When a homeowner discovered mold in the attic of their two-year-old home, they called in a professional to take a look. However, after hearing the proposed solution, they remained unsure whether the suggested fix would fully resolve their problem.
Looking for advice, the homeowner turned to the internet for help.
Here's what to know
The discussion began in a post on Reddit's r/hvacadvice, where the homeowner explained their situation.
"We have a new house less than 2 years old," the original poster wrote. "The heat pump is connected to an air handler and ductwork that supplies the house. The attic has spray foam applied to the underside of the roof so the air handler and ductwork sits inside the attic space that is inside the envelope. The attic has no air supply right now."
Despite the home being almost brand new, the OP discovered "mold growth on the mastic where the air handler meets the supply ductwork."
When the homeowner called a company out to give them a quote, the company proposed installing a "4 inch takeoff with boot and grate."
Unsure if this would resolve their mold problem, the OP asked Redditors for their thoughts.
"What's the right fix for a coastal Carolina house?" they asked.
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Many replies treated the mold as a sign of condensation rather than a problem with the mastic itself.
"Mold doesn't just appear when the conditions are right for a short amount of time," wrote one commenter.
Others explained that a sealed attic can still trap enough moisture for cold duct surfaces to sweat if the area is not properly conditioned or dehumidified.
"Dehumidifier," answered one user succinctly.
"And better insulation in areas that condensation is appearing," added another.
Despite the challenges that the OP was facing with their attic-based HVAC, upgrading heating and cooling can still be one of the best ways to save money on utility bills and protect against rising energy prices.
Palmetto can help homeowners understand their HVAC options and reduce their energy bills with newer, more efficient HVACs and heat pumps, and Palmetto's Comfort Plan network can connect readers with vetted installers and heating and cooling solutions for their home.
Other solutions
Another potential solution mentioned in the comments was for the OP to install a small supply vent, though opinions differed on whether this alone would do the job. Some commenters said adding supplies and returns could make the spray-foamed attic function as conditioned space, while others warned that in spring and fall, an air conditioner may not run often enough to remove the humidity that was feeding the mold.
The most common advice was to deal with the moisture in the attic space directly. While some commenters focused on removing the existing moisture by using a dehumidifier, others recommended identifying potential sources of moisture and addressing those.
Commenters mentioned checking whether bathroom fans or cooking exhaust might be venting into the attic, using a blower door test to confirm the envelope is performing as expected, and measuring duct surface temperatures while the AC is running to see whether those surfaces are dropping below the dew point.
If a homeowner decides to invest in an entirely new, upgraded HVAC system rather than piecemeal repairs, the Palmetto Comfort Plan includes $0-down options that can lower heating and cooling costs by up to 50%, and Palmetto Comfort Plans include 12 years of free maintenance.
To drive their utility costs even lower, homeowners can also pair solar panels with electric appliances, including an efficient HVAC system. EnergySage makes it easy to compare solar options and find the best solar setup and installer for a home and budget, and it can help homeowners save up to $10,000.
Where can I learn more?
Mold and HVAC headaches like the OP's have shown up in a lot of different ways, especially in hot, humid homes.
• Across the Southern U.S., a widespread mold threat has left homeowners fearing for their health.
• A tenant found mold in an AC unit and said the landlord ignored the problem.
• A homeowner in a 30-year-old house pulled a vent cover and found decades of dust.
• Florida HVAC pros called a viral AC saver a hard pass for humid homes.
• A window unit's blinking red light pointed to a simple air-filter fix.
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