Why Do Americans Build Houses with Plywood?
When considering the durability and construction methods of houses in the United States, plywood is often a material of choice. This choice is driven by various factors, including the prevalence of extreme weather events and the practical aspects of construction. In this article, we explore why many Americans build houses using plywood, and why such buildings may seemingly “disappear” when faced with extreme weather conditions.
The Extent of Extreme Weather Events
First and foremost, it's vital to understand that the impact of extreme weather events is often localized. While hurricanes and typhoons can be powerful, the area where the most intense wind damage occurs is typically limited. Even in a storm like a hurricane, the area experiencing extreme wind is much smaller compared to the overall size of the storm. This is a critical point to consider when assessing the vulnerability of homes during such events.
Plywood vs. Solid Wood: A Misconception
There is a common misconception that plywood is inherently less durable than solid wood. However, this is often not the case. Plywood, when properly used and protected, can offer excellent strength and durability. Sometimes, the damage seen in a structure after a storm seems to be attributed to the plywood, but what often happens is that the structure fails first, and then the plywood breaks up and looks damaged. It's akin to blaming the wings of an airplane for a crash when the real cause lies in the engine failure.
A Diversity of Housing in the United States
The United States is vast, encompassing a wide diversity of climates, geologies, and cultures. This diversity influences the types of home construction found across the country. For example, homes in Hawaii might not even have furnaces or heaters, while in Maine, homes are almost guaranteed to have serious heating systems. California, where this article's author is from, showcases an even greater diversity, including homes with single-wall construction, concrete poured-in-place, log cabins, brick, CMU (Concrete Masonry Units), steel frame with sheet metal or rigid beam lateral resistance, hay-bale rammed earth, repurposed shipping containers, and traditional wood frames.
Given the diverse range of construction methods, plywood is just one of many materials chosen based on availability, cost, and familiarity. It performs well and is highly cost-effective when properly protected and shielded from the elements.
Understanding Plywood's Strength in Construction
Plywood, when of proper thickness and effectively fastened to correct timber studs, can create a very strong structural system. The author, a 1967 graduate in structural engineering, shares a personal anecdote about a hunting camp cabin built with 3/8-inch plywood on 2x4 studs, fastened every 6–8 inches with nails. This structure weathered 125 mph winds for 2 1/2 hours during Hurricane Michael, with the only damage caused by 18-24 inch pine trees that fell and destroyed the bathroom.
Resilience Against Extreme Weather
Masonry construction, although generally more resistant to wind damage, can still be subject to serious hurricane loads. Metal buildings, though often impervious to rain, can still leak during torrential downpours. Additionally, all types of construction are susceptible to flood damage. In regions prone to earthquakes, such as California, simple wood frame structures with plywood seem to survive the best. Plywood, with its strength and cost-effectiveness, remains a favored choice in many parts of the United States.