Tag Archives: crawl space

Mold in a Crawl Space

This is a slightly revised re-post from our very popular June 2012 blog about mold in crawl spaces.

Summer is almost here, and with the warm temperatures comes more homeowner activity in the yard. A few will even open the door to their crawl space and peak inside. What happens if you find a bunch of mold that seems to be growing on the wooden floor joists under your house?

First, understand that a few different kinds of things that look like mold can also stick to joists. Second, understand that some mold on the wood under your house is normal and to be expected, especially if your crawl space is an ‘open’ design with foundation vents that allow outdoor air into the space. Some mold under the house may be defined as ‘normal fungal ecology’, especially in the southeastern U.S.

If you are reasonably sure that your floor system has mold on it and want to know if something needs to be addressed, you may want to consult with an expert, or be prepared to buy a few measurement tools and learn how to use them. An expert is best defined in this case as someone who can assess the crawl space without bias (i.e., they do not sell sealed crawl systems or perform mold remediation).

The optimal time of year for an expert opinion of a crawl is during summer months. This allows the expert to view the crawl when mold is most active, outdoor humidity levels are up and when the house is using air-conditioning.
Here are the steps your expert should take:

  1. While wearing protective gear, crawl through the entire underside of the house and document conditions with photos of the vapor barrier, foundation walls, floor insulation, joists/sub-floor, and any mechanical equipment (especially air handler & ductwork;
  2. Collect wood moisture measurements of several joists and the sub-floor, especially near plumbing penetrations and near the foundation if moisture is observed;
  3. Check the vapor barrier for tears or gaps that could allow soil moisture to evaporate onto the floor system;
  4. Measure soil moisture content if it appears to be damp. Note if all the soil is damp or just certain areas;
  5. Note any strong musty odor. A crawl space should smell earthy, not musty;
  6. Note any debris such as old pipes, insulation or ductwork lying on the floor. These should be cleaned out;
  7. Warn the homeowner of the danger of storing gasoline-powered yard tools under the house, especially if they are near a gas-fired furnace (we have seen this hazard all too often);
  8. Observe the level of air movement through the crawl space. We often find a ‘dead zone’ near the center of larger crawls, which is usually home to more than the typical amount of fungal growth.

Your expert should be able to provide a report that includes a list of observations & recommendations. Here comes the tricky part – how do you know if the mold in the crawl space is at a normal level and is unlikely to harm the family living in the house?

This is where experience plays a large role. Someone who is new to crawl space inspections may miss something important, make a big deal out of something insignificant, or not know how to communicate their findings very well. Other variables that come into play are the tightness of the duct system under the house, the number of occupants who are sensitized to mold and  claim to be experiencing health effects, and the air quality inside the home. It is important to understand that bacteria or mold in a crawl space will find their way into a house through gaps in the floor system and HVAC components and on thermal air currents that naturally travel upward from the crawl to the attic. An expert should be able to measure the likely impact of mold on your indoor environment or be able to direct you to someone who can.

A final note about the collection of samples from suspect mold in the crawl space. It is not always necessary to know the exact level or species of mold (information lab analysis will provide), however, sample collection is often useful, especially if someone in the home suspects a health issue that could be related. Ask your expert to explain their sampling method and what information they hope to gain by sending a sample into a lab for analysis. An experienced individual will be able to clearly explain why sampling is necessary and how it will guide the process of determining if the crawl space has a normal fungal ecology.

Landlords and Tenants – Tips for When Indoor Air Quality is an Issue (Part 2)

Craig Whittaker founded Environmental Solutions Group to help property owners more appropriately contend with environmental health and safety issues. ESG has helped dozens of landlords and tenants sort through air quality issues and reach a fair conclusion.

Our office fields several calls each month from either a landlord or tenant concerning the air quality in a rental unit.  We tend to get more calls from tenants than from landlords, usually due to a child being sick most of the time or visible mold on tile grout or window sills.

The landlord/tenant challenge is often more of a battle as both sides believe they are right.  Here are a few suggestions for landlords when there is an issue. We covered tips for tenants in a previous post.

Tenants often blame any indoor air qualities on the property itself and not their lifestyle. As the property owner, do your part by taking proper care of the building. This should include visiting your property a few times a year to see how the tenant lives and work on any changes before there is a major issue.

Visit the property on a rainy day to be sure rainwater is not ponding near the foundation or getting under the house. You can check the gutters and downspouts for proper drainage as well. A damp basement or crawl space can lead to health symptoms for people living in the house and will eventually cause structural damage.

Fix any leaks promptly and let the tenant know when you find and/or fix a leak. This includes keeping evaporative moisture from the soil under a properly installed vapor barrier in the crawl space and cleaning out gutters so they drain properly.

If the lease specifies no smoking indoors and no pets, enforce the rules at the first sign that the tenant is smoking indoors or has brought home a pet.

Document any issues that could affect air quality with photographs and a written timeline of when the issue first appeared.

Mold in Your Crawl Space – How Much is Too Much?

Summer is almost here, and with the warm temperatures comes more homeowner activity in the yard. A few will even open the door to their crawl space and peak inside. What happens if you find a bunch of stuff that seems to be growing on the wooden floor joists under your house?

First, understand that a few different kinds of things that look like mold can also stick to joists – namely insect feces. Second, understand that some mold on the wood holding up your house is normal and to be expected, especially if your crawl space is an ‘open’ design with foundation vents that allow outdoor air into the space. Some mold under the house may be defined as ‘normal fungal ecology’.

If you are reasonably sure that your floor system has mold on it and want to know if something needs to be addressed, you may want to consult with an expert, or be prepared to buy a few measurement tools and learn how to use them. An expert is best defined in this case as someone who can assess the crawl space without bias (i.e., they do not sell sealed crawl systems or perform mold remediation). 

The best time of year for an expert opinion of a crawl is during summer months. This allows the expert to view the crawl when mold is most active and when the house is using air-conditioning.
Here are the steps your expert should take:

 

  1. While wearing protective gear, crawl through the entire underside of the house and document conditions with photos of the vapor barrier, foundation walls, floor insulation, joists/sub-floor, and any mechanical equipment (especially air handler & ductwork;
  2. Collect wood moisture measurements of several joists and the sub-floor, especially near plumbing penetrations and near the foundation if moisture is observed;
  3. Check the vapor barrier for tears or gaps that could allow soil moisture to evaporate onto the floor system;
  4. Measure soil moisture content if it appears to be damp. Note if all the soil is damp or just certain areas;
  5. Note any strong musty odor. A crawl space should smell earthy, not musty;
  6. Note any debris such as old pipes, insulation or ductwork lying on the floor. These should be cleaned out;
  7. Warn the homeowner of the danger of storing gasoline-powered yard tools under the house should you see any of these devices, especially if they are near a gas-fired furnace (we have seen this more often than you might believe);
  8. Observe the level of air movement through the crawl space. We often find a dead zone near the center of larger crawls, which is usually home to more than the typical amount of fungal growth.

Your expert should be able to provide a report that includes a list of observations & recommendations. Here comes the tricky part – how do you know if the mold in the crawl space is at a normal level and is unlikely to harm the family living in the house?

This is where experience plays a large role. Someone who is new to crawl space inspections may miss something important, make a big deal out of something insignificant, or not know how to communicate their findings very well. Other variables that come into play are the tightness of the duct system under the house, the number of occupants who are sensitized to mold and are claim to be experiencing health effects, and the air quality inside the home. An expert should be able to address all of these variables or be able to direct you to someone who can.

A final note about the collection of samples from suspect mold in the crawl space. It is not always necessary to know the exact level or species of mold (information lab analysis will provide), however, sample collection is often useful. Ask your expert to explain their sampling method and what information they hope to gain by sending a sample into a lab for analysis. An experienced individual will be able to clearly explain why sampling is necessary and how it will guide the process of determining if the crawl space has a normal fungal ecology.