By: Brian Hval
Why are US houses in hurricane risk areas not built to withstand them? I understand the argument about using local resources (timber vs brick) but why are do building codes not insist on stronger structures that can withstand strong winds?
But codes do insist! Engineers constantly evaluate the need for building stronger and safer structures to resist hurricanes and other extreme wind events. But these structures also need to be economically practical.
Past experience forms the foundation of all building codes. There are mandatory requirements for residential construction permits (and associated framing inspections). But codes change with time as more severe weather occurs or better construction methods evolve. A lot of lessons were learned from Hurricanes Andrew and more recently Maria. And building requirements updated accordingly!
Jurisdictions have found that for a small percent increase in cost, homes can easily be made stronger. They are more likely to survive high wind events with little or no damage:
Wind extremes such as hurricanes
Fires such as wildfires
The insurance industry has found small inexpensive changes in design details can greatly strengthen building structures. Stronger homes are more damage resistant. Less damage means smaller claims. Lower claims mean lower premiums. A big cost-benefit to the homeowner that quickly pays for the small cost of improving the structure.
Anchor bolts - spaced evenly around the house perimeter. These tie a wood frame securely to a concrete foundation.
Hurricane clips - metal reinforced roof joists resist the roof peeling off during a wind event. Very simple structural shapes securely connect roof trusses to the framing of the building walls.
Concrete or metal siding - dramatically increase fire resistance as opposed to wood which catches fire or even fire-resistant vinyl which melts!
Metal roofing - improves both wind and fire resistance. In very windy areas the metal roofs are double screwed to prevent them from lifting off the plywood sheathing below.
A good example of how building requirements change from lessons learned comes from the notorious violent winds which can sweep through the Crowsnest Pass in Alberta Canada.
A few years ago a wind storm destroyed a trailer park. The wind rolled the trailers over and over until the entire community was piled up in a huge heap of tin. The loss was staggering even for those who were insured.
This loss triggered a requirement for all mobile homes to be securely chained from the steel frame to a concrete slab poured beneath the home. None have blown away since.
Building standards specify the minimum requirements. Homeowners may choose to exceed these standards. For some, this gives greater peace of mind and may well be worth the extra cost of building it stronger.
But before building it better, check with your local building permit office to make sure they understand what you are trying to do. That way the inspectors and you will be on the same page. No one wants a surprise that may require you to make further costly changes to your dream castle!