New Construction Methods in Use in Costa Rica:
For generations, homes in Central America have been primarily made of cement. Sure there's an occasional wood home but Latin America favors cement as the material of choice. It's termite resistant, inexpensive and easy to work with. Unfortunately issues of cement include the high cost of transporting materials, limitations in design (interior walls need to be located above a bearing wall below) and the poor insulation quality and therefor the high usage of energy needed to cool cement homes. Cement block construction (CBS) creates a large heat sink. As the sun shines on the structure all day, it absorbs heat, requiring high inputs of Air Conditioning. Come evening, these structures have captured (and retained) all the heat of the day and require large AC systems to cool them down. After hours of cool down, the sun rises again and the cycle starts again. Energy costs in CBS homes are quite costly.
New products have emerged to address these issues. Popular new products include Eco-Bloc, Build-Block and the Covintec system (Panelco). Let's look at each of these systems. Eco-Bloc http://www.eco-block.com/product/specs.aspx and Build Block http://www.buildblock.com/index.html are very similar. Let's look at these two first.
Both systems use ICF foam "blocks" held together by poly spacers that vary in length depending on the size of the cement wall to be poured inside. These blocks act as forms for the cement, are easy to transport and very light weight. Eco-Bloc and Build Block are now being used in high hurricane risk areas like Florida because of their strength but they also provide super insulation qualities. The blocks come to the job site unassembled. Spacers are inserted into the two halves to create a "styrofoam block form". Each "block" is keyed to connect to the block next to it. Much like using Legos, the block wall is created to a height of about 8 feet and each course of block gets a rebar rod inside the form that sits on the spacer that holds the two halves of the block together. Horizontal rebar is laid in as each course goes in, right angle rebar goes in each corner course and verticle rebar is dropped in when the wall is at the desired height. Window and door openings are cut out and blocked in to prevent the concrete from spilling out when the walls are pumped full of concrete. Then a cement truck and boom pumps the wall cavities full of concrete while vibrators ensure all the voids are filled. For multiple stories, a cap is cemented at the top of the wall to hold the floor joists for the second floor and then another 8 feet of eco-bloc forms are assembled again adding rebar, pumping the walls full of cement when the finished height is reached.
We’ve changed our construction methods in the past few years from concrete block to Covintec, another innovative “Green Home” building product. The Covintec system combines a welded structural steel frame for the house with the insulating quality of EPS steel reinforced panels. Covintec comes in 4’x8’x4” thick panels that are welded into the steel frame to which a thick layer of cement is applied, both inside and out. Using this new method, a structural steel frame is welded together. Then the Covintec Panels are attached via welded straps from the steel. The finished wall thickness is the same as with concrete block with the added benefit of over 3 inches of insulation inside the wall cavity. The final finish consists of a gunite cement coating several inches thick on both the inside and outside of the frame and panels. We further finish the interior walls with setting plaster if an ultra smooth finish is desired, eliminating the need for moisture sensitive drywall. We install PVC conduit for all electrical wiring and use a thermo flex tubing for water lines inside the walls, eliminating the need for fittings inside either the walls or the slab.
Covintec eliminates the heat gain of traditional concrete structures and is stronger with less environmental impact. Benefits include structural resistance to hurricane force winds and greater resistance to seismic activity and earthquakes than traditional concrete block. Because it is lighter than block, it’s easier to transport, reduces outside noise and noise between walls, resists humidity and provides 8 times the thermal insulation of traditional concrete block. Because of Covintec’s light weight, it allows much greater design flexibility than tradition block since interior walls don’t need to be placed over bearing walls below. It has been shown to cut electrical bills by 23% to 27% from the reduction of the need for AC. Since it contains no wood it is also not susceptible to wood boring insets like termites. All our homes are pinned deep into the ground in compliance with engineering requirements. Learn more at http://www.covintec.com/en/ingles/productos_covintec_1.html
Chart showing strength versus traditional building products.
Covintec is stronger than concrete in every way due to the triangular design of the steel within the panels. Tabigue Concreto Armado means a poured reinforced concrete wall, block v. bovidilla is a tradional concrete block wall. Covintec will support more than three times the load of traditional concrete walls.