This time of the year, I get a lot of calls from homeowners who are flummoxed over issues related to poorly insulated homes, high energy bills and uncomfortable living conditions. One call that I received was from a homeowner who had water condensing and ice on his roof sheathing in the attic. Unfortunately, this isn’t uncommon.
The homeowner had already taken the advice of a contractor who suggested he change the attic ventilation from existing open gables to eaves and a ridge vent. He went along with this and paid to have it done. The homeowner had already treated the attic for mold. Additionally, Mass Save performed an audit and had crews do targeted air sealing and add insulation on the attic floor. An attic hatch cover was added. The condensation persisted, and the homeowner saw no decrease in his heating bill from the prior year for the same period.
A blower door test and infrared scan quickly revealed the source of the moisture problem. While the house was depressurized, infrared showed points of air leakage in the ceiling below the attic. Eight recessed lights directly over the kitchen and right around the corner from a bathroom were open to the attic. Also, the attic hatch cover was not completely sealed to the floor, allowing air to pass under it as seen with the infrared. A family generates plenty of moisture, which in this case was going straight into their cold attic.
Another situation that was a contributing factor to the homeowner having no observable savings was the cold air feeding into the edge of the attic insulation (called wind washing). The wind washing was revealed by testing, easily discernible from the ceiling below using infrared. The eave vents that were installed did not have an air barrier (an eave baffle) to send outside air above the insulation, instead of through it.
The solution for this homeowner is to take care of the details that others missed. He must ensure the recessed lights do not allow air to convect into the attic. The best options are either replacement with Insulation Contact Air-Tight (ICAT) fixtures that are sealed with caulking between the fixture and the dry wall or placing air-tight (and fire-grade) boxes over the lights, as long as there is a 3-inch gap between the fixtures and the boxes. A third option is to remove the lights and close off the holes with dry wall. The attic hatch needs to have more weather strip added so that it seals to the floor.
The last observable contributor to the lack of savings was an air gap left between the fiberglass and the dry wall that was hanging on strapping. This was caused when the insulation contractor simply blew the loose-fill cellulose over the existing fiberglass batt insulation, resulting in less effective insulation and unachieved savings. Infrared showed plenty of purple (cold air) circulating just above the ceiling. It is best to blow the loose-fill insulation over and under the fiberglass insulation so as to have a thick thermal blanket with no gaps. Overall the current insulation job is like wearing a winter coat — unzipped.
So, it’s those pesky details that can be very costly if not addressed. Hopefully, knowing the source of attic problems will allow homeowners and contractors to do the right things — right.
Tim Gould is the director of Informed Energy Solutions, Inc., located in Amesbury. Contact him at 978-388-6349. On the web at www.InformedNRG.com.