Dense-pack cellulose + sheetrock

In late October a crew from Expert Insulation filled and packed the outside six-inch cavity of our house walls with cellulose insulation. In January they came back to fill the attic with 30 inches of loose-fill cellulose. Just 10 days ago they were back again to pack the interior cavity of our exterior walls with 10 more inches of dense-pack cellulose.

As each layer went in, the house was perceptibly warmer. Six inches was better than the outdoors, but the construction furnace ran consistently. The attic layer turned a tide; coats and fleece shirts came off and the furnace ran little—it was even turned off for days at a time. As the last 10 inches of insulation went in (and outdoor temperatures stayed in the the -10ºF to +10ºF range), we felt wrapped in a blanket of warmth.

Already we’re feeling the benefits of tightly sealed doors, windows and walls/floors/ceiling combined with the insulation: on sunny days, the house is warming into the upper 50s, falling off about 10 degrees at night, then warming back up the next day; as we need more warmth for construction, the temporary furnace has been used, but runs only a few minutes each hour. This is clearly heading in the direction we’ve imagined and are increasingly confident in the house “holding its own” once things are completed (there are still several penetrations waiting to be sealed, siding to be installed, appliances and other heat-generating sources to be added, and so on).

The insulation we’re using is called Polar Barrier, made by a company called Insolution, based in Loretto, Minnesota.

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The Expert Insulation truck arrived full of bales of Polar Barrier insulation, which were put into a hopper inside the truck, then blown through a tube to the house—like a shop vacuum in reverse.

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Matt, Jason and Brad began this last round of work by cutting and stapling a cloth called InsulWeb to the stud walls. The webbing turned the 10-inch cavities in the Larsen truss walls into channels to hold the insulation. Below, the crew cuts, drapes and staples InsulWeb to the walls.

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Once the webbing was in place, Jason began methodically filling each cavity with insulation (below). The cavities were full, but not packed the first time around.

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Insulation shooting out of of the big tube made the room dusty, and Jason wore a mask.

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In the photo below, taken after that first day, John stands next to the filled, but not-yet-dense-packed north wall. Notice air pockets in the insulation under the window. InsulWeb makes it possible to see and eliminate them in the next round.

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In a second round, Brad uses a smaller hose to add more insulation and pack it tight.

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It’s slow, tedious work but he pays attention, testing the density of the fill with his hand and watching for air pockets. It’s easy to leave gaps that will later settle, or overfill and create a wall that’s not flat, so he is careful.

We found Expert Insulation because they’re trained in proper dense-packing of cellulose and certified through a program called Minnesota Energy Resources Quality Insulation Program, administered by Center for Energy & Environment in Minneapolis.

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We were set to finish insulating 10 days ago, but a blinding snowstorm chased the crew out early that Thursday and made roads impassible the day after. They were back the following Monday and Tuesday to finish the job.

At 7:30 a.m. that same Monday, the sheetrock was delivered—a little earlier than we’d first thought, but earlier-than-later is a good thing at this point. So we made room for it, while the last of the insulation was being added.

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Then on Tuesday, as the crew from Expert Insulation was wrapping things up, the sheetrock hangers—brothers Randy and Larry—arrived and wasted no time getting started.

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Jeff was also back on site that morning to finish mounting a blocking in the mechanical room walls, and to add the last few studs to the wall under the stairway. Finally, everything was ready to be ‘buried’ in the sheetrock!

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In two short days our tangle of pipes, wires and tubes—and builders’ notes—disappeared behind a white facade.

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I was impressed by Randy and Larry’s simple tools, their speed, and their focused attitude. I hadn’t watched sheetrock installed before, so it was fun to see them quickly measure and put the pieces together.  And I couldn’t help but grin at Randy’s “tape measure” suspenders — a perfect match for what he was doing!

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Construction is clearly a give-and-take process, and striking a balance from one part of the job to the next can be a challenge. Later that day I checked in to find Larry frustrated with the volume of insulation in some of the upstairs walls, despite Brad’s persistent effort to fill evenly. Slight bulges in some channels made it difficult to firmly attach the sheetrock.

The fix, as it turns out, was fairly simple:

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Slit the InsulWeb and remove a hand-full or two of insulation to relieve the pressure. That’s really all it took!

Following completion of the sheetrock hanging, we spent time this past weekend on clean-up duty. Below, I’m sweeping up some of the excess insulation in John’s future office.

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Throughout the house we dug in to get ready for the next round of sheetrock work—taping, plastering and sanding the seams in preparation for painting in a week or two.

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Overall, it looks fantastic…an expert job on all fronts!

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Comments

Location

Lanesboro, Minnesota
Climate Zone 6 (cold/moist)
Latitude: 43° 44' 18'' N
Longitude: 91° 54' 48'' W

House Size

Net Treated Floor Area: 1,514 SF
Gross Square Footage (House only): 2,210 SF

Building Envelope

Roof: R-99
Wall: R-61
Ground: R-53

Windows & Doors

Glazing: U-0.10 BTU / hour / sq. ft.
Solar Heat Gain Coefficient (SHGC): 0.48”
Frame: U-0.19 BTU / hour / sq. ft.

Modeled Performance

Specific Primary Energy Demand (Source Energy Demand): 12.1 kBTU / sq. ft. / year

Specific Space Heat Demand: 7.0 kBTU/sq. ft. / year

Peak Heating Load: 7,047 BTU / hour

Space Cooling Demand: 0.44 kBTU / sq. ft. / year

Peak Cooling Load: 3,625 BTU / hour

Pressure Test Goal: Whole House Air Changes Per Hour (ACH) = 0.4 ACH 50

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