The LEED pre-drywall inspection for Bethesda Bungalows’ KellyGreen house under construction in Chevy Chase, Md., clocked in at just over four hours—probably a bit longer than most in attendance had anticipated. But a lengthy meeting isn’t necessarily out of the ordinary for a green project (green rater Andrea Foss comes to inspections prepared to stay as long as necessary to identify and remedy whatever challenges arise), and what the inspection at this house found during a routine duct-leakage evaluation further emphasized why the builder has made LEED and other third-party green programs standard practice. The purpose of the LEED pre-drywall inspection is to go through the items on the Energy Star Thermal Bypass Checklist, verify completion of LEED checklist items behind the walls, and spot any other potential problems.
Foss, managing partner with EverydayGreen in Washington, D.C., began by inspecting KellyGreen’s air sealing and insulation, including measuring the thickness of the spray foam. She pointed out areas where gaps or voids needed to be filled, and Bethesda Bungalows project manager Ryan Schulte had a crew member fix them on the spot. Schulte also had arranged to have his insulation trades on standby and brought them in to beef up the foam insulation around the garage interior walls at Foss’ request.
Raters also look for LEED prerequisites or items the builder wants to obtain points for, such as insulated pipes.
The biggest challenge at the KellyGreen inspection came during the duct-blaster test. Though not required for LEED certification, Foss highly recommends the test to her clients and Bethesda Bungalows conducts them for all its green-built homes. “Now’s the time that you need to find it,” Foss says, noting that leaks are much more costly and time-intensive to fix later.
KellyGreen’s initial readings showed an unexpected 610-cfm leakage rate--13% of the square footage--or about $325 in wasted energy dollars a year. (Ideally, homes have duct leakage of less than 5% of the square footage, according to Southface Energy, but many traditionally built houses have upwards of 15%.) The team searched the ducts, sealed registers, and connection points visually and eventually employed a fog machine to help locate the problem spots. They found one leak at a metal-to-flex connection, where an installer had used insulation alone instead of Mastic.
Another source was an unsealed connection at the energy recovery ventilator, which Foss says is a fairly common problem because some subs don’t think of the ERV as part of the ductwork. In addition to inefficiencies, this can contribute to poorer indoor air quality if not fixed.
The third leakage point was harder to spot: Poorly sealed connection points along the top of a duct run in the basement, a hard-to-reach area that is another common failure point. Schulte contacted the HVAC contractor to come out the next day to re-Mastic those areas and fix the other two items.
The results, and the simple remedies, from the duct blaster test provided further support for performance testing in homes and for Bethesda Bungalows’ decision a few years ago to make them standard practice. They also emphasize the ongoing need all builders face in educating subcontractors on, and holding them accountable for, high-performance installation.
“I can’t emphasize enough that ductwork is the No. 1 problem that builders consistently struggle with,” says Foss. One resource she recommends is this online tutorial.
To help clients prepare for the pre-drywall meeting, Foss sends them a list of what she will be looking for and requests that all items on the Thermal Bypass Checklist be completed beforehand. Being prepared and having subs at-the-ready helped Schulte address problems quickly so that there was no delay in drywall installation.
Schulte reports that the inspection process, though never the same nor without some unanticipated challenges, has gotten easier with each green home. “We’ve incorporated these practices into our standards,” he says.
Katy Tomasulo is Deputy Editor of EcoHome.