Crawlspaces & Ventilation: 10 Fun Facts & Random Observations

1. Inside the living space of a property, proper ventilation is absolutely crucial to the health, safety, and overall comfort of the occupants inside the home.

2.  Standards and guidelines have been established to specify minimum ventilation rates and other measures intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects. More info here:  http://eetd.lbl.gov/ie/viaq/v_rates_1.html

3.  Improving the overall air quality inside a property can be achieved by two methods:

•    Exhausting air contaminants from the building
•    Removing contaminants from the air stream using filtration and/or absorption technologies (i.e. HEPA filtration and activated carbon)

Since most residential properties do not have access to proper filtration or absorption technologies, exhaust ventilation is most practical and commonly used.

4. In addition to improper ventilation, excessive or chronic water intrusion into the property, especially the crawlspace, will contribute to the growth of certain microorganisms.  This can lead to mold infestation impacting Indoor Air Quality, and even more destructive structural damage such as wood decay or dry rot.

5. Water intrusion into the crawlspace will often cause damage to flooring systems (i.e. cupping of hardwood floors, grout separation in tile floors, etc.), wood decay, and oxidation or rusting of metal strapping/hardware.

6. Water enters a crawlspace in either liquid or vapor phase by four moisture transfer mechanisms:

•    Liquid water (i.e. plumbing/sewer leaks, high groundwater table, drainage or exterior flooding)
•    Capillary suction or wicking (i.e. moisture being drawn through concrete footing from saturated exterior soils)
•    High moisture laden air (i.e. elevated humidity from atmospheric conditions entering the crawlspace through vents)
•    Vapor diffusion (i.e. moisture in the vapor phase moving through building materials)

7. Most properties are constructed with vents that are intended to remove moisture from the air in a crawlspace by cross-ventilation.   However, the introduction of moist air from outdoors can actually increase the relative humidity in a crawlspace.

8. Due to stack effect and vapor diffusion, which is a very powerful force, moisture in a crawlspace will seek dry areas.  When moist air comes in contact with  a surface that is colder than the  air, condensation will occur.  Condensation can develop on uninsulated plumbing pipes in the crawlspace, on the underside of a sub-floor, or even the attic roof deck.  Interestingly, many houses with exposed wet soil in a crawlspace also have mold and water damage due to condensation on the underside of the roof deck. 

9. If vapor diffusion from the soil, water intrusion from poor drainage, unmitigated plumbing leaks, or infiltration of moist air exist in a crawlspace, one or more of the following is usually observed:

  •   Surface mold growth, structural damage, and health issues
  •   Termite or other pest infiltration
  •   Accumulation of odors  
  •   Termite or other pest infestation

10.  The best way to mitigate crawlspace moisture is to treat the crawlspace as a conditioned space by (1) insulating walls with foam panels, (2) seal the crawlspace floor and walls with heavy gauge polyethylene or vinyl encapsulation system, with the seams sealed tightly at all edges and overlaps, (3) seal the rim joists with two-part closed cell foam.

Insurance Claims, Contractors, Homeowners: Why Can’t We all Play Nice? Here Are Seven Steps That Can Help…

After a fire or water loss, which can result in mold contamination, the only goal of most homeowners is to have competent and timely restoration that will protect both the indoor air quality as well as the asset value of the property. Similarly, the goals of good contractors are to restore the home, be paid for the services, and have a happy customer. The goals of reputable insurance companies are to restore the home to pre-loss conditions and pay a fair market price for the services. Since these goals are not mutually exclusive, they all can be realized with little or no conflict, right?

Most people who have experienced such losses are probably raising their eyebrows as they whisper, “Yeah right,” to the question. Unfortunately, many factors, including policy exclusions for mold, poor documentation from homeowners, greedy contractors, and overburdened insurance adjustors, can cause conflicts, delays, disappointments, and antagonism during the restoration of a covered water or fire loss.

At times, little can be done by the homeowner to mitigate antagonism if an adjuster takes on a confrontational demeanor from the get go. However, in many cases, proactive measures that begin at the time an insurance policy is purchased empower homeowners to steer an unfortunate loss in a harmonious manner. The following “to do” list for the insured party will go a long way toward making sure that the insurance company, contractors, and homeowners play together in the same sandbox without throwing sand in each other’s eyes.

  1. Understand the insurance policy before purchase. Ask questions about mold riders, sump pump and drain coverage, covered water losses, water damage after fires, smoke and soot damage, odor mitigation, and deductibles.
  2. Research and retain a list of reputable water damage, fire, and mold inspection companies and restoration contractors so that you can be in control of who is hired to do the work.
  3. Have your home inspected by a qualified inspection company that can document conditions relative to water damage and mold before you ever have a loss. This step can prevent claim denials due to poor maintenance or historical damage.
  4. Retain records of prior losses and repairs.
  5. Retain photographs and receipts of furnishings and belongings.
  6. Have realistic expectations regarding repairs.
  7. All documents, including the insurance policy, should be stored in a fireproof safe at home or at another location.

Just like a group of kids in a sandbox, bullies exist on both sides of the fence with insurance losses.  Courtesy, common sense and commitments to doing the right thing are sometimes overshadowed by fear, greed, and hidden agendas. I still believe that it is wise to be prepared and try to play nice before calling in the troops.

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