I went to work in the family commercial construction company in the early 1980's and by the end of the decade had worked my way into the office as a project manager. Commercial construction is entirely different than residential construction. For one thing, everything is engineered - structural, mechanical, and electrical engineers all take a part in the design of commercial buildings. It wasn't long before I discovered the term "100 year storm".
Many structural designs and mechanical designs were based on the 100 year storm (I'm over simplifying for the purpose of this article). Things like concrete foundation design and building structures were based on the worst earthquakes and windstorms of the last 100 years or maybe storm systems/drains were sized according to the worst rainfalls of the past century. You get the idea.
Throughout the nineties I realized we were getting these "100 year storms" with more frequency. After the year 2000 these storms were setting all time records and the discussion heated up about warming trends and climate change. In 2010 Laurie and I decided to build a new off grid home and I included many design features to address the more severe weather conditions we were experiencing in our part of the world. The costs were minimal compared to (after storm) damage costs and we've never regretted our decision to spend a little more money up front.
These features were over and above current International Residential Building codes used by most jurisdictions at the time. Our design features addressed Earthquakes, Wind Storms, Snow Loads on the roof, and Wildfires. In order to keep this article brief I won't go into details on any of the design upgrades but just want to highlight some of the things we did.
Engineering - We hired a structural engineer for $1,000 to help us with code plus all of the following:
Earthquakes - Our house is an ICF house so that means we have 8" concrete walls. Instead of the typical post and beam wood foundation we decided to go with a slab on grade so now we had concrete walls and floors. The Engineer added more rebar to tie the walls and slab together so that it would act as one unit in case of an earthquake. Our roof is a hip roof and he also beefed up the "ties and hold downs" for the roof structure to the top of the concrete walls. Total cost was less than $1,200.
To see my related article on our ICF experience go to ICF Construction
Wind Storms - We chose to have a metal roof for a lot of reasons. Most roofs in this area are metal. That allows the snow to slide off easier than a BUR but more importantly it is non combustible. We had a wildfire here on the property our very first year! We decided to go with a standing seam metal roof, again for multiple reasons one of which is superior wind load. As near as I can tell from my research, our roof will withstand winds over 135 to 150 MPH. The cost was substantial - over $8,000 but keep in mind our roof covers not only the house but a huge attached garage, attached woodshed, attached carport and covered porch. The end result is a roof that is over twice the size of the house itself.
Snow Loads - We average over 60" a year in annual snowfall. No big deal typically, but we decided to address two additional things: A. Unexpected large snowfall of several feet or more or B. Heavy snowfall and then rain. Rain makes snow really heavy and if it is stuck good enough to the roof you can get into trouble. The Engineer simply required stronger trusses which equates to more materials at the truss company but labor doesn't really change. Cost was about $2,500. I also chose to use exterior plywood (no OSB on my house) with a thicker core than code required. Cost for materials was about $600.
Wildfires - We cleared the land around us of trees and I keep the surrounding grass mowed. Our roof is non combustible metal and our siding is Hardi Plank which is not completely non combustible but it is fire resistant. Under the siding our ICF form is 3-hour fire treated foam next to the concrete walls. The only added expense for fire resistance is the metal we used on the underside of the soffit and carport and covered porch ceilings. Most residential fires caused by wildfires occur when embers are sucked into the attic vent holes (bird blocking) and eventually set the roof structure on fire from inside. The total added cost to cover the exposed underside of the carport and covered porch and soffits was $2,100. For a full description on fire prevention measures we used click on this link: Wildfires
It's been pretty well established that building for the extremes in your area have been successful. In Florida they've added stricter measures for hurricanes that have proven to work. In our area storm detention systems are being upsized to hold more water. All along the west coast earthquake standards are enforced. I did a lot of insurance reparation work as a contractor, repairing wind damage, fire damage, and water damage. I believe you will spend a lot less money preventing damage than reacting to it. I went above and beyond "code" because I haven't seen any decrease in severe weather patterns. New "severe weather event" records are being set every year. You can't stop everything Mother Nature may throw at you but you can sure minimize it in most situations. Where you draw the line is up to you, just know there are preventative measures everyone can take to minimize severe weather storm damage.
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