Special Reports
A Home Office That Works: Green Remodeling Tips

By David Johnston with Kim Master
Natural Home
July/August 2005

A pioneering green builder takes on his own home office remodel and shares what
he learned in the process.

• Consider “green” financing. Contact a local professional who’s familiar with
financing green, energy-efficient renovations. For information, go to
DreamSource Financial.com.

• Establish good relationships with contractors. In the remodeling industry,
relationships can determine the quality of your project.

• Reuse onsite resources. Reusing local stone saves the cost and energy of
buying new patio materials.

• Schedule extra time to do the job well. When working with a variety of trade
contractors, there will be times when you’re subject to other people’s
schedules. It can sometimes make the time allotted for your job unrealistic.
Scheduling too much in too small a time frame will inevitably stress you and
everyone around you.

• Work out details in advance. When serving as your own general contractor, it’s
vital to develop the working ground rules with trade contractors before starting
work. When will they start? How long will it take to finish? What happens when
they uncover unforeseeable impediments? How much is their time and material
worth? The more detailed the contractual understanding, the less opportunity for
unpleasant negotiations at the end of the job.

When my wife and I first considered buying our Boulder, Colorado, house ten
years ago, we climbed up on the garage roof and fantasized about putting an
office there. This was going to be the “world headquarters” of What’s Working,
my environmental construc­tion consulting company, so it had to be the best
example of what is working. I wanted unique architecture that would blend into
my mountain neighborhood, a playful space for working and entertaining, and a
room big enough for presentations and meetings. Additionally, it had to be
nontoxic and energy and resource efficient.

My architect, George Watt, helped me flesh out a final design that accomplished
all of our objectives. My motivations for using environmentally sensitive
materials were twofold. First, I train builders, architects, and remodelers to
build green. This was my chance to gain practical experience with more products.
Second, I developed the Boulder Green Points program and counsel many builders
on complying with the program’s energy-efficient, resourceful, and healthy
material requirements. I often hear builder complaints: “The products are too
expensive,” “I can’t get my subs to use them,” or “I can’t find the products.”
Using green materials for my own office addition helped me address these issues firsthand.

I was shocked, however, when I got the con­­tractors’ bids,—$200 per square
foot, twice my budget! My remodel specifications freaked out even those I’d
trained through the Boulder Green Remodeling program be­cause they’d never used
materials such as structural insulated panels. I bit the bullet and chose to be
my own general contractor.

Energy in your home has to be designed as a system. Whether or not you think
about it, your home is always interacting with the environment. Hot, sunny days
create one response from your home’s cooling system; cold, snowy days create a
totally different response. By consciously questioning your environment (When
does the sun rise? What rooms does the sun shine into and when? In what
direction does the wind blow in different seasons?), you create design
requirements that are more efficient than automated systems because they’re in
tune with your specific environment.

Recycling the Roof

The garage’s thirty-year-old siding was cedar plywood, and
the roof was cedar shakes—tinder waiting for a match, especially in our mountain
setting. So, as the garage roof was taken apart piece by piece to make way for a
second floor, we saved the shingles as tinder for the wood stove. We
deconstructed the plywood roof sheathing and sold it at a recycled building
materials outlet, and we saved some of the plywood to sheath the new garage walls.

Flagstones Each time the earth-moving equipment unearthed flat stones, I asked
the laborers to pick them out of the pile and stack them for later reuse.
Reclaimed stone from all over the property became the flagstone patios around
the house and the new office.

Structural Insulated Panels

(SIPs) SIPs—framing materials made by sandwiching
expanded polystyrene (Styrofoam) insulation between two pieces of engineered
wood (OSB)—are a building product of the future. Of all the foams, expanded
polystyrene is the least toxic to the environment because it uses steam or
pentane to expand the foam pellets rather than ozone-depleting gases such as
chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs).
SIPs are energy efficient because very little wood spans from the inside of the
structure to the outside, a feature known as thermal bridging. SIPs create a
structure that’s better insulated and therefore cheaper to heat and cool than
conventional framing.

I chose a SIP manufacturer in British Columbia because it “dry builds” the
entire structure inside its warehouse to make sure all the panels fit perfectly.
One of the downsides of working with SIPs is that it’s a real pain when they
don’t fit together; you end up cutting the panels with a chain saw, resulting in
a less-than-perfect fit. (Structural Insulated Panel Association: SIPS.org)


Oriented strand board (OSB) isn’t the most water-resistant material;
therefore, I had to make sure the roof sheathing was totally protected.
Typically, an elastomeric membrane such as Ice and Water Shield is used only on
“valleys” (where two roof planes come together) or on overhangs where ice dams
may build up and allow water to get under the shingles. Because SIPs can be
damaged by water, however, I covered the entire roof with the membrane. (Grace
Ice and Water Shield: Na.GraceConstruction.com)

We covered the membrane with fifty-year-rated composition
asphalt/fiberglass shingles, which proved to have the best durability for the
best price. These shingles resist hail and strong winds; moreover, they’re
easily removed if I decide to replace them with solar panels. (CertainTeed
Composition Shingles: CertainTeed.com)

Exterior Siding

The oriented strand board (OSB) on the SIPs’ exterior doesn’t
leak air, and the panels were caulked meticulously when they came together, so I
didn’t need a house wrap such as Tyvek but concentrated instead on how to keep
moisture away from the ­ not-so-waterproof OSB. The roof overhangs protect the
OSB siding to some extent, but I also wrapped the walls in thirty-pound felt
paper. We tacked the felt to the bottom of the exterior wall and worked up,
mimicking the way a fish’s scales are layered so water runs off them. We took
extra precaution at the corners and penetrations that are more vulnerable to
water. (Oriented Strand Board: OSBguide.com/ osb.html; American Saturated Felt:

Hardie Panel

I hired a siding company to install James Hardie Panel, a
fire-resistant siding made from fiber cement that comes in four-by-eight-foot
sheets with a stucco pattern. We put two-by-fours over each of the seams in the
James Hardie Panel siding, creating a wood trim pattern that echoes the overall
building architecture. The top surface of each two-by-four is beveled like a
windowsill so water will run off and away from the building. (James Hardie:

Decking Our office’s architectural crowning glory is the deck and trellis on the
south side. It has the best view, and it shades the south-facing glass in the
summer, keeping the building cool.

My decking material of choice was a composite of wood fiber and recycled
plastic—my solution to the existential angst in the grocery line when I’m asked,
“Paper or plastic?” I still can’t answer that question, but I used the recycled
bags for my decking. (Trex composite decking: Trex.com)

Engineered Wood Beams

The addition’s large, open architecture required
seven-by-fourteen-inch beams for both support and decorative purposes. To avoid
cutting old-growth trees—generally required for beams that size—we used an
engineered wood called Parallam, or parallel laminated lumber, made from
cellulose stripped from aspen trees. Stronger than pine or fir beams, the
Parallam beams add a bold architectural accent. (Parallam Beams: USglu-lam.com)

Windows I wanted the addition to be as bright and energy
efficient as possible, so I chose low emissivity (low-E) windows with specific
solar heat gain coefficients (SHGC). I used low-SHGC windows for the east and
west walls (where it tends to be hottest) and high-SHGC on the south-facing
glass to maximize solar heat gain in winter. The roof overhangs that block
unwanted sun in summer don’t obstruct winter light because the sun is lower on
the horizon during the cold months.

I installed Heat Mirror insulating glass for all the windows that don’t move or
open. The downside of Heat Mirror is it requires a metal spacer between the
panes of glass because of the tension of the plastic film; the spacer tends to
lose heat through conduction. To counter the transfer of heat through the metal,
I buried the spacer in the wood trim. (Heat Mirror: AlpenInc.com)
Interior Trim For highlight trim, I installed Forest Steward­ship Council
(FSC)-certified ipê, a tropical hardwood from South America. When oiled, ipê
looks like a cross between teak and walnut—it’s beautiful for baseboards,
accents around window and door casing, and as edging around the old reclaimed
doors I used as desks and cabinets. (Forest Stewardship Council: FSC.org)
Flooring My wife and I installed InterfaceFlor carpet tiles ourselves; it took
just a few hours because they incorporate a peel-and-stick process for attaching
to the subfloor. Not only is the carpet 100 percent recycled content, but the
nineteen-inch square tiles also come in many colors and patterns. The carpet
tiles allow for flexibility; if I ever need to run electrical lines and plumbing
through the floor, I can pick up only the ones I need to get the work done.
(InterfaceFlor: InterfaceFlor.com)

Heating I used radiant hot water heat in the floor—an easy decision but a
challenge to execute. Radiant floors are created by laying tubing in serpentine
coils covered by lightweight concrete (gypcrete) and wood, carpet, or tile. I
didn’t have enough room from the floor height to the bottom of the doors and
windows to pour the gypcrete, and I didn’t want to use baseboard radiators
because filing cabinets and desks would cover many of the walls and reduce the
heaters’ effectiveness. So I found a product called Warmboard, made of
0.875-inch-thick, high-density OSB, which is specially grooved for the tubing to
run through. I laid the Warmboard on top of the floor and filled in the rest of
the floor with two layers of 7/16-inch-thick OSB sheathing. It left just enough
room for carpeting and allows the doors to open. (Warmboard Radiant Subfloor:

Water Heating

For a heat source, I first considered a tankless water heater
that hangs on a wall and is plumbed like a typical water heater but doesn’t
store water in a tank. Unfortunately, these are expensive and aren’t designed
for space heating. ­Instead, I found an efficient A.O. Smith water heater with
extra-thick foam insulation around the tank and high-efficiency combustion—it
works great! (A.O. Smith water heater: HotWater.com)

Natural Cooling

Thanks to natural cooling, the office
building works like a charm. We’re blessed to be on an east slope so the
mountain blocks the summer-afternoon “furnace” sunlight. Large pine trees
provide plenty of shade. As wind patterns shift, I open and close the awning and
casement windows (placed strategically on each side of the building). Casement
windows open like doors, hinged on the side so they can act as wind scoops.
Awning windows are hinged on the top and provide ventilation even when it’s
raining. When the wind isn’t blowing, I use a centrally located ceiling fan for
air movement. Even when it’s been more than 105 degrees Fahrenheit outside, the
highest temperature in the office addition was 84 degrees. There’s no need for
air conditioning with the building doing its job so well.


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