Adobe up north

Q: We are in the process of purchasing a Santa Fe style adobe home in British Columbia. The house is a 4,200-square-foot bungalow with a large courtyard. There is a veranda that pretty much wraps around 80 percent of the house. The roofing material that covers the veranda is of the board and batten concept and because of the winters that they get here, it is looking not so great. I would like to replace this roofing with a metal roof system. My question is what profile roofing material would be optimum and in what color?
—Robert Charbonneau, Penticton, British Columbia

A: Covered exterior spaces provide the best of both worlds—outdoor enjoyment and protection from the beating sun, whipping wind, and soaking rain. Metal roofing works particularly well for structures in the Southwest because these materials stand up against environmental factors such as the ever-present sun. Shingles are more susceptible to sun damage, especially in this area, explains Tom Cockroft of Sun Metal, a metal roofing company located in Albuquerque.

According to Cockroft, the material you select for your metal roof depends highly on your budget for the project, as prices for different roofing materials vary widely. Some of the higher-end metal roofing choices are copper, which can be treated with chemicals for a green finish, and zinc. These materials cost more but do not rust. (Expect higher-end products to last longer.)

Rusting and leaks aren’t as prevalent in the arid Southwest as in areas with consistent water exposure. Locations with steady rain and snowfall do well with painted aluminum, copper, or titanium roofing—more demanding environmental conditions almost require the use of these higher-grade materials, Cockroft says.

Corrugated galvanized steel is a frequently chosen roofing option, but understand that this material will eventually rust, according to Cockroft. A material called Galvalume is similar to galvanized steel, but rather than having a layer of zinc alone, Galvalume has a layer of zinc and aluminum, which helps prevent rust. Galvanized or Galvalume roofing is often painted, which further protects the material, Cockroft says. Those who actually prefer a rustic-looking roof can purchase metal roofing with a prerusted finish.

Popular styles for metal roofing include corrugated galvanized, corrugated rusted, and metal roofs painted in earth tones, rust red, green, or blue.

According to Cockroft, standing seam metal roofs, which are more expensive than surface-mounted panels, perform better and are less prone to leaking, which makes them a good option if you live in an area with frequent precipitation.

The ABCs of ICFs
Q:We are planning to build a new home outside of Cortez, Colorado, and are exploring ICF construction. However, we have talked to two architects and have gone to some solar workshops and have been advised against the concrete construction. They say it creates an envelope that is not a good insulator, and we are very confused, as we like the look of the thick walls and the heavy construction. Can you give us any enlightening information on the ICF construction as opposed to a frame house? We plan to use passive solar and panels for heating the in-floor heat and domestic hot water.
—Jerrie Akey, Rico, Colorado

A:Let’s begin with the basics. Insulated concrete forms (ICFs) are hollow blocks or panels made of recycled foam, which are filled with concrete and rebar. This sculptable material is strong, has mass and good sound control and R-values, producing durable homes resistant to wind and fire. The Insulating Concrete Form Association reports that building with ICFs saves energy and money because of the insulating properties of the material. ICF homes are also quiet and retain an even temperature.

As a green-building system, ICFs are a mixed bag, according to architect Beverley Spears, FAIA, owner and principal of Spears Architects in Santa Fe, referring to the high embodied energy of the concrete and steel. On the other hand, frame construction can involve logging to obtain the wood. Most would agree there is not one perfect system.
Homes built with exterior concrete walls have a number of benefits, including superior energy efficiency, according to information from the National Association of Home Builders. The association cites energy savings and a smaller insurance premium as two areas in which the monthly operating cost of living in a concrete home is less than that of a conventionally built house.

A house built with ICFs is much more solid than a frame house, Spears adds. She notes that the walls are thicker and have good acoustical properties. Regarding claims about insulation problems, Spears says she doesn’t think they are necessarily true. The wall itself is the insulation in an ICF home. She recommends comparing the R-values for the different construction materials you are considering. The R-value is a measure of the resistance to heat flow through a material. The higher the number, the better the material’s insulating properties.

As you study these comparisons, understand what you are comparing. Dan Hagan, a project engineer for the Energy Conservation and Management Division of the New Mexico Energy, Minerals and Natural Resources Department, also advises that you look at the R-values. He warns that manufacturers sometimes state R-values with a descriptor, such as “effective R-value” or “equivalent R-value.” He says the value you really want to know is the “steady state R-value.” He says this value is obtained through a laboratory test, and smaller manufacturers might not have this test done.

If you can’t find out from the manufacturer what the steady state R-value is, you can come up with an approximate R-value on your own. Look at the total thickness of the insulating material, such as foam, and determine the R-value using the known figure of R-value per inch for a particular material, Hagan says. For instance, if the ICF has two inches of foam, then concrete, then two more inches of foam, count a total of four inches of insulating material. (He notes that it’s more difficult to find out R-values per inch for aggregate materials.)

If an ICF claims to have an R-value of 35, and with its four inches of R-4 material, you estimate its value is about R-16, you might not be getting what you think, Hagan says.

A good source for the R-values of different materials is a fundamentals manual from the American Society of Heating, Refrigerating and Air-Conditioning Engineers, which can sometimes be found at libraries, Hagan notes. You can also go to a building supply store and find foam labeled with a particular R-value per square inch. R-values add going through the wall, Hagan says, so if you have two sheets of an R-5 material, the total value is R-10.

Whether you choose a frame house or an ICF house, you will want a good R-value and a house that is airtight, Hagan advises. Most concrete forms will not allow air movement, but he adds that properly insulated frame houses won’t, either. Now infiltration barriers used on frame homes help prevent air from blowing into the walls, and fiberglass insulation is effective, he adds. The key is that the insulation is installed correctly—he says to make sure all spaces are filled up. People sometimes compare properly constructed ICF homes to homes with fiberglass insulation that was not installed correctly, Hagan explains. If you choose to go with ICFs, he recommends hiring a builder who is experienced with them.

In terms of cost, Hagan says building with ICFs can be more expensive than building a frame house. However, remember that the wall system accounts for a relatively small portion of the total cost of the project (he estimates 10 to 15 percent).
According to the Insulating Concrete Form Association, building a house with concrete exterior walls adds approximately three percent to the sale price of the home, compared to a frame house. ICF advocates argue that this additional up-front cost is worth the tradeoff for the benefits the system provides, including energy savings.

Earthly abodes
Q: We live in Calgary, Alberta, Canada, and are considering building a Southwestern style home using Advanced Earthen Construction Technology—structural masonry blocks made from soil that has been compressed by a hydraulically operated machine. What do you know of this technology, and would you recommend its use in our temperate climate?
—Bonnie Couture, Calgary, Alberta

A: No matter where you live, think about what makes sense for your location and circumstances when choosing building materials for your home. Jim Rogers, AIA, of J. S. Rogers Architects, PC, says earth blocks would not be his first choice for that area. Rogers has designed many rammed earth homes and has worked with Rastra, ICF construction, and other alternative building materials. Although a high-compression product is better suited to the area than regular adobe, Rogers says considering the precipitation and temperature extremes, he would think about another building material.
If your interest lies with using a specialty masonry product, in Rogers’ opinion, insulated concrete forms would be a better choice. ICFs form solid, quiet homes with built-in insulation—homes that create the same feeling as earth construction, Rogers says.

Perhaps an ICF misses the mark for you, however. If your goal is having earth walls around you and a substitute won’t do, you can build with compressed masonry blocks and prepare for your area’s conditions. Make sure the home is well-constructed and that you maintain the home properly. Design for the winter there, Rogers advises—you will want overhangs and insulation under the home’s slab. Insulate the home’s exterior with at least four inches of foam; insulating a mass home keeps the heat in and promotes a stable temperature within.

While Rogers says he likes ICFs, he concedes that they aren’t best for all applications. Besides ICFs, you can consider additional material choices, such as structural insulated panels (SIPs), made with foam and plywood veneers. This product is a good insulator and creates a tight home, according to Rogers.

With so many choices available, start by learning what people in your area are building with, Rogers says. In this case, find out who makes compressed earth blocks in Alberta. Many factors influence the “greenness” of a building product, including whether a particular product must be trucked in from miles away. Try to find an appropriate solution for your home and situation, Rogers advises.

Across the pond
Q: In the Autumn 2006 Su Casa, there is an article by Jane Mahoney on a house that was designed by Don Dudley. It has a cooling pond that is very interesting to me. I have a cabin on the Mojave and would like to put a cooling pond in. I believe the pond is on the south side; is that correct? How could I find the distance from the house and the size the pond should be? We have a primitive solar heater for our outside shower and a funky outside kitchen that I love to slosh around in, and also good southern exposure.
—Maria Huff, Twentynine Palms, California

A: The Donnelly residence, featured in Su Casa’s Autumn 2006 Green Home department, incorporates a number of energy-conscious design elements, including the distinctive and functional cooling pond. Architect Don Dudley, AIA, designed the Donnelly home. “The cooling pond is based loosely on cooling principles the Moorish employed in the arid regions of what is now Spain,” Dudley explains.

When you place water in a vessel with a high albedo, or reflective power—and Dudley notes that the color black is high—the water begins to transpire to vapor. This vapor is carried inside the house by prevailing winds from the southwest in the summer, Dudley says, which begins to moderate the environment inside.

The cooling pond at the Donnelly residence is 10 feet by 10 feet and 24 inches deep, according to Dudley. The pool is placed about five feet from the face of the house. However, Dudley says that there is no formula to follow here, rather guiding principles of how the cooling process works. 

Expert contact info:
Adobe up north: Tom Cockroft, general manager, Sun Metal, Albuquerque, 505/247-2278, sunmetalroofs.com.
The ABCs of ICFs: Beverley Spears, FAIA, owner and principal of Spears Architects, Santa Fe, 505/983-6966, spearsarchitects.com.
Dan Hagan, project engineer, Energy Conservation and Management Division, New Mexico Energy, Minerals and Natural Resources Department, Santa Fe, 505/476-3310, cleanenergynm.org.
Earthly abodes: Jim Rogers, AIA,
president of J. S. Rogers Architects, PC,
Albuquerque, 505/247-1168.
Across the pond: Don Dudley, AIA, owner of G. Donald Dudley Architect Ltd., Albuquerque, 505/243-8100,
dondudleydesign.com.