Mother Earth Living

Can This Home Be Greened? Mountain Metamorphosis: Saving a Colorado A-Frame Home

Can this home be saved? A Colorado A-frame needs a major structural overhaul.
By David Johnston
May/June 2010
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The new addition will provide a foundation.
Photo Illustration By Andy Johnson
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"Can we increase our space and efficiency while also enhancing the connection to our scenic backyard and friendly neighborhood?" 
—Kathy Ellis

Finding an affordable house in Boulder, Colorado, where a small 1940s bungalow can sell for more than $500,000, requires a lot of legwork and even more imagination. The Ellis family felt fortunate to find a house on a half-acre of land in a great part of town with beautiful views. The down side? The 1967 modified A-frame needed an upgrade on every level—starting with the foundation. “We knew we were buying a dream, not a dream home!” Kathy Ellis says. “We had toyed with the idea of doing a tear-down, but that’s just not green.” The question became not so much if this home could be greened, but if it could be saved.

1. The house is barely standing.

Problem: Two of the structure’s load-bearing walls do not connect to the ground. (As strange as that seems, it shows how long a building can last without a solid foundation.) A grade beam is under the house, but one wall cantilevers over the foundation by at least 6 inches, and the opposite “wall” is really the A-frame’s steep roof. The bolts that attach the roof to the floor are actually holding it up.

Solution: The solution to this major problem will become the basis for a redesign. Architect Andy Johnson designed an addition that runs perpendicular to the home’s current east-west axis. The new addition’s foundation can pick up the existing building’s load. The remodel will reverse the existing layout: The current living room will become the garage; the future living area will be part of the new addition. A new foundation under the garage will provide structure for that end of the house.

Cost: Approximately $200,000

2. The old windows are leaky.

Problem: The home’s aluminum-frame and site-built windows conduct so much heat to the outside that they literally freeze the condensation inside, and the windows don’t close properly. The house has so much single-pane glass, primarily facing west, that the wall assembly’s average R-value is probably around R-4.
 
Solution: Fortunately, Boulder is home to one of the country’s best window manufacturers, Serious Materials, which offers foam-filled fiberglass windows with glazing as high as R-14. The company’s operable windows range from R-7 to R-11; a typical low-E window is roughly R-3. Redistributing these windows around the house would allow passive solar gain on the south side and reduce the extensive west glazing, which causes severe overheating. Serious Materials can “tune” windows according to the wall’s orientation. South windows should have a high solar heat gain coefficient to gain passive winter heat. East and west windows should have a low solar heat gain coefficient to keep out summer heat.

Cost: Approximately $35,000

3. Insulation is minimal.

Problem: In this A-frame, the entire north wall is the roof. It was built as a post-and-beam structure with large 4-by-12 supports spaced roughly 4 feet apart (although the spacing is inconsistent). On top of the beams is 1½ inches of tongue-and-groove roof decking, 1⁄2-inch of asphalt-impregnated fiber insulation board (Celotex) and wood shakes. The only insulation comes from the wood (R-1 per inch) and the fiber insulation board (R-1.23). As a result, the house is always cold in winter and hot in summer. On cold evenings, the Ellises are only comfortable in front of the wood stove.

Solution: Gut the walls and re-insulate using wet blown-in cellulose insulation, then wrap with 2 inches of rigid, closed-cell polyisocyanurate foam. Insulating over the studs eliminates the problem of thermal bridging—when wood studs conduct heat out of the house. Build the new addition’s roof structure using Structural Insulated Panels (SIPs) with an R-value of 54. Cover the existing roof
structure in SIPs with an R-value of 42. SIPs are one of the easiest ways to get high R-values, because they can be made in any thickness to suit any need. SIPs consist of three parts: an exterior skin (typically oriented strand board, or OSB); an insulation layer (in this case, high-density polyurethane foam); and an inside skin (typically OSB or drywall). They provide a very energy-efficient and well-sealed envelope that prevents mold growth and air-infiltration problems.

Cost: Approximately $15,000

Renovation tips

1. Prioritize. Addressing structural and energy-efficiency concerns first will ensure your home is healthy and durable. Tackling your home’s basic structure should be the first step in any renovation.

2. Focus on windows. The U.S. Department of Energy estimates Americans lose 5 percent of energy through leaky windows. Replacing old windows is an extremely efficient use of remodeling dollars.

3. Design for passive solar. Consider your windows’ layout when renovating a home. Well-placed, south-facing windows can help gain winter heat and keep out unwanted summer heat, reducing energy bills.

Remodel for health

I was consulted on a Colorado home that exemplifies the importance of addressing structural issues before aesthetics. The homeowner had remodeled a 1972 house to improve the kitchen and master suite and installed a photovoltaic system. Her home was beautiful, but her kids were sick all the time, and  she had constant migraines.

Her home’s roof had been leaking for years, and water was inside the walls and ceilings. The house was built into a mountainside with no drainage. Mold was growing in the walls, ceilings and floors. In addition, the drywall was cracking around the exterior because the footings were too shallow and the house was shifting.

The moral of the story: Always remedy structural and health-related problems before renovating for aesthetics and alternative energy. This homeowner loved her new kitchen and bedroom, but she couldn’t live in her house.

Resources

Applegate Insulation
cellulose spray-foam insulation

Earthcore SIPs
structural insulated panels (SIPs)

Serious Materials
efficient windows

David Johnston is the president of What’s Working, a Colorado sustainable building consultancy. A Natural Home editorial advisory board member, he received the 2007 International Sustainability Pioneer Award.


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