Taos is as diverse in its types of home construction as it is in the many types of people who live here. The relatively mild, arid, sunny climate that makes Taos such as great place to live also lends itself perfectly to many types of alternative building materials and designs. Some designs are what is known as environmentally sustainable with as little impact on the surrounding landscape as possible. Pushing social consciousness still further some designs deal with the conservative usage of natural resources both on-site and in the building materials used as components in the structure as a whole.
With the increasing awareness that Earth is a fragile living organism and that our resources are indeed finite we should all try and do our part to keep it (and us) as healthy as possible.
The longest wall of the home should face south. The winter sun rises South of East and sets South of West. Placing more glass on the South wall will ensure that your home receives free solar energy. This same orientation helps to prevent the high summer sun from entering the home.
A compass will point to magnetic North/South, but a solar home or collector works best when it faces TRUE SOUTH. Also consider that buildings or trees too close to your home could block the low winter sun.
The amount of glass on the South wall may equal 7% of the homes total square footage. (Example: 2,000 Sq. Ft. = 140 Sq. Ft. of glass.). To avoid overheating, this amount of glass should not be exceeded. The 7% applies to conventional home construction with standard floor coverings such as carpet, vinyl, tile, or wood. Increasing glass area above 7% will require additional thermal mass, i.e. concrete/tile floors, rock, brick,concrete or adobe walls. East and North glass should be limited to no more than 4% of total sq. ft. West glass should not exceed 2% of total sq.ft.
Plant deciduous or evergreen trees on the east, west and north sides of the home. Xeriscape!
Avoid dark colors, inside and out.
Insulate exterior of slab/foundation with extruded polystyrene sheets. R-5 for moderate climates, R-10 for colder climates. Install sill sealer under the bottom plate of all exterior walls, on both the first and second floors.
In moderate climates use 2X4 frame walls with R-13 batts and R-4 rigid insulated sheathing boards (1" expanded polystyrene). For Cold climates, use 2X6 frame walls with R-19 batts and the same R-4 sheathing. Sprayed cellulose insulation should be considered because, though more expensive than batts, is more effective because it fills voids and reduces air leakage. Prior to installing wall insulation, use cans of expanding foam insulation and/or caulk to seal all electrical and plumbing penetrations, around doors and windows. Insulate walls surrounding furnace closets and seal return air plenum.
Ceilings should be insulated with R-30 insulation, blown in type is preferable, for moderate climates. Levels of R-38 to R-50 are recommended for colder climates
Tape/seal all joints in ductwork. Duct work should be installed in interior (heated) space so that heat or cold is not lost to unheated spaces (attic). Furrdowns should be sheathed and sealed prior to installing duct.
Place and size windows to take advantage of natural ventilation and prevailing breezes. Use ceiling fans to keep the air moving and help with heat distribution.
The oldest existing structures in the southwest are built with adobe blocks and these include both homes and missions. The reason that early settlers built with the earth was because this was the only plentiful building material. There were no forests or large quantities of rock available so they built with what they had. Although most of the homes built by their owners were adobe, it wasn't the material of choice but rather necessity. The adobe became the "poor man's" home. Whole families participated in mixing mud in pits with their feet and then pouring the mud into wooden forms.
The adobe is a brick, which is made from mud. The traditional adobe block is 10"X14" and 4" thick. The ideal mix of materials is approximately 20% clay and 80% sand. These materials are mixed with water and the mud is then poured into forms to shape the blocks. The form is removed as soon as the block will retain it's shape and the brick is left to dry in the sun. In a few days the brick is turned on its side to speed up the drying time and within a few more days it is ready to be moved and stacked. The brick reaches full strength, (cured) after 30 days, the same time as concrete.
Straw is often thought to be an integral component of the adobe block but it is used today only by those trapped in tradition, or when the sand to clay ratio is radically altered. Early adobe builders added straw to their mix when large cracks developed in the adobe bricks as they were drying. It was believed that the straw provided strength and with the addition of the straw, the adobes didn't crack. It turns out the cracks are caused by too much clay in the mix. When the proper amount of clay is used, there is no need to add straw. The use of straw should be avoided since it is a food source for insects.
Although the basic sand to clay ratio remains the same, another material is being added to the mix; asphalt emulsion. Asphalt emulsion is an oil by-product commonly used in road construction and when mixed with the water and then the sand and clay, the end result, depending on the amount of emulsion used, is an adobe which is either water resistant (semi stabilized), or totally water proof (fully stabilized). There is some debate about the need for asphalt emulsion. Since the exterior walls of most adobe homes are finished with a cement plaster, a waterproof adobe is not necessary. For an exterior patio or courtyard wall, the addition of the emulsion makes sense.
RASTRA® is a concrete form system made of a lightweight material called THASTYRON, which provides a permanent framework for a grid of reinforced concrete that forms load-bearing walls, shear walls, stem walls, lintels, retaining walls, and other components of a building.
THASTYRON offers the ultimate in properties for a wall, such as insulation, soundproofing, fire protection, all in one easy-to-install element. THASTYRON is also resistant against frost and against heat radiation. It does not entertain mold or attract nesting insects. 85% of its volume is recycled post-consumer polystyrene waste.
Rastra® is an insulated concrete form system made in the United States of a lightweight material Thastyron, a mixture of recycled foam plastic, and a cementitious binder. Thastyron, combined with the structural integrity of the concrete grid and its flexibility, provides a permanent framework for a grid of reinforced concrete to form load-bearing walls, shear walls, stem walls, lintels, retaining walls, and other components of a building.
Concrete poured into the cavities of the elements provides excellent strength. The channels inside the elements have been designed to provide optimum strength while using the lowest possible amount of concrete. The square grid allows use of the elements either vertically or horizontally, maintaining the grid and the runways for reinforcement. By using different strengths of concrete and various amounts of reinforcement, the load capacity can be adapted to any requirement.
The Standard element has an area of 12.5 sq ft and is generally used for walls; the End element is used for ending wall-sections, members of headers, sills and corners. Rastra® elements can be easily cut, rasped, routed or even carved into sculpture-like forms, using common tools for working with wood. Plaster adheres well to the face of Rastra® elements without any preparation, tiles can be glued right onto the surface.
Rastra® elements are molded in a special process. The spongy raw material used to make Thastyron is compacted by applying a certain amount of pressure before elements are set upon a pallet for curing.
The Rastra® elements are cut to exact dimension after they have been cured. This guarantees small tolerances and straight and even walls. Even the production process is designed to protect our environment. As no energy is used to cure the elements, on average less than 2kWh is needed to produce each Rastra® element. During production, no byproducts are set free which may be considered a burden for the environment. All debris from trimming the elements is immediately recycled and made into new product.
Pumice-crete is a low-density concrete made from pumice aggregate, portland cement, and water. It is a mix that succeeds in providing structural strength and insulation in one material. Being lightweight pumice-crete is relatively easy to install and is cast on-site. Typically it is poured in wall thicknesses of 14" or greater and no additional insulation or structural components are necessary. Wall surfaces are finished by applying plaster coats on the interior and exterior, which further aid the thermal performance by trapping air within the honeycomb pumice-crete mix. The walls are very durable, fireproof, have good noise resistance, and are very aesthetically pleasing because they can be formed to fit many architectural appearances and styles.
Pumice is a lightweight volcanic rock that is found in many parts of the world where volcanoes are present. It is a sponge like material formed by expansion of gases while molten lava rapidly cooled. It is a porous glass froth that is found in very shallow deposits in such places as New Mexico, Arizona, California, Oregon, Washington, and Idaho. It is an inert material and therefore has no reaction with any of the ingredients of concrete and steel.
Pumice aggregate is mixed with only enough cement and water to produce a light concrete with a cured strength of 400 PSI. Only enough cement is used to coat the aggregate and bind it together where it touches. This is a lean mix and no attempt is made to fill the space between the stones. This makes for a honeycomb like material with an evenly coarse surface. For most one and two story applications this is adequate structurally and self-supporting with no need for additional support members. More cement increases the strength but reduces the thermal insulating quality whereas less cement increases the thermal insulating qualities but reduces the structural adequacy
Pumice-crete is mixed, either at a central plant and delivered in standard mixer trucks, or right on site, and poured into forms. It is always used over a concrete footing or slab and once the pour reaches roof elevation another structural concrete bond beam is poured that has connectors to fasten the roof system to the walls. Once poured the forms are removed and the rest of construction takes place. Walls are plastered with two coats of any kind of interior and exterior plaster to finish. No further insulation is used in finishing. Stucco netting is not required to adhere plaster surfaces to the wall because of the uniform coarseness of the poured wall.
Walls are poured to a thickness of at least 14 inches to obtain adequate thermal protection and structural integrity. Windows and doors and all openings are defined at the time of pouring and the pumice-crete pours around them as the pour progresses. 2x wood frames are installed in the pour to define the rough opening of the windows and doors. They are formed in such a way that once the forms are removed all the openings have been installed and shaped to their final appearance. Only minor shaping needs to happen before the final plaster coats go on.
Pumice-crete has proven to be a cost effective, reliable alternative to conventional building methods. It is a system that uses no manufactured materials since all components are usually locally available and assembled at the site of construction. It is an earth-based material that is very compatible with adobe styles of building.