Indoor-air quality is a topic of discussion that many builders choose to avoid and rightfully so.
When new, innovative building materials and techniques started being introduced in the 1980’s, most builders jumped on the band wagon and started incorporating some of these products and techniques into their home building projects.
Building science wasn’t a term that most builders were familiar with and no one fully understood how these products and techniques would impact the performance of the homes they were building or of the consequences.
Before long, the problems linked to our lack of understanding came home to roost and we had a mold epidemic on our hands.
And then, the litigation began. Hugh sums of money were being awarded home owners with mold issues.
Mold remediation became big business and we started hearing the term, “mold is gold.”
Next, came the insurance industries answer to the problem.
Insurance companies would no longer cover builders for mold claims filed against them.
Back then and today, the word “mold” carries the same weight as “the plague” for those working in the building industry and should be avoided at all costs.
Mold can have a big impact on indoor-air quality, so it’s easy to understand why builders might shy away from even the mention of indoor-air quality.
If they don’t understand the principles of building science, they don’t know where to begin.
Mold is a fungi, a living organism that requires food, water and certain conditions in order to survive and thrive.
Green building professionals understand how the laws of nature interact with the interior and exterior of the homes they build and know how to deprive mold of what it needs most to survive. Water. Moisture is the main culprit when it comes to mold growth.
Of course, mold needs food and a friendly environment, but water is key.
Two of the three key components to averting mold issues are found at the exterior and interior of the home.
A continuous drainage plane (house wrap) and proper flashing details at the exterior, combined with rain-screens that allow vapor and wind-driven moisture to drain and dry behind exterior siding ensures that moisture will be diverted away from the structure and won’t find its’ way in.
A building envelope that is built tight won’t allow interior moisture vapor into wall cavities and roof assemblies, where mold can thrive.
The third component to avoiding mold issues is proper ventilation.
Proper ventilation is achieved by using quality bath fans that are properly installed. In some instances, whole house ventilation systems are installed.
Air exchangers, knows as Heat Recovery Ventilators (HRV) or Energy Recovery Ventilators (ERV) allow the homeowner to control the humidity level in the home while using the stale heated air that is expelled to temper fresh, incoming air. The result is a complete change of air in the home, about every 4 hours on average.
In cold climates, these units are meant to be run during the heating season.
The colder it is outdoors, the stronger the vapor drive inside the home.
Warm moisture vapor is drawn to air leaks in the building envelope and cold surfaces, such as windows, where it will condense back to bulk water form and start to promote rot and mold growth.
Mold growth is just one contributing factor to indoor-air quality and an important one to know how to avoid.
There are other risks associated with indoor-air quality, such as Radon gas and off-gassing from building products, such as cabinetry, carpeting and fossil fuel appliances.
We’ll address how best to manage these risks in upcoming posts, so please, stay tuned.
If you’re interested in building a high-performance home that will provide a safe, healthy indoor environment or would like to learn more about indoor-air quality, contact Great Lakes Carpentry today.