|A small house on a tight lot, the bungalow was a perfect candidate for a second-floor addition. The trim, roof pitch, harmonizing colors and a chimney extension made from matching bricks complement the architecture of the 1912 house.
After photos by Fotoimagery.com
Back in 2000, clients of Classic Homeworks, the Denver residential remodeling company Rick Pratt founded, were not too excited about green remodeling. Yet he had always considered himself an environmentalist and wanted to introduce energy-saving, environmentally friendly designs and products to his business.
So he did a green remodel on his own house, a 1912 bungalow in an old, in-town neighborhood. Pratt purchased the single-story home in 1991, intending to fix it up and sell it. After modernizing the 900-square-foot basement and 1,170-square-foot first floor, then adding a garage, Pratt designed a pop-top addition with a master suite, laundry room and two bedrooms for his teenage children. The 1,050-square-foot second floor would make room for a family room and spacious office on the main floor where bedrooms had been.
"We finally had a house my wife really loves," Pratt says. "She was not going anywhere."
Pratt seized the opportunity to build the addition with green products and systems he'd rarely been able to try. The end result: 90 percent more aboveground square footage (50 percent more total square footage), with no increase in electricity usage and only a 28 percent rise in the heating bill.
As he designed the pop-top, Pratt considered energy savings, environmental conservation and health. For energy efficiency, Pratt selected a 90 percent efficient sealed combustion furnace; double-pane, argon-filled low-E windows that reduce solar heat gain; and a washing machine that uses three or four times less water than conventional models — it has a high rpm spin cycle that gets so much water out that the dryer doesn't have to run long. All of the new lighting uses compact fluorescent bulbs, which provided one of the project's biggest net energy gains.
Other product picks saved water: The after-market showerheads use less water than typical fixtures and the bathroom switch activates the hot water recirculation pump when someone wants to take a shower.
He chose the fiber-cement, stucco-look siding panels for their long lifespan. They look great, he says, and hold paint and finishes "far better than natural wood products." Some products, such as the solvent-free construction glue and the low-phenol formaldehyde OSB panels used on the exterior sheathing and part of the sub-floor, are environmentally friendly because they don't off-gas as much as standard materials.
Pratt selected other products because they save resources by using recycled materials. Take the roofing made from old tires. "You can see the texture on the underside and patches from flats on some," he says. Also noteworthy: the cellulose insulation made of recycled newspaper, and the drywall, composed of gypsum created from power plant waste material. Pratt conserved resources himself by putting the home's old roof rafters to work as nonstructural ceiling framing.
He also took all lumber scraps, copper pipe cuttings and cardboard boxes from the construction site to a recycling center.
Typical of older houses in town, Pratt's bungalow had double masonry exterior walls without a speck of insulation between them, says energy retrofit specialist Dennis Brachfeld. Even some newer houses in the area aren't insulated, says Brachfeld, a certified home energy rater whose Denver company, About Saving Heat Co. (www.aboutsavingheat.com), participated as insulation contractor and consultant in this remodel. Wall insulation did not become a Colorado code requirement until 1979.
For that reason, Pratt needed a plan to segregate and control energy use in the pop-top. Rather than open the existing building, he built the second floor on top of the existing first-floor ceiling. He left the furnace in the basement to heat the existing home, then added a new energy-efficient one in the attic to use exclusively for the addition. He created a tight envelope around the pop-top to prevent air leaks, gluing the wall plates to the sub-floor and caulking and sealing all lumber connections.
An overly tight house can seal in toxins, but Pratt didn't need to worry about that. "Half of my above-grade house is old," he points out, "so there still is plenty of ventilation, and the bathroom fans still allow ventilation."
The biggest challenge of the job, says production manager Jim Wilkinson (then a lead carpenter), was the framing. "This was the first house I'd framed with TJIs for rafters," Wilkinson says. Pratt specified the I-joists because they are resource-conserving, straight and lightweight. But because each joist rafter was not a solid wood", explains Wilkinson, "We had to put plywood on each side of the ends before we could install them into the hangers."
A carpenter since 1981, Wilkinson also faced a learning curve with optimum value engineering (OVE), which calls for framing with 2×6s 24 inches on center, with open corner framing, ladder blocks for interior wall connections, and open headers. OVE uses fewer studs and more open wall connections, which seemed to go against common sense.
"The natural mindset of most carpenters is that bigger is better," Wilkinson says.
Now Wilkinson's a convert to the OVE framing system. "It saves trees and creates more insulation space," he says. "We do this on every project now."
Pratt and Brachfeld put their heads together to design an insulation plan that covered all bases. Typically pop-top plumbing is run in the 18-inch cavity between the first-floor ceiling and the second floor. In Denver's cold climate, Brachfeld says, "Poorly built pop-tops can sometimes see pipes freeze." To prevent problems in the Pratt house, he blew a 24-inch-wide ring of insulation around the perimeter of that cavity, helping to define and seal the second-floor envelope. His company also filled the addition walls and roof with densely packed cellulose insulation.
The attic has minimum R-40 insulation and good roof and soffit vents. The furnace occupies a small, fully insulated room in the attic, so no heat is wasted. All heating ducts are insulated with a minimum R-15 blanket insulation and then covered with cellulose. On Brachfeld's advice, Pratt runs the furnace fan continually.
"A furnace wastes the most heat when it is cycling on and off," Brachfeld says. "If the fan is running, you deliver more of the heat you pay for."
The house is not air-conditioned, yet remains comfortable even in the summer. "The warmest it gets inside is 78 percent of the outside temperature," Pratt says. "Most pop-tops are 90 degrees if it's 100 degrees outside." A whole-house attic fan runs all night during the summer, while open windows draw cool air into the bedrooms and expel hot attic air. Each bedroom has a ceiling fan with curved, propeller-like blades that push 50 percent more air than other ceiling fans, says Pratt.
|In the master bedroom, low-E windows with accordion blinds allow light and views but cut glare and heat gain. A glass-block wall at the head of the stairs, behind the bedroom's partial wall, draws in natural light, illuminating the stairwell.|
Weighing the results
Though the house practically doubled in size, Pratt's electrical usage did not increase at all. He attributes most of that achievement to the lighting, because the savings from the extra-efficient washer and dryer were probably offset by the installation of the whole-house fan.
Post-remodel, Pratt's heating bills rose only 28 percent on average despite the home's increased size. He was delighted.
After 6 years living in the remodeled home, Pratt wanted to test its performance. He brought Brachfeld in to conduct a blower door test to measure air leakage in early 2006.
"It was very eye-opening," says Pratt. "There were some leaks in the heating system; we should have installed fully ducted return air rather than using the framing bays as ducts."
Most air leaks, however, were occurring on the main floor, at the front door, around the fireplace, around some windows, at an old rear addition and in the exterior masonry walls where there are cracks.
In retrospect, Brachfeld and Pratt realized they should have paid more attention to the existing structure instead of focusing all their efforts on the additions.
"I have a lot of caulking to do on the exterior and interior of the [original] house," Pratt says.
In hindsight, Pratt notes a few other lessons learned. If he had to do it again, he says, he wouldn't bother salvaging the old rafters: "It took too much time and energy to prep them for use." He'd choose a different recycled rubber roofing — although the hail-proof rubber material earned Pratt a $450 annual discount on his homeowner's insurance, this particular product is fading — "failing cosmetically" — and the manufacturer is no longer in business.
He'd also test the whole house at the outset. "Everybody should test every house they work on," he says. "They will learn a lot from this process."