Last week we published this photo as part of our “What’s Wrong With This Picture?” series. The photo shows a substandard fiberglass insulation job that was representative of an entire residential subdivision that hoped to qualify for Energy Star. Examples like this show that quality control by HERS raters is a weak link in the Energy Star program.
To comply with Version 3 of the Energy Star [no-glossary]Homes[/no-glossary] specification, a home must meet the requirements of the Thermal Enclosure System Checklist. Moreover, Version 3 specifications require cavity insulation to be installed to meet the Grade I installation standard developed by RESNET. According to the Grade I standard, insulation must be installed without gaps or flaws, filling the cavity from side to side and top to bottom, and with less than 2% of the insulated area showing signs of insulation compression. The standard required insulation to be split or fitted tightly around wiring, electrical boxes, and other services in the cavity.
Issue 1: The insulation does not fill the cavities, back-to-front
If you look at the lower left-hand corner of the photo, you can see that the batt doesn’t extend from right to left to fill the whole cavity.
Achieving the Grade 1 standard with fiberglass batts is difficult. However, the standard is clear: insulation must fill the cavity completely, from side to side, from top to bottom, and from front to back.
Installing Fiberglass RightThe Energy Star Homes Program Raises the Bar with Version 3
Issue 2: The insulation is tucked behind pipes and wiring
No attempt was made to split the insulation around obstructions.
The insulation must be split or cut so that it fits tightly around pipes, wiring and other services in the cavity.
Issue 3: The insulation is not cut out around the electrical boxes
These installers were clearly in a hurry.
The insulation must be cut so that it fits tightly around and behind electrical boxes, without any gaps.
Issue 4: There is no air barrier behind the tub
Before this tub platform was framed, someone should have installed a durable air barrier on the interior side of the insulation.
Walls behind showers and tubs, once correctly insulated, must be backed with an air barrier — for example, Thermoply — to prevent insulation from sagging and to create a continuous air barrier. All seams, gaps and holes in the air barrier must be sealed.