basics: the average lifespan of an HVAC unit is 12-20 years, while the average lifespan of ductwork is 20-25 years. These numbers tell us that if you replace the unit, you should consider replacing the ductwork at the same time. 

Improperly sealed ductwork is often the root problem found during a crawl space evaluation. Cool air escaping from ductwork can cause condensation, which then increases the humidity level in the crawl space. The ductwork distributes this excessive moisture (condensation) from the unconditioned space (crawl space) into the conditioned space (the home).

The problem continually gets worse as the system runs by creating wet building materials inside the insulation of the ductwork and around the registers in the home. When the condensation comes out of the registers it can then collect at the subfloor or on the ceiling. Wet building materials combined with dirt, dust and elevated humidity levels can amplify microbial growth.

In extreme cases, when left untreated, these conditions can lead to rotten floor joists and extensive and expensive repairs. It’s best to perform preventative maintenance now to avoid problems later.

How can you prevent mold growth?

Surprisingly, creating natural air flow is usually all that’s required to prevent crawl space issues. This means not blocking your crawl space vents with landscaping. Creating positive drainage to make water flow away from the house is a must-do. Check your gutters frequently to ensure they are not clogged with debris.

Vapor barriers, sump pumps, ventilation fans and dehumidifiers can help mitigate moisture in crawl spaces. Performing regular maintenance on your HVAC unit is recommended. Have the technician check the seal on your ductwork as part of the service. And finally, don’t forget to look under your house regularly. A visual inspection twice a year can prevent costly issues down the road. Make it part of your seasonal home maintenance routine – when you change your smoke detector batteries, look under your house.

If you see or smell indicators that you may have microbial growth, call PHC Restoration. To learn more, visit