2,080. That was the number on the blower door gauge Wednesday afternoon, and Tessa and I stood in the kitchen looking at it like a test score. A month earlier, during our home energy assessment, the same test on the same house read 2,950 CFM50. Two days of work by an insulation crew cut the measured air leakage by about 29 percent. I wrote about the assessment and the bath fan already. This is the part where we wrote a check.
Three quotes from the program list
The assessment report came with a list of contractors who were participating in Consumers Energy's rebate program at the time. I emailed four of them and three came out. For roughly the same scope, the quotes landed at $3,850, $4,400 and $5,100.
The prices weren't the only difference. The middle quote had the same R-49 target for the top attic but more vague language about air sealing. The high one added an insulated hatch box and a few items I couldn't connect to anything in our report. We went with the $3,850 company mostly because their estimator spent the longest crawling through the knee walls, and he was the only one who looked at my bath fan reroute from earlier in the month and said it could stay as it was. Their quote broke down like this:
- Air sealing: $1,350
- Top attic, cellulose blown to R-49: $1,450
- Knee walls and the knee-wall floors: $1,050
I asked up front for the final invoice to split materials from labor. That turned out to matter, which I'll get to.
Two days and one very loud hose
They came on a Tuesday and Wednesday, so I used two vacation days. Day one was air sealing. Our top attic is reached through a hatch in the ceiling of the little bonus room at the top of the stairs, and the crew spent most of the morning up there sealing wiring holes, the plumbing vent, the top plates of the walls and the gap around the chimney (metal and a fire-rated sealant there, not foam). In the afternoon they moved into the knee walls. The open joist bays under the knee walls got blocked and sealed, so attic air can't run under the bedroom floor anymore. Then the knee walls themselves got insulation and a rigid facing on the attic side, and the backs of the two little access doors got insulated and weatherstripped.
Day two was the cellulose. A truck parked in the driveway and a fat hose snaked through the side door, up the stairs and into the hatch. When the blower started, Moose took one look and left for Gary's house, where he spent the rest of the day being fed things he isn't allowed to have. It really does sound like the world's biggest shop vac. By mid-afternoon the top attic had rulers stapled to the framing showing about fourteen inches of fluffy gray, and then the blower door went back in for the retest.
The tradeoff I didn't see coming: the knee-wall spaces used to be our storage. Christmas bins, the camping gear, a box of college stuff. With the floors and walls now part of the insulated envelope, the crew asked us to keep those spaces empty. Everything came out and landed in the bonus room, which has quietly become our junk room.
What we paid, and what we expect to pay
We paid the $3,850 from savings. Our house fund is for repairs, and this was an upgrade we'd planned since the assessment.
Two things should bring that number down. The first is a $750 rebate from Consumers Energy, which I'm submitting online this week with the invoice and the contractor's paperwork. The second is the federal energy-efficiency tax credit. As I understood it when we did the work, it covered 30 percent of qualifying materials but not labor, and our itemized invoice shows about $2,300 in materials. That's roughly $690 if it works the way I think it does. My understanding is also that the credit ends for work finished after 2025, which is part of why we didn't push this to spring. Please check with a tax preparer rather than taking my word for any of it. I'm an inventory planner, not an accountant, and my father-in-law the accountant has made it clear he isn't going to read the form for me.
If both come through, our net cost is $2,410. The upstairs bedroom already feels different. The knee-wall side of the room isn't cold to the touch anymore, and on windy nights you no longer hear the wind working in the walls. Whether that shows up on the gas bill is a question for January.
For now the house sheet has a new row labeled "insulation, net (expected)" with a question mark in the cell, which might be the most honest number in the whole spreadsheet.
