One story houses with back doors and private laundry facilities are the most livable but least affordable homes. Eliminating private laundry facilities reduces the cost but lugging laundry to and from a public laundry is a nuisance, and the machines are not always available. Eliminating the back door saves the cost of the interior pathway to the door, but then there is no direct access to the area behind the building.
Joining houses at the side produces rowhouses. This saves the cost of the exterior walls that have been eliminated and reduces land cost per unit by eliminating the land between units. However, livability is degraded by the noise transmitted through the walls between units.
A unit in a building with a full second story is less expensive than a unit with similar rooms in a one story building because there is less area per unit for land, footings, and roof. Two story buildings can have either rowhouse units or stacked units.
The savings for a two story rowhouse unit are partially offset by the cost of the space consumed by the stairway and the requirement for a bathroom on each floor. Livability is reduced by the inconvenience of the stairway and by the impact noise generated in the second story. However, in large units the inconvenience of the stairway is offset by the reduced average distance between rooms.
The savings for stacked units are greater than the savings for rowhouse units because there are no extra bathrooms and there is only one stairway. The savings are partially offset by the requirement that first story units be wheelchair accessible, which requires oversized bathrooms and utility rooms. Furthermore, first-story occupants will suffer from impact noise generated above them.
Stacking units more than two stories high makes them even more affordable. But a tall walk-up is the least livable building because many units will suffer from impact noise, formidable stairways, or both.
Using elevators to supplement the stairways in tall buildings makes the units more livable, but then all units in stories serviced by the elevator will be required to be wheelchair accessible. If there are more than twenty units, special provisions will be required for deaf people and blind people. These costs can be justified only if the land is so expensive that a tall building is the best use of the land.
The buildings are designed to provide affordability by controlling construction, operating, and occupancy costs. Occupancy costs are those additional costs incurred by occupants because of inadequate facilities. In a free market all these costs are borne by the occupant, whether owner or renter.
The buildings are compact because they have simple shapes. This not only reduces the cost of the building, it also reduces the land cost per unit by increasing the number of units that can be placed on a site.
Exterior wall lengths are exact multiples of two feet, allowing standard lumber sizes to be used with no waste. Exterior walls use 4-inch studs, which can be provided with enough insulation to suffice in even the coldest climates. Using larger studs would cost more and would waste space.
There are no basements, except for walkout basements on buildings designed for hillside lots. The extra space provided by a basement, although relatively inexpensive, is far less useful than space above ground. In cold climates, a frost-protected shallow footing is a more practical choice than a basement.
There is no living space in attics. It is costly to provide adequate insulation and ventilation above attic living space.
A garage is treated as a room of the house, not as a separate entity. This allows the garage floor to be placed at the same time as the floors of the other rooms, reducing labor costs.
Roof slopes are steep enough to allow the use of inexpensive covering materials. However, slopes are not so steep that significantly more material is required.
Heating costs are minimized by designing for passive solar heating and by using cantilevered roof overhangs that provide more room for insulation above the exterior walls. The buildings have most windows placed on long walls on opposite sides of the building, so that one of the window walls can face south to collect solar energy.
Air conditioning costs in summer can be as high as heating costs in winter. To reduce dependency on air conditioning:
The superior attic ventilation also minimizes water damage caused by condensation under the roof.
All units have substantial kitchen facilities. If the kitchen is inadequate, food costs will be higher because occupants will buy prepared food more often.
Except for the smallest unit, all units have private laundry facilities. This eliminates the cost and nuisance of going to public laundry facilities.
Most units have a door providing direct access to a back yard or common area. Without a back yard or common, the cost of recreational and social activities will be higher because occupants will pursue these activities elsewhere.
The public area has an informal living room and an eat-in kitchen. These provide social, recreational, and dining facilities for family and guests. The dining table in the kitchen serves a second function by providing additional food preparation area.
The informal living room makes a family room unnecessary. The eat-in kitchen makes a dining room unnecessary except in the largest houses.
The main entry accesses the living room and provides a pathway along one side to other rooms. This prevents cross traffic from interfering with living room activities. Bedroom closets are in one of the walls near the bedroom door to minimize the length of the pathway to the closet. There are no great rooms because they are essentially inefficient pathways.
Rooms are large enough to accommodate the intended furniture. Even the smallest bedrooms can be furnished with a queen-size bed, a chest of drawers, and a desk.
Wall space is maximized to facilitate furniture placement. Except for kitchens, windows are just large enough to meet code. There are no fireplaces, so living rooms provide three walls for furniture. Bedroom closet doors are arranged to provide enough space to butt furniture against one end of the closet.
In most units, the kitchen is L-shaped with a door and a window facing the back. Patio doors are not used because they function poorly as either a door or a window. There are no cabinets above refrigerators, ranges, or sinks because short cabinets are not cost-effective. The corner has a sink, not cabinets, because inexpensive corner cabinets are awkward.
The buildings use slab foundations. This eliminates the noise transmission under the floor that would occur in a raised foundation. Bedrooms are separated either by closets or by sound-resistant walls. In duplexes, bedrooms are on the outside and rooms less sensitive to noise are on the inside.
It is recommended that bathroom doors be solid wood. Hollow doors would allow enough noise transmission to reduce privacy.
The slab foundations provide thermal mass to reduce temperature fluctuations. A raised foundation does not provide thermal mass.
Exterior walls are especially subject to temperature fluctuations. To minimize this problem, the cantilevered roof overhangs provide more space for insulation at exterior walls and a register in each habitable room sends conditioned air to exterior walls.
It is recommended that bedroom doors be placed one inch above the finished floor. Otherwise, air flow return to the conditioning unit could be inadequate.