If you are someone preparing to build a new house in a hurricane prone region, you may wonder what construction material is the best for a hurricane proof house? When we ask that question we are typically referring to the frame (skeleton) of the home. The decision of what material to use on the frame a home is important, and there are several factors that go into that decision. Those factors include material cost, performance, and ease of construction. For those of us living in a coastal area, the material performance is of particular importance, but the other factors must be examined as well. This article compares two construction materials to build a house in a hurricane prone area. The majority of people will assume that wood is the only choice for residential construction, but I would encourage you to at least weigh the benefits of a concrete or other solution.
When we speak of wood construction, we are referring primarily of conventional wood construction using dimensional lumber and plywood. The frame is built with studs, rafters and joists. Conventional wood construction is either done on site (stick built) or partially in a shop (prefabricated). Examples of prefabricated wood construction includes wood trusses or modular homes built in the shop and delivered to a job site. The modular home industry is growing, and is even marketing itself to the high end housing markets. Other methods of constructing with wood include heavy timber framing, and structural insulated panels.
The biggest benefit to wood construction is its relative cost. Houses can typically be built less expensively with wood than with other material options. This is the primary reason that wood construction is so prevalent. Wood has been around for years, and has proved itself to be a viable building material to withstand the weather. Like any building material, however, when not constructed or designed properly, wood has come up short in the face of Hurricanes. So, it is possible to build a house to withstand hurricane force winds, but some measures should be taken to ensure that it is designed and built properly. An employer once told me that the most important thing to look for when designing with wood was the connections. Connections are king when it comes to wood, so pay special attention to this area. Most building departments require that some engineering be done to ensure that the connections, and other critical items, be evaluated before a permit is issued for the house.
When it comes to performance, there are many benefits to building a house with concrete. Concrete is strong, resistant to fire, decay, termites, and mold. This material is truly sustainable, and that includes sustaining a hurricane. This of course, assumes that the material is designed and installed properly. Concrete construction can be built using either forms, or by using preformed units (aka masonry or blocks).
The most basic method of installing concrete is to build plywood forms, and then pour the concrete walls and floors, which rest on a concrete foundation. The steel reinforcing is placed within the formwork prior to pouring the concrete. Forming the concrete can be labor intensive, and hence cost prohibitive. Insulated Concrete Forms, or ICF are one solution that have been developed to make concrete a more viable option for residential construction. The forms consist of Styrofoam, which is lighter and easier to erect than the plywood forms. Concrete masonry units (CMU) construction, consists of preformed hollow blocks of concrete that are stacked in place, filled with steel reinforcement and then grouted on-site. CMU is also commonly, and incorrectly, referred to as cinder blocks. This method is a widely accepted method in Florida for hurricane proof construction due to its reasonable cost versus the strength that the material provides.
A slight deviation from CMU is AAC, which stands for Aerated Autoclaved Concrete. AAC is a lightweight aerated concrete that is also preformed in standard size blocks, that can be stacked in place, and then filled with steel reinforcement and grouted on-site. AAC is a building material that is relatively new in the US. AAC is gaining popularity because it is lightweight, energy efficient, and is relatively simple to cut and install. I have seen details from the suppliers showing threaded rod systems used inside the blocks, but I would not recommend this practice. Rebar designed to work with concrete should be used inside of the AAC units, and not threaded rods.
I believe that concrete, whether it be formed-in-place concrete or concrete masonry, has inherit strength benefits that will naturally resist hurricane force winds. In addition a concrete option will bring other benefits such as resistance to mold, fire, and termites, as well as energy efficiency. Any of these concrete options will likely be slightly more expensive than wood when evaluated based on initial cost. That being said, it should be noted that the cost over the life of the material, in addition to the up front cost should be considered. For example, a wood home typically costs more to insure than a concrete home. In addition, some states have tax deductions for using energy efficient materials such as AAC. Finally, you must place some value on the higher risk of a wooden home possibly not doing as well in a hurricane as a concrete home.
In making your decision of what material to use to build your hurricane proof home, you will likely compare cost, performance, and other factors. Do not merely assume that what everyone around you is doing will be sufficient for your home. Be aware that there are options to choose from, and it is important to consider which option is the best for your house and your preferences. Finally remember that price is important, but building a house improperly can cost you later.