Contractors who build development or “tract” homes are concerned about the productivity that results from installing the same design and repeating the same procedures over and over again. Selling at the right price is central to this building method as well. In contrast, the emphasis for custom homes is the structure's uniqueness. As a contractor, you aren't trying to achieve maximum efficiency or the least cost; the trade-off is between architectural elements and cost. These homes usually are built for owners, who often become involved in the design process and the construction details. But some homes are built on speculation too.
Building concrete homes requires a level of commitment on the part of the builder because there is a learning curve. When trades work on their first concrete home project, they tend to be nervous about how their profits will turn out. Contract proposals tend to overprotect them in terms of price. But strong loyalties for concrete home construction develop as well. Builders often specialize in concrete construction and preach the values over all other building systems.
WHY PEOPLE BUY CONCRETE HOMES
Jason Fritz, an insulating concrete forms (ICF) specialist for Cemstone, Mendota Heights, Minn., says that word of mouth is the primary way that people learn about concrete houses in his area, either through someone else or knowing someone who lives in one. He says energy efficiency is the number one reason for interest, followed by quietness and comfort.
In some parts of the country, safety from weather events is the primary reason for building concrete homes. Building codes in Florida, for instance, now require that homes withstand sustained winds of 146 miles per hour. You can build a wood house to manage these wind shears but with concrete it's much easier. For that reason, plus mold, rot, and termite protection, approximately 80% of home construction in Florida uses concrete.
Building along coastlines in known hurricane areas requires extraordinary means, but for people with financial resources who want ocean views, concrete custom home construction is the primary choice.
Mold resistance is an important issue for builders. Higher energy prices require that homes have a tighter seal, which results in trapping moisture inside walls and living spaces. With higher humidity, mold and fungus feed on cellulose—the primary ingredient of wood and paper. But there is no food source in concrete. Builders are sensitive especially to mold issues because they often get stuck with the complaints and the remediation.
A HOME IN THE BAYOU
Dave Pfanmiller, managing partner of the Security Building Group, Gulfport, Miss., specializes in building concrete homes in coastal regions. Their current home under construction is in Gulfport, Miss. The owners, whose previous home was destroyed in Hurricane Katrina, wanted to rebuild at the same location because of the beauty of the Bayou Bernard area—a short distance from the “back bay of Biloxi” and the Gulf of Mexico. The owners' children have grown up so they weren't interested in a large home. “This one will only be 3400 square feet but cost over $1 million. Not large by custom home standards, but the owners were more interested in architectural detail than gross footage and the home we are building is fascinating,” Pfanmiller says. They chose concrete because they wanted maximum storm resistance and strength, with energy efficiency as a second criterion. The first floor is twice the area of the second floor.
To avoid the destruction by another hurricane, the house is being built on a platform 13 feet off the ground. Treated timber pilings were driven to a 45-foot depth, through 25 feet of organic materials and sand after that. Pfanmiller says that the pilings depend on skin friction to support the loads along with heavy-concrete grade beams connecting them at ground level. Concrete columns measuring 12x24 inches and 12 feet long rest on the grade beams with an 8-inch-thick concrete deck attached to the top of the columns to provide the rigid elevated platform for the home.
Pfanmiller's company builds walls with a removable form building system. A high-precision aluminum forming system provides very flat wall surfaces that can become the finished surface—no drywall needed. Expanded foam insulation can be placed on the outside, inside, or in the middle. The system allows for the construction of exterior or interior walls and decks (ceilings) with unsupported spans as long as 20 feet on a 6-inch slab; longer spans can be incorporated with a thicker slab or a concrete ribbed floor system. For this home, the exterior walls, primary interior walls, and decks are concrete. The roof of the structure is wood-frame construction with strong connections to the walls creating a load path to the pilings. A standing seam steel roof completes the structure.
Pfanmiller says his company is willing to create any architectural detail that an owner wants. There are no real restrictions for using concrete. But for removable form systems, it's best for floor plans to be designed in 4-inch, 8-inch, or 1-foot increments.
CUSTOM ICF HOUSES IN MINNESOTA
Paul Vogstrom, owner of Paul Thomas Homes in Excelsior, Minn., started his company three years ago. He designs and serves as the general contractor for high-end custom homes in the Twin Cities area—a subcontractor does all the concrete work. His company only builds concrete exterior walls using ICFs. He adds that his homes are as big as 15,000 square feet but he currently is trying to figure out how to efficiently design and build concrete homes that range from 2500 to 3000 square feet that will sell for approximately $425,000.
Vogstrom says that his sales depend on word of mouth, plus biannual participation in their local Parade of Homes. His customers want energy efficiency and the comforts offered by concrete homes, but as a builder his primary concern is mold resistance. “I've had problems in the past with mold using wood construction and wish to avoid the issue,” he says.
Paul Thomas Homes builds with ICF exterior walls, wood truss floors, precast pre-stressed floor panels for garages with bonus basement rooms below, 2x6-foot interior wood-framed walls, and wood truss roofs. Vogstrom says that clients favor such amenities as wine cellars, safe rooms, secret rooms, indoor swimming pools, and special architectural appearances such as deeper window sill spaces. The 10,000-square-foot home he is building now features a swimming pool and squash court under the garage, an elevator, radiant floor heating also in the garage, and living quarters above the garage.
Vogstrom only designs and builds five or six homes per year, which is typical for custom-home builders. He says his owners can expect 65% savings on energy bills per year compared to wood structures and depending on the home insurance company they select, as much as 15% savings on their home insurance. The only real problem owners report to him is that cell phones have difficulty receiving a signal inside the structure. “But installing a $250 cell impeder resolves the issue.”
USING MORE THAN ONE BUILDING SYSTEM
Ed Sauter, an architect by training, is the executive director of the Concrete Foundation Association (which includes the Concrete Homes Council) and the Tilt-Up Concrete Association, both located in Mount Vernon, Iowa. He currently is designing a new 3600-square-foot house for himself with space for parents and returning family members. Being very knowledgeable about the industry, he has several goals. He wants to incorporate the benefits of thermal mass as an additional way to save energy, so he will specify expanded foam insulation to be placed either in the middle of wall panels or on the outside surface. He wants a prairie design with a strong horizontal look so window locations and wall heights must work out right. There also will be both low and high ceilings to add architectural interest. In the interest of economy, he will cast concrete ceilings for the first floor (all the walls and decks typically are cast at one time) but not for the second floor. And the 3 over 12-inch pitch roof covering will be standing seam steel. The hard part will be to sequence economically both removable form and tilt-up walls involved in the construction. Tilt-up construction involves casting slabs to build wall panels. This work happens on floor slabs or casting beds. Tilt-up walls also must be braced and anchored in the floor during construction. He plans to use radiant floor heating so this will mean installing anchors before floors are cast to avoid damage to heating tubes.
Sauter says that a typical problem for both removable form and tilt-up involves electrical work. Conduit typically is cast into walls and electrical contractors in many parts of the country aren't comfortable working with conduit. Builders are left with the option of hiring commercial electrical contractors, or if local codes permit, to have the concrete contractor place conduit in their forms with electricians installing the wiring afterward.
Sauter is designing an open first floor plan with minimal division of space between kitchen, living room, and dining areas (no formal dining room). In the bathrooms showers will be “walk-in” without doors, and there will be a wine cellar.
CUSTOM CONCRETE HOMES
Eventually homes with concrete walls will replace wood-framed walls because of their many advantages. Owners want safe homes that protect them from weather events and fires. Also important is energy efficiency, low maintenance, and protection from mold, termites, rot, and rodents. Comfort and quietness rank high for homeowners, but that is something you have to experience to fully appreciate.