Stop Sweating It! 6 Myths About Indoor Air Humidity Issues DE-BUNKED
- Metal Roofing Alliance
- 1 day ago
- 4 min read
Key Points:
Experts share reasons why you may have an indoor air humidity issues and ways to address the problem.
Roofs, when properly installed with adequate ventilation, help homes "breathe" and keep indoor air balanced.
Not addressing high humidity inside a home can lead to problems and cause harmful mold and mildew.
Does your home have perspiration problems? Especially in areas of high humidity, feeling damp and sticky inside your home is a sign of potentially serious problems that may start right at the rooftop.
Experts at the MRA say these are the most common myths about indoor humidity issues and the truth about how to address them:
Myth #1: Moist indoor air is mostly caused by high outside humidity levels.
Truth: While high summertime humidity can certainly contribute to your home feeling sticky and damp, moist interior air is mainly caused by typical household activities that generate condensation, along with lack of proper ventilation. That includes doing laundry, bathing, and cooking.
Today’s tightly built homes don’t breathe as much—which has weatherization and energy efficiency benefits—and that may lead to condensation issues. Moisture that once escaped through the walls and windows of older homes now may get trapped or wind up in the attic, leading to problems like mold if not addressed through good ventilation. If your walls, windows or sills feel moist or shows condensation issues and drips without obvious plumbing leaks or problems, you may have an indoor humidity problem on your hands.
Myth #2: An airtight attic is the best way to prevent dampness and increase energy efficiency.
Truth: Proper ventilation in the attic space is vital to keep moist air from being trapped and insulation must be kept dry and fluffy to effectively do its job. Studies show that for every one percent increase in insulation moisture, there’s a loss of up to 2.5 percent of insulation R-value. Inadequate ventilation can cause higher energy bills in summer and can lead to ice dams in the winter.
To control attic moisture and condensation, roof ventilation should follow building science: soffit vents typically act as intake vents, with air exhausted out of the top. As a rule of thumb, ventilation should be a 50/50 split between intake (usually soffits) and exhaust (typically near the roof ridge) with enough vents to effectively balance the overall cubic feet of air space.
Experts like Todd Miller, president of Isaiah Industries and MRA’s board of directors, say a quality metal roof is designed to naturally minimize heat gain into the attic, while proper ventilation will allow any gained heat to be released to help increase energy efficiency. Ask your installer what methods they are using to ensure that your new roof has proper ventilation systems incorporated. Needed rooftop ventilation adjustments are much easier to address during installation vs. trying to correct later.
Myth #3: Metal roofs cause more condensation as compared to other options.
Truth: Metal is non-porous, transmits heat and cold quickly, and is generally cool. When moist, warmer air contacts the metal roof, it can cause condensation to be more noticeable. However, when properly installed, metal roofs do not cause more interior moisture problems than any other roofing type.
Best practices include installing a metal roof over good quality decking and paying attention to details such as thermal break, which simply refers to allowing for enough airspace between the metal material and roof decking. Some metal roofing styles such as metal tiles have air space already incorporated as part of their design, helping prevent condensation.
Myth #4: It’s a good idea to allow interior moisture to escape through the ceiling.
Truth: While ventilation in the attic is essential, preventing moist air from escaping through a ceiling in the first place also is key. Consider using a vaper barrier between the ceiling and attic space to prevent moisture from rising. Even using an oil-based paint for the ceiling can be a decent barrier. Seal all ceiling penetrations such as around canned lights. Use ceiling fans and run an A/C fan to circulate interior air and make use of room de-humidifiers. Make sure exhaust fans for bathrooms, kitchens and laundry areas are moving air effectively directly outdoors, not into the attic or the home’s interior.
Myth #5: When it comes to exhausting indoor air, the more the better.
Truth: As much as ventilation is critical, an imbalanced system also can cause issues. Too much exhaust without enough intake leaves a home starved for air, working backwards by drawing in unconditioned outside air and trapping moisture, potentially causing leaks and damp insulation. Likewise, too much intake may lead to cracked or collapsed ceilings in the event of severe winds and air pressure when air rushes in but can’t get out.
Myth #6: Unless I see a mold problem, it’s hard to tell if there’s too much moisture inside my house.
Truth: Your contractor or roofing pro can check the moisture levels using a protimeter, a moisture meter device that checks the moisture level in the wood and insulation. Up to 10 percent of moisture is typical, and anything above that is a concern for condensation problems and organic growth issues. Also check living spaces for mold and high moisture levels. Use your nose as a guide and look in closets, behind furniture, the basement, and crawlspaces if you suspect a problem.
