CIRS Illness: Understanding What a Water-Damaged Building Is

When we think of water-damaged buildings, we often picture structures with roof leaks or major plumbing failures. However, these visible issues are not the only sources of water infiltration or damage. Understanding the different types of water damage is essential for assessing your home’s condition and evaluating potential property purchases, particularly when considering their impact on health.

For this discussion, I will focus on the architectural styles of the Southeastern United States.

Everything in the red line is part of the envelope. Image credit: GOrate Building Energy Solutions.

A Little About CIRS-WDB

Individuals with Chronic Inflammatory Response Syndrome-Water Damaged Building (CIRS-WDB) are genetically predisposed to persistent and unrelenting activation of their innate immune system when chronically exposed to the ecosystem of a water-damaged building. Approximately 24% of the population carries the genetic susceptibility to develop CIRS-WDB. However, this does not mean that 24% of people have the illness—many may never realize they are vulnerable to the bacteria, molds, and mycoVOCs (volatile organic compounds released from the breakdown of building materials by molds and bacteria) present in WDBs.

Regardless of genetic predisposition, understanding what constitutes a water-damaged building is crucial, as about 5% of those who develop CIRS-WDB do not have the known genetic markers yet still become ill.

The Envelope

The envelope of your home serves as a physical barrier, separating the building's interior from the exterior. It includes windows, doors, the roof, foundation, and walls. A well-sealed envelope prevents outdoor humidity from entering the home or infiltrating the walls. Once a house is built, disrupting this envelope can lead to serious issues. Avoid modifications such as additions, converting attached garages/attics into living spaces, or turning porches and sunrooms into interior rooms. These spaces have prolonged exposure to the external environment and Southern humidity, making them prone to mold and bacterial growth. If incorporated into the home’s interior, these contaminants can spread instantly.

At least once a year—and always after severe weather—inspect your home’s exterior for damage. Look for missing shingles, exposed roofing nails, rotting or mildew-covered soffits, and clogged gutters. Ensure downspouts are intact and direct water away from the foundation, not into crawlspaces or close to the home. Check for damage or gaps around doors, windows, vents, and chimneys. If your attic is unfinished, remember that its floor is also part of the home’s envelope.

Older slab foundations, particularly those built before the 1990s, often lack vapor barriers to prevent moisture from seeping into the porous concrete. For new construction, only the highest-quality vapor barriers should be used. A cracked slab is both a sign of and a pathway for water intrusion.

Inside your home, ensure recessed lighting in ceilings below attics is properly insulated to prevent airflow between floors. Inspect walls and ceilings for water stains or rusting drywall nails, as these indicate moisture issues. Keep in mind that latex paint can conceal significant moisture buildup behind walls.

Attached Garages

Attached garages are not considered part of the home’s envelope, as they function more like outdoor spaces. However, air from the garage can be drawn into the home when using exhaust systems such as dryers, bathroom fans, whole-house fans, and range hoods. To minimize this, the door between the garage and the home should have a tight seal and remain closed as much as possible, especially when exhaust systems are in use.

Crawlspaces

Crawlspaces can lead to several potential problems. Being close to the ground, they provide a pathway for bacteria and fungi from the soil to enter the home, posing potential health risks. The air in crawlspaces is often stagnant and trapped, creating an environment conducive to excessive bacterial and fungal growth. Additionally, most crawlspaces house the home's ductwork, which can develop issues over time.

Flexible fiberglass ductwork, in particular, tends to stretch and sag at strap hangers, forming low points where condensation can accumulate. The fiberglass itself can also serve as a food source for microorganisms. Leaky duct joints and perforations allow contaminated crawlspace air to be drawn into the system, spreading mold and bacteria throughout the home. Unfortunately, homeowners often overlook inspecting their crawlspaces for ductwork defects.

The air near the soil encourages mold and bacterial intrusion, and while plastic vapor barrier sheeting is commonly used, it provides minimal protection against this issue.

Plumbing

A major concern with plumbing leaks is those that occur behind the walls. These leaks are often slow, typically occurring at fittings (T-fittings are prone to pinholes), and may go unnoticed until significant water damage has already occurred. Even purchasing a newer home doesn’t protect you from hidden leaks, as builders may opt for less experienced laborers to cut costs instead of hiring master plumbers.

Refrigerators with water lines are also a common source of problems. If you're planning to go out of town, it's a good idea to turn off your water supply to prevent a leak from going unnoticed. Additionally, regularly check the fixtures and pipes under all sinks for any signs of moisture or leaks.

Humidity

When a home has a humidity level between 62% and 75% or higher, along with a matching temperature, it creates a microenvironment that is ideal for the growth of molds and bacteria. In the Southeast, humidity levels are often 60% or higher year-round, making year-round air conditioning or dehumidification necessary to maintain lower humidity.

Any home that sits vacant for an extended period without electricity or a functioning AC system is likely to experience significant microbial growth, especially on drywall, which is rich in organic material. Problems often arise in homes purchased as second homes, particularly when homeowners from less humid areas are unfamiliar with the climate of the Southeast. In an effort to save money, they may turn off the AC during extended absences. Unfortunately, this can lead to mold growth on walls and throughout the entire home.

Venting

Venting issues in a home can arise when negative pressure causes replacement air to be drawn in through an attached garage, the crawlspace, or areas near the soil. This can lead to unwanted airflow into the home. Additionally, bathroom vents that discharge humid, exhausted air into the attic can result in water damage to the attic over time.

Newer exhaust systems may include make-up air dampers to prevent negative air pressure that can pull garage air into the home. As a simple solution, cracking a window can help balance air pressure, especially when running multiple exhaust systems simultaneously.

Northern Homes (Everything above plus)

In northern climates, one of the biggest concerns in homes and structures is the basement. Basements are subterranean and often prone to water intrusion. Similarly, subterranean structures like partial basements—those built into the side of a hill, where the lowest floor has at least one subterranean wall and the opposite side is often a walkout—can be equally problematic. If a basement has a sump pump, it can become a breeding ground for moisture-loving fungi and bacteria. Additionally, basements tend to be dark and have limited airflow. While a finished basement may seem appealing, it’s not always the best choice.

Basements will continue to pose problems unless the humidity is kept under 50%.

In northern climates, humidity inside the house should not be trapped and typically escapes through the attic. This is different from southern homes, where building codes are designed to prevent outside humidity from entering the home.

Resources:

For an easy-to-follow CIRS House Hunting Guide please visit: https://www.survivingmold.com/resources-for-patients/cirs-house-hunting-guide

For an excellent exercise on understanding building envelopes, visit: https://gorate.com.au/2019/04/16/building-envelope-with-a-red-pen/