Published on April 1st, 2015 | by Dawn Killough
9 Keys to Building a Healthy Home
Using the right materials is one step in ensuring good indoor air quality and a healthy home. It also takes a range of building science-based strategies—from proper ventilation and moisture control to radon mitigation and conscientious construction practices–to make sure a home is healthy. Thanks to Brandon Weiss and Evolutionary Home Builders for sharing this list of strategies.
1. Conduct a third-party laboratory certified indoor air quality test. Testing for the indoor air quality by using a professional third-party lab will give you a performance metric to compare and improve homes. Consider testing for formaldehyde, tVOC (total VOCs, or volatile organic compounds), particulates, and mold.
2. Keep air changes to a minimum. Ensure that the home is built to perform at least less than 1.5 ACH@50 Pascal. (Click here for more on air change calculation.) We like to build to the Passive House required .6 AHC@50, but 1.5 is a good goal to shoot for if you are just starting to measure this metric. Having a tighter envelope prevents dust, insects, and airborne particulate from entering the dark, drafty corners of most homes.
3. Provide balanced and distributed energy (or heat) recovery ventilation. Installing a balanced ventilation system with MERV filtration is critical for superior comfort and air quality. This makes certain there is no pressure imbalance in the house. For example, an exhaust-only ventilation plan requires bringing in the makeup air somewhere. If it’s a tight home, you know it’s not evenly distributed or filtered correctly. Additionally, having your ventilation system distributed throughout the home will ensure that fresh air gets to all the places you would want it to, like above your beds.
4. Make sure walls are modeled using the WUFI tool to guarantee proper dry out potential. WUFI is a hydrothermal modeling tool that models your exact building assembly with all of the layers to your exact climate. It runs a multi-year model that shows if there is a risk of condensation in your wall and assesses the potential for mold growth. Condensation within your wall is moisture, and moisture leads to building failure.
5. Install carbon monoxide detectors on every floor and within 15 feet from all bedrooms. An odorless, fatal gas, carbon monoxide is obviously important to monitor in the home, and installing detectors correctly will ensure there is never a dangerous level.
6. Install a radon vent below the basement slab that vents through the roof. A passive radon vent installed through the roof is cheap and easy. Take it a step further and also run in a junction box next to the pipe in the attic in case the homeowner needs or wants to add an exhaust fan to make it an active radon mitigation system.
7. Work to eliminate condensation, which can lead to mold growth. A third of the home’s R-value should be installed outside the air barrier to ensure any condensing surfaces in the wall assembly are eliminated. This is a good rule of thumb for colder climates zones and WUFI is a great tool to double-check that the system is working properly. The exterior insulation will warm the exterior sheathing so that the inside face of the sheathing does not become a condensing surface.
8. Take photos of all wall cavities prior to insulation. Transparency is critical to maintain trust between builder and client, knowing the builder stands firmly behind their product. Taking images reinforces that the builder takes pride in the cleanliness of their homes, and also gives the owner the exact locations of all mechanical systems and studs. This information is key for hanging pictures and for future remodels.
9. Flash exterior penetrations, windows, and roof to help move bulk water away from the home. Unfortunately, American homeowners have become accustomed to leaky windows and roofs, and that needs to change. If exterior water is finding its way into your home, it cannot be considered a healthy home.