cellulose insulation

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Building an Airtight Envelope

In Connecticut, Michael Trolle continues construction of his Passivhaus home with a roof, insulation, and high-performance windows from Europe

Posted on Nov 3 2015 by Michael Trolle

Editor's note: This is the third installment in a series of blogs by Michael Trolle about the construction of his Passivhaus home in Danbury, Connecticut. The first part was published as “Building My Own Passive House.”

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Insulating With Damp-Spray Cellulose

It’s cheaper than spray foam, air-seals better than fiberglass, and has more recycled content than both of them

Posted on Mar 26 2015 by Leroy Anthony

Insulating any building can be a challenge, but the nonprofit energy-efficiency and weatherization company I work for, Community Environmental Center, frequently insulates old houses being rebuilt for residential group homes and elderly housing in New York City. These skilled-care buildings, like the one shown in these photos, are crammed with pipes, ducts, and wires, so they’re tough to insulate. They’re also located in dense urban neighborhoods that can be busy and loud.

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  1. Patrick McCombe

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New Videos: Sealing Ducts and Installing Dense-Packed Cellulose

GBA presents two new videos, both recorded at NESEA's Building Energy 13 conference in Boston

Posted on Apr 17 2013 by GBA Team

GBAGreenBuildingAdvisor.com has released two new videos: one on installing dense-packed cellulose in stud cavities, and the other on sealing duct seams with mastic.

Both videos were recorded in March 2013 at NESEANorth East Sustainable Energy Association. A regional membership organization promoting sustainable energy solutions. NESEA is committed to advancing three core elements: sustainable solutions, proven results and cutting-edge development in the field. States included in this region stretch from Maine to Maryland. www.nesea.org's Building Energy 13 conference in Boston.

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  1. GBA video

A Thick Cocoon of Cellulose Protects This Superinsulated House

Warren, VT

Oct 15 2010 By | 28 comments

General Specs and Team

Location: Warren, VT
Bedrooms: 3
Bathrooms: 2
Living Space : 1922 sqf
Cost (USD/sq. ft.): $105/sqf

Builder: Riversong HouseWright
Home performance consultant: Efficiency Vermont
Insulation contractors: Riversong HouseWright, with help from Bill Hulstrunk of National Fiber


Foundation: Slab placed inside of a frost-protected shallow grade beam
Underslab insulation: Horizontal R-10 XPS under entire slab and vertical R-10 at slab edge
Foundation perimeter insulation: Vertical R-10 XPS at exterior of foundation and 12" of R-10 horizontal wing insulation
Walls: Inner load-bearing wall is rough-sawn 2x4s, 24" o.c.; platform-framed first story, balloon-framed second story with let-in wooden ledgers for ceiling joists and rafters. Outer wall: parallel-truss chords of rough-sawn 2x3 extending from sill to rafter tails, gusseted to studs with rough-sawn 1x4s.
Wall bracing: Let-in metal T-bracing (Simpson TWB)
Rough openings: ½" CDX window & door boxes; Tremco acoustical sealant or EPDM gaskets used for air sealing
Wall insulation: R-45 dense-packed cellulose
Siding: Pre-finished spruce novelty drop siding over Typar
Exterior trim: rough, band-sawn 1x boards
Ceiling insulation: R-68 cellulose
Roof framing: rough-sawn 2x10 rafters
Roof sheathing: rough 1" pine board sheathing
Roofing: Laminated asphalt shingles
Windows: Pella Proline aluminum-clad wood windows (double-hungs and casements) with double-pane low-E² glazing (U-factor: 0.32, SHGC: 0.31)


HERS rating: 46
Passive solar design features: Oriented for passive solar heat gain; solar gain satisfies an estimated 28% of the home's heat load.
Blower-door test results: 3 ACH @ 50 Pa with air inlets open; 2.13 ACH @ 50 Pa with air inlets closed.
HERS estimated energy use: 42.8 MMBtu heat, 15.6 MMBtu hot water, 19.4 MMBtu lights & appliances.
HERS estimated annual energy cost: $2,418
Actual energy use (Nov. 2009 – Mar. 2010): 1 cord firewood, 145 gallons propane, 200 kWh/month electricity. (Estimated annual energy cost, extrapolated from winter use: $1,563.)

Space heating: Triangle Tube Prestige 94% AFUE 30,000-110,000 Btu/hr modulating condensing direct-vent boiler with outside reset; wood stove with ducted outdoor combustion air, vented to a masonry chimney.
Heat distribution: in-floor hydronic (1st floor: tubing embedded in slab; 2nd floor: PEX tubing suspended 2" under subfloor with bubble-foil radiant barrier).
Domestic hot water:: Triangle Tube Smart 40 indirect tank
Appliances and lighting: Energy Star appliances and hard-wired CFLs throughout

Water Efficiency

● Efficient front-loading washing machine
● Low-flow shower heads
● 1.6 gpf toilets
● No dishwasher

Indoor Air Quality

● Low-VOC paints and finishes
● Solid pine cabinetry
● Softwood, tile, and concrete floors
● Borate-treated cellulose insulation
● Operable windows designed for effective cross-ventilation

Mechanical ventilation system: Exhaust-only ventilation with timed Panasonic bath fans and Airlet 100 make-up inlets

Green Materials and Resource Efficiency

● Minimal site disruption (excavation only 12" deep)
● Minimal use of concrete (10" x 20" grade beam and slab)
● All concrete form boards re-used in house framing
● Local, rough-sawn, green hemlock lumber
● Local, rough-sawn exterior hemlock trim
● Builder-felled pine trees milled into boards for 2nd floor and roof decks
● Exposed interior load-bearing timbers felled and milled within 5 miles
● Negligible engineered lumber (plywood window boxes)
● Fewer board feet of lumber than a standard 2x6 house, but with 12" walls
● Tinted slab as finished floor

This comfortable, practical, and ecologically responsible house was also affordable, thanks to a crew combining skilled workers and trainees, a sweat equity contribution from the owner, and “time & materials” billing by the builder

By Robert Riversong

I was hired to design and build a home for a Vermont land owner who wanted a house that would be affordable to build, affordable to live in, as green as possible, accessible as she aged, and able to generate rental income.

We collaborated on the design, planning, permitting, and site work. We created a floor plan that would place all necessary living spaces on the first floor. The second floor has a great room, two additional bedrooms, and a second full bath so that she could rent space to boarders.

Lessons Learned

Put everything in writing
I've made it a practice to draft a memorandum of understanding (MOU) at the start of any major building project, to make sure that initial agreements are not later misconstrued, and that each party understands their respective roles and responsibilities. I include a mediation clause, in the event of “irreconcilable differences.”

I had agreed to design and build this home because the client stated her intention to grow old in it and had somewhat limited resources. Because I work for a very fair hourly wage, pass on my material costs without markup, and don't charge for overhead or profit, I can build a house like this for as little as $100/sq. ft. in a market in which ordinary custom homes start at $150/sq. ft. I'm willing to put in a personal subsidy for someone with an authentic need for housing and in order to create another example of a truly “green” home.

So I was surprised and disappointed to learn that the house was put on the market less than one year after it was built. If I were to engage in such a project again, I would require an equity-sharing agreement to recover my subsidy if the house were to change ownership within ten years. The silver lining, perhaps, is that dozens of sustainable building students were able to tour the house during and after construction, it's received some attention on the Web and in the building science community, and the young couple who now own it are thrilled with its performance.

Robert Riversong

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  1. Robert Riversong

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