AHome Office

That WorksA pioneering green builder takes on his own home office remodel—

and shares what he learned in the process.

D A V I D J O H N S T O N W I T H K I M M A S T E R P H O T O G R A P H Y B Y P O V Y K E N D A L A T C H I S O N

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This Trex deck—a composite of recycled plastic and woodfiber—offers stunning views fromjust outside David Johnston’shome office. The trellis shades the south-facing windows duringthe summer.

hen my wife and I first consideredbuying our Boulder, Colorado,house ten years ago, we climbedup on the garage roof and fanta-

sized about putting an office there. This wasgoing to be the “world headquarters” ofWhat’s Working, my environmental construc-tion consulting company, so it had to be thebest example of what is working. I wantedunique architecture that would blend intomy mountain neighborhood, a playful spacefor working and entertaining, and a roombig enough for presentations and meetings.Additionally, it had to be nontoxic and energyand resource efficient.

My architect, George Watt, helped meflesh out a final design that accomplished allof our objectives. My motivations for usingenvironmentally sensitive materials weretwofold. First, I train builders, architects,and remodelers to build green. This was mychance to gain practical experience with moreproducts. Second, I developed the BoulderGreen Points program and counsel manybuilders on complying with the program’senergy-efficient, resourceful, and healthymaterial requirements. I often hear buildercomplaints: “The products are too expen-sive,” “I can’t get my subs to use them,” or“I can’t find the products.” Using greenmaterials for my own office addition helpedme address these issues firsthand.

I was shocked, however, when I got thecontractors’ bids,—$200 per square foot,twice my budget! My remodel specificationsfreaked out even those I’d trained throughthe Boulder Green Remodeling program be-cause they’d never used materials such asstructural insulated panels. I bit the bulletand chose to be my own general contractor.

D A V I D J O H N S T O N ’ S G R E E N R E M O D E L I N G T I P S

n Consider multipurpose spaces. Rooms with multiple functions are more adaptable.

n Consider “green” financing. Contact a local professional who’s familiar withfinancing green, energy-efficient renovations. For information, go to DreamSourceFinancial.com.

n Establish good relationships with contractors. In the remodeling industry, rela-tionships can determine the quality of your project.

n Reuse onsite resources. Reusing local stone saves the cost and energy of buyingnew patio materials.

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

n Work out details in advance. When serving as your own general contractor, it’svital to develop the working ground rules with trade contractors before startingwork. When will they start? How long will it take to finish? What happens whenthey uncover unforeseeable impediments? How much is their time and materialworth? The more detailed the contractual understanding, the less opportunity forunpleasant negotiations at the end of the job.

C U S T O M I Z E F O R Y O U R C L I M A T E

Energy in your home has to be designed as a system. Whether or not you think about it, yourhome is always interacting with the environment. Hot, sunny days create one response from yourhome’s cooling system; cold, snowy days create a totally different response. By consciously ques-tioning 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 aremore efficient than automated systems because they’re in tune with your specific environment.

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From structural insulated panels to engi-neered wood beams and flooring, DavidJohnston’s home office showcases thebest of what’s working in nontoxic andresource-efficient building products.

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Recycling the Roof Thegarage’s thirty-year-old sidingwas cedar plywood, and theroof was cedar shakes—tinderwaiting for a match, especially inour mountain setting. So, as thegarage roof was taken apartpiece by piece to make way fora second floor, we saved theshingles as tinder for the woodstove. We deconstructed the ply-wood roof sheathing and sold itat a recycled building materialsoutlet, and we saved some of theplywood to sheath the newgarage walls.

Flagstones Each time theearth-moving equipmentunearthed flat stones, I asked thelaborers to pick them out of thepile and stack them for laterreuse. Reclaimed stone from allover the property became theflagstone patios around thehouse and the new office.

Structural InsulatedPanels (SIPs) SIPs—framingmaterials made by sandwichingexpanded polystyrene (Styrofoam)insulation between two pieces ofengineered wood (OSB)—are abuilding product of the future. Ofall the foams, expanded poly-styrene is the least toxic to theenvironment because it uses steamor pentane to expand the foampellets rather than ozone-depletinggases such as chlorofluorocarbons(CFCs) or hydrochlorofluorocar-bons (HCFCs).

SIPs are energy efficientbecause very little wood spansfrom the inside of the structure tothe outside, a feature known asthermal bridging. SIPs create astructure that’s better insulated andtherefore cheaper to heat andcool than conventional framing.

I chose a SIP manufacturer inBritish Columbia because it “drybuilds” the entire structure insideits warehouse to make sure all thepanels fit perfectly. One of thedownsides of working with SIPs isthat it’s a real pain when theydon’t fit together; you end up cut-ting the panels with a chain saw,resulting in a less-than-perfect fit.(Structural Insulated PanelAssociation: SIPS.org)

Roofing Oriented strandboard (OSB) isn’t the most water-resistant material; therefore, I hadto make sure the roof sheathingwas totally protected. Typically, anelastomeric membrane such as Iceand Water Shield is used only on“valleys” (where two roof planescome together) or on overhangswhere ice dams may build upand allow water to get under theshingles. Because SIPs can bedamaged by water, however, Icovered the entire roof with the

membrane. (Grace Ice and WaterShield: Na.GraceConstruction.com)

We covered the membranewith fifty-year-rated compositionasphalt/fiberglass shingles,which proved to have the bestdurability for the best price.These shingles resist hail andstrong winds; moreover, they’reeasily removed if I decide toreplace them with solar panels.(CertainTeed CompositionShingles: CertainTeed.com)

Exterior Siding The orient-ed strand board (OSB) on theSIPs’ exterior doesn’t leak air,and the panels were caulkedmeticulously when they cametogether, so I didn’t need ahouse wrap such as Tyvek butconcentrated instead on how tokeep moisture away from the not-so-waterproof OSB. The roofoverhangs protect the OSB sid-ing to some extent, but I alsowrapped the walls in thirty-poundfelt paper. We tacked the felt tothe bottom of the exterior walland worked up, mimicking theway a fish’s scales are layeredso water runs off them. We tookextra precaution at the cornersand penetrations that are morevulnerable to water. (OrientedStrand Board: OSBguide.com/osb.html; American SaturatedFelt: ASfelt.com)

Hardie Panel I hired a sid-ing company to install JamesHardie Panel, a fire-resistant sid-ing made from fiber cement thatcomes in four-by-eight-foot sheetswith a stucco pattern. We puttwo-by-fours over each of theseams in the James Hardie Panelsiding, creating a wood trim pat-tern that echoes the overall build-ing architecture. The top surfaceof each two-by-four is beveledlike a windowsill so water willrun off and away from the build-ing. (James Hardie:JamesHardie.com)

Decking Our office’s architec-tural crowning glory is the deckand trellis on the south side. Ithas the best view, and it shadesthe south-facing glass in the sum-mer, keeping the building cool.

My decking material ofchoice was a composite ofwood fiber and recycled plas-tic—my solution to the existentialangst in the grocery line whenI’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)

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Photo by Kim Master

Engineered WoodBeams The addition’s large,open architecture required seven-by-fourteen-inch beams for bothsupport and decorative purposes.To avoid cutting old-growthtrees—generally required forbeams that size—we used anengineered wood calledParallam, or parallel laminatedlumber, made from cellulosestripped from aspen trees.Stronger than pine or fir beams,the Parallam beams add a boldarchitectural accent. (ParallamBeams: USglu-lam.com)

Windows I wanted the addi-tion to be as bright and energyefficient as possible, so I choselow emissivity (low-E) windowswith specific solar heat gaincoefficients (SHGC). I used low-SHGC windows for the east andwest walls (where it tends to behottest) and high-SHGC on thesouth-facing glass to maximizesolar heat gain in winter. Theroof overhangs that blockunwanted sun in summer don’tobstruct winter light because thesun is lower on the horizon dur-ing the cold months.

I installed Heat Mirror insulat-ing glass for all the windows thatdon’t move or open. The down-side of Heat Mirror is it requiresa metal spacer between thepanes of glass because of thetension of the plastic film; thespacer tends to lose heat throughconduction. To counter the trans-fer of heat through the metal, Iburied the spacer in the woodtrim. (Heat Mirror: AlpenInc.com)

Interior Trim For highlighttrim, I installed Forest Steward-ship Council (FSC)-certified ipê,a tropical hardwood from South

America. When oiled, ipê lookslike a cross between teak andwalnut—it’s beautiful for base-boards, accents around windowand door casing, and as edgingaround the old reclaimed doors I used as desks and cabinets.(Forest Stewardship Council:FSC.org)

Flooring My wife and Iinstalled InterfaceFlor carpet tilesourselves; it took just a few hoursbecause they incorporate a peel-and-stick process for attaching to the subfloor. Not only is thecarpet 100 percent recycledcontent, but the nineteen-inchsquare tiles also come in manycolors and patterns. The carpettiles allow for flexibility; if I everneed to run electrical lines andplumbing through the floor, I canpick up only the ones I need toget the work done. (InterfaceFlor: InterfaceFlor.com)

Heating I used radiant hotwater heat in the floor—an easydecision but a challenge to exe-cute. Radiant floors are createdby laying tubing in serpentinecoils covered by lightweight con-crete (gypcrete) and wood, car-pet, or tile. I didn’t have enoughroom from the floor height to thebottom of the doors and win-dows to pour the gypcrete, and Ididn’t want to use baseboardradiators because filing cabinetsand desks would cover many ofthe walls and reduce the heaters’effectiveness. So I found a prod-uct called Warmboard, made of0.875-inch-thick, high-densityOSB, which is specially groovedfor the tubing to run through. Ilaid the Warmboard on top ofthe floor and filled in the rest ofthe floor with two layers of 7⁄16 -inch-thick OSB sheathing. It leftjust enough room for carpetingand allows the doors to open.(Warmboard Radiant Subfloor:Warmboard.com)

Water Heating For a heatsource, I first considered a tank-less water heater that hangs on awall and is plumbed like a typi-cal water heater but doesn’t storewater in a tank. Unfortunately,these are expensive and aren’tdesigned for space heating. Instead, I found an efficient A.O. Smith water heater withextra-thick foam insulation aroundthe tank and high-efficiency combustion—it works great!(A.O. Smith water heater:HotWater.com)

Natural Cooling Thanksto natural cooling, the officebuilding works like a charm.We’re blessed to be on an eastslope so the mountain blocks thesummer-afternoon “furnace” sun-light. Large pine trees provideplenty of shade. As wind patternsshift, I open and close theawning and casement windows(placed strategically on eachside of the building). Casementwindows open like doors,hinged on the side so they canact as wind scoops. Awning win-dows are hinged on the top andprovide ventilation even when it’sraining. When the wind isn’tblowing, I use a centrally locatedceiling fan for air movement.Even when it’s been more than105 degrees Fahrenheit outside,the highest temperature in theoffice addition was 84 degrees.There’s no need for air condition-ing with the building doing itsjob so well. G

NH

Natural Home & Garden JULY/AUG 2005 57

Adapted with permission fromGreen Remodeling: Changing the World OneRoom at a Time by DavidJohnston and Kim Master (NewSociety, 2004).