Mexican Beach Developers

by John Fleming

During the 27 years I've been in the real estate business in Tucson, I've watched various building materials come and go, and then come again. The changes are usually based on the price of lumber. If lumber prices are high, builders begin using masonry--adobe, slump block, concrete block, or brick. If lumber prices are low, the business resorts to wood frame with stucco finish. The trend now is away from block; builders are becoming more experimental. They are using alternative materials or combinations: poured concrete, combination foam and cinder blocks, steel frames, rammed earth, straw bales, multi-material panels. It's not just the price any more; speed of construction is also important. Time is money.

Poured Concrete

Both Mexico and the U.S. have been using poured concrete construction for years. Many commercial projects in the U.S. are built with "tilt-ups," slabs of reinforced concrete poured flat on the ground, then, when set and cured, lifted into vertical position with a crane and bolted to a steel superstructure as walls. In Mexico, one of the world's largest users of concrete, government-built housing projects are developed by using poured concrete construction. Forms are bolted together in place to outline a shell, and the concrete is poured between them, making walls. When they are hard, the forms are unbolted and taken down. The same technique is used for the roof. This is a very rapid and cost-effective method of construction. Materials are readily available and cheap. But because concrete conducts heat or cold rapidly into the interior of the house, it's necessary to do some furring-out or insulation to make the building energy-efficient.

Combination Blocks

New, lighter concrete blocks are being used in both the U.S. and Mexico. By using a combination of concrete and styrofoam, material designers have been able to increase the insulation factor and decrease the shipping and construction weight, thus cutting down on costs and adding to the energy savings.

Steel Frames

Steel has been used in the U.S. for industrial construction for generations, but now it is being used in residential projects as an alternative to wood framing. It's rot-proof, termite-proof, warp-proof, crack-proof, fire-resistant, and earthquake-proof. There are no glues and resins in it; no toxins for termite protection are necessary; and 66% of the metal used is recycled, so it's environmentally friendly too.

Rammed Earth

Rammed earth goes back over 4000 years. It was used in ancient China and Egypt, but is a relatively recent development in Southern Arizona. Earth is packed into vertical forms and pounded down, making strong, thick walls (18" - 36") that shut out sound and provide excellent insulation. This material, because of its thickness, can produce an attractive sculptured effect. Serenity Baptist Church on Ajo Highway at Robles Junction (Three Points), Arizona, just outside Tucson, is an example of rammed earth construction. It was built about 10 years ago.

Straw Bales

Straw has been a building material for thousands of years. It's what's left of wheat, rice, barley, or rye after it is threshed to get all the edible seeds out. In many parts of Europe and Asia homes built from straw bales are still standing. In England straw was used for thatched roofs or mixed with mud to make a kind of mortar. The distinctive design of half-timbered houses was produced by building frames with timber about 2 feet apart and filling in the intervening spaces with a mixture called wattle-and-daub made of twigs and straw mixed with clay or mud. Biblical students will remember that the Israelites in Egypt used straw to strengthen the bricks they made until Pharaoh stopped providing it.

Straw bale construction in the U.S. originated over 100 years ago in the Great Plains. There were few forests to produce timber, but tens of thousands of acres of grain made straw a plentiful material. When baled, straw can be readily used for building. Bales come in different sizes, but a typical bale might be 23" x 16" x 45" and weigh 60 to 90 pounds.

The so-called Nebraska House uses straw bales as its structural components. They are stacked like bricks and pinned to a foundation slab with rebar, making them strong enough to bear the weight of the roof without the need for posts and beams. Because of the thickness of the bales, the insulation factor is incredibly high--it may be as much as R-55, compared to R-19 or less in a typical frame house. After the bales are in place and the roof put on, the walls are plastered with stucco inside and out.

Straw lends itself to a sculptured look. Utilitarian slots for wiring or plumbing can be cut in the bales with chain saws or weed-eaters, as can decorative niches for statuary. Corners can be rounded. Windows can be set near the outside walls to produce wide window seats inside. If properly built, a straw bale house will last for years with virtually no risk of fire, mildew, or insect pests. Straw is a very poor conductor of heat, so the temperature inside stays stable. Air conditioning or cooling is rarely necessary. Some straw bale houses are constructed with a wind tower in the center to let the warm air escape upward.

3-D Panels

A company in Mexicali is making what are called 3- D panels; each panel has a core of polystyrene flanked with mesh wire and connected with galvanized truss wires. They come in 2", 2.5", and 4" thick 4' x 8' panels, but other sizes may be ordered. They are inexpensive and lightweight, only 38 pounds per panel, permitting rapid erection of walls with only a few laborers. A 2500 sq. ft. 2-story shell was put up in one day with this material. Once erected, the walls are machine-sprayed on the interior and exterior with a concrete product called shotcrete to a thickness of 1.5". The R-factor of a 4" wall is 18. These panels meet all VA, FHA, and HUD thermal requirements.

3-D panels are environmentally friendly; they are made with recycled steel; the polystyrene core does not deplete forestry products and does not contain chloro- fluoro-carbons. Buildings made with these panels are remarkably strong, having withstood an earthquake measuring 6.9 on the Richter scale in California and Hurricane Andrew in Florida .

Conclusion

For years the U.S. auto industry did a lot with the exterior of their product and very little under the hood. Sharp fins, smiling grilles, sleek bodies, chrome strips were the mind-massaging message. Similarly the floor plan, carpeting, tile, paint color and decorative trim were the song of builders. Underneath the materials were still the same--lumber and masonry. But now more sophisticated buyers are looking behind the walls. They're demanding faster construction, better insulation, more energy- efficiency, greater concern for the environment. Those builders that respond with the most for the least and deliver with efficiency and speed will get the business. And the consumer will benefit.