My Crawl Space was Fine
Why Now? My crawl space was always fine, so why am I having issues with my crawl space after all these years? You may have lived in your home for 20 or 30 years and never had a moisture problem in the crawl space until now. Why is there a problem if nothing has changed? There is a good chance that something has changed. However, it may not be a glaring change that is obvious. It could be something minor that has created a problem over time. Therefore, it is simply a matter of uncovering the source of your moisture.
Regardless of the age of your home, there are often changes that occur over time that we do not realize have a direct effect on our crawl spaces. In our previous blog, we discussed the history of foundations, specifically the evolution of crawl spaces and the effects the changes have on moisture levels within your crawl space.
There are several issues that can create water and moisture in your crawl space. First, you must identify whether you have a moisture issue or a water issue. Sometimes it is difficult to pinpoint the cause and even more difficult to determine if it is water, moisture, or both! There is a difference between water and moisture issues.
The first step in solving your issues in the crawl space should be addressing water intrusion. Water intrusion in the crawl space may come from one or more sources outside of your home.
Clogged gutters or misdirected downspouts may seem relatively minor, but it can lead to bigger issues. Misdirected water can infiltrate your crawl space. Over time these small changes can lead to issues in the crawl space. Therefore, you may be getting water in a new way that was not previously an issue.
Crawl Space Moisture
Once there is water in the crawl space, you will likely have moisture from the evaporation. This moisture must be addressed. Additionally, if water intrusion is not present and there is still a moisture issue it will need to be addressed before it leads to other issues such as wood rot and mold.
Why Now? Your crawl space may have been fine for years, but now there is moisture. There are some not so obvious changes that may lead to moisture issues over time.
Let’s consider some of the possible factors:
- Vapor barrier deterioration
- HVAC upgrade or ducting leaks
- Setting air conditioner on colder setting
- Shift in ambient temperatures
- Environmental changes
Over time vapor barriers can wear out and begin to deteriorate. Holes and tears in your vapor barrier allow for ground moisture to rise into your crawl space. A new vapor barrier may be needed to help prevent ground moisture from entering the crawl space.
HVAC systems can affect your crawl space. New more energy efficient systems have kept homeowner cost down and the ability to keep the house cooler more affordable. The cooler home results in a cooler crawl space. Furthermore, if HVAC ducting is in the crawl space and has a leak in the ducting, the ducting releases cold air directly into your crawl space. As warm air reaches the cold air from the leaks, condensation can form.
Crawl spaces are constantly evolving to address moisture issues. In the past, crawl spaces were built over the ground and the underside of the floor was exposed to the crawl space. This was before air conditioning and insulation were added to homes. The floor in this scenario was warmer than the ground. When warm air entered the crawl space, it did not condense on the floor because it was warm.
Dr. Joseph Lstiburek discussed these changes in a crawl space during a presentation given to TAREI. Moisture became an issue when we started insulating our floors and adding air conditioning to homes, according to Lstiburek. The wood is now cooler than it was before air conditioning. As warm air enters the crawl space, the exposed floor joists between insulation are susceptible to condensation. This is due to the fact that exposed floor joists are now cold. When warm air reaches the cool floor joists, the air can condense. Why does this matter? Moisture on wood leads to wood rot, mold, and other issues.
Furthermore, as ambient temperatures rise, we are setting our air conditioners cooler and cooler to adapt to the warmer climate. This cooling of the house cools the crawl space and makes it more susceptible to condensation.
Shift in Temperatures
According to the National Oceanic and Atmospheric Administration, the average temperature in recent times is higher than it was in the 20th century. Let’s look at a very simplified version of how an increase in temperature affects your crawl space. There are many factors and theories that contribute to variations in weather. However, for this blog our intent is to simplify and focus on effects on the crawl space and not discuss all the factors and theories that may cause weather and climate change. Our intent is to help you better understand how weather changes over the years affect your crawl space.
Over the last century ambient temperatures have increased. This warmer air can hold more moisture. According to the Clausius Clapeyron relationship, the air can hold 7% more moisture for every 1.8˚F increase in temperature. Therefore, as the temperature increases so does the amount of moisture in the air.
However, there is little change in the actual annual precipitation, however, the intensity of the precipitation at a given time appears to be changing. How does this correlate with crawl space moisture? This extreme precipitation can lead to flooding, higher moisture levels, saturated ground, and erosion. All of which can affect the amount of moisture in your crawl space.
The dew point, relative humidity, and temperature are key indicators as to the moisture level and comfort of the air. The climate change certainly affects more than our comfort level. We feel the effects of weather extremes on our crops, health, building structures and much more.
Changes in Precipitation
The relationship between temperature increases and extreme precipitation is more difficult to track across the globe because it is affected by many factors including the geography and climate. Even within the US, precipitation changes may not have changed as an annual total, but some areas have seen more intense rainfall but less snow or vice versa. This is still important because it changes the seasonality precipitation and amount of precipitation at a given time. Additionally, more intense precipitation may lead to flooding and erosion. These changes affect our structures including our homes.
Changes in the Crawl Space
The increase in air temperature increases the amount of evaporation from water masses increasing the moisture in the air. This excess moisture in the air can result in higher dew points and heavier more intense precipitation. Intense weather affects the level of moisture and water in the ground and soil, water runoff and water tables.
There are many factors that can contribute to moisture issues within your crawl space. Your crawl space was always fine, but relatively minor changes to your home or environment can have an impact. Regular inspections of the area surrounding your home and inside the crawl space can help mitigate issues before a larger issue arises. As we learn to adapt to changes in weather patterns, building practices, and more energy efficient equipment in our homes, we must continue to address the additional moisture and the role it plays in the health of our home.
Now that you understand “Why Now?” . . . “What’s Next?”