Did you know that about 20 billion board feet of wood is destroyed in the US each year? That’s more wood that is damaged each year than by fire! The wood that is used to repair this damage each year makes up almost 10% of the annual wood production in the United States alone…. that’s a lot of wood! It also costs homeowners billions of dollars in treatment and repair costs each year.  This damage is mostly caused by water damage and fungus. It is important to be proactive when it comes to preventing damage from fungus. By catching it early you can not only treat it easier but also save yourself a significant amount of money.


Fungus can develop when wood and moisture come together. There are two main types of fungus that can develop in your crawlspace:

  • White fungus – which is caused when wood is consistently wet (e.g. from standing water or leaky pipes)
  • Brown fungus – which thrives in humid environments (especially here in the Southeast)

There are four conditions fungus needs in order to grow:

  • Spores – which are found everywhere, even in the air we breathe.
  • Temperature – fungus likes the same temperatures us humans do, and even some colder temperatures as well.
  • Food – Fungus need an organic food source to thrive, and especially like cellulose which is found in wood.
  • Moisture – Fungus need a relative humidity of at least 70% or greater to thrive, which is very common in the Southeast.


  • Health – Fungus can pose a threat to humans, especially to those with respiratory illnesses like asthma and allergies. Breathing in spores can make you sick.
  • Home – Fungus develops from wet wood and can compromise the structural integrity of your home. It weakens the wood which can cause it to bend and break.
  • Money – The structural damage caused by fungus can lead to costly repairs for your home.


There are 3 main causes of fungus in your crawlspace:

  • Standing Water: Standing water, or bulk water, in your crawlspace can be caused by a drainage problem, flooding, or a plumbing leak.
  • Ground Evaporation: The soil around your crawlspace evaporates moisture into the air, which then condenses in the cooler air of the crawlspace. The foundation walls can also evaporate moisture into the air.
  • Outdoor Air: Outdoor air which is high in moisture can come into your crawlspace through vents. This moisture rich air increases the relative humidity of the air in your crawlspace, leading to more moisture.


So now that you’ve identified crawlspace fungi and how it grows, what can you do to prevent it? Check out these five tips to prevent and treat fungus in your crawlspace.

  1. Check The Humidity. Measuring the humidity in your crawlspace can let you know if the percentage is high enough to foster fungal growth and allow you to take steps necessary to prevent it. You can install a digital thermo-hygrometer with a remote sensor to check the humidity in your crawlspace.
  2. Remove The Moisture. You can check the crawlspace yourself; or, if you aren’t able or comfortable enough to do it yourself, you can have a professional moisture inspection done. This will help you identify the source of the moisture problem (a leaky pipe, a drainage issue, etc) and take the appropriate steps to fix it.
  3. Borate Treatments: Borate treatments can soak into the affected wood and prevent any fungus from returning.
  4. Wood Treatment/Repair: If the wood is not significantly damaged, you can use wood treatments that will strengthen and repair your existing wood. If the damage is significant, you may have to replace the affected wood and then treat to prevent recurrence.
  5. Crawlspace Enclosure: Consider a complete crawlspace enclosure. Crawlspace enclosure helps eliminate moisture, increases energy efficiency in your home (with up to 18% savings on your energy bills), helps control pests, and helps improve the overall health of your home.