Storm Resilience and Design
With the ongoing threat of climate change and a global increase in temperature feeding larger and more destructive storms combined with more and more people wanting to be near the coasts, Storm Resilience is a hot and critical field. In many ways, resiliency is still in it’s infancy and it’s old age. So much of it is simply adhering to traditional principles and so much of it is applying new technologies and materials. As a medium sized architecture firm located in a low lying coastal community, we’ve been involved in many projects that involve resiliency in the face of danger.
Flood Resistance
Probably the most common and basic level of resiliency is designing for homes inside of the flood zone. Here is an example of that duality, most of the method is applying (and enforcing) decades old practices and regulation. Regulatory regimes can change greatly depending on your state, so our expertise is primarily in Delaware and Maryland (with a touch of New Jersey where we rely on specialists a lot more). The major method of providing resilience to flooding is raising the homes. Any space below the flood zone (including freeboard which each community can require to bring down the insurance rates for everyone) must be non-inhabitable and all of the materials must be capable of surviving immersion in flood waters. There must be specialized vents that equalize the hydrostatic pressure on each side of the wall to prevent the walls from collapsing under the pressure. In some cases, the structure must be able to resist scour and/or break away under the assault of waves. In rare cases, we’ve even waterproofed the lowest level and reinforced it to act as a dam in case of flooding.
These are relatively simple, but the detailing (and experience in compliance) is important. Failure to design or build it right can lead to large delays in approvals. We’ve had several jobs where we had detailed everything correctly, but the contractor installed the vents too high and the certificate of occupancy was held up for several days until they could relocate them to the correct height. It would get worse if the wrong materials were used or the structural systems weren’t built correctly and had to be removed and replaced.
Flood Mitigation
Most residential properties don’t have a lot of requirements to reduce flooding. This is usually handled with a generic lot coverage requirement. The idea being, to keep the cost of compliance down, as long as you maintain a certain amount of pervious area to allow water to drain into the water table, that is all the town will require. This is not 100% true and getting less and less so, especially in more vulnerable locations. Sometimes we have had to get civil engineers involved to do an engineered water management solution in addition to the zoning limitations.
In these cases, we often find ourselves turning to newer technologies. Dry well systems, pervious and grass pavers, and other methods of removing bulk water from the surface and allowing it to infiltrate into the site easier. These systems have also gone into making existing conditions better. We’ve used them for clients who had bad water management because they got tired of puddles or their inability to grow grass because of the sogginess of the yards.
Resilience in Construction
It gets harder, when you’re trying to harden a structure for resilience against wind and storms. We don’t get tornados often, but we had a run a few years back where a few made some major headlines. We, unfortunately, had to tell a few clients that designing a home to resist the windows of a tornado is unpractical (unless you like bunkers with no windows.) Usually, to resist extreme storms (and sometimes intruders) we turn to safe room style construction. A hardened room, or closet, can provide safety from extreme winds (and with the right communications equipment) intruders. It can even provide safety for data or equipment in case of extreme cases. We designed a safe room in a basement to survive the house (and a 2 ton gun safe) collapsing on it. I wouldn’t want to be inside it when it happened with the lack of kitchen or bathroom and the long term implications of being trapped under the rubble. However, the recoverable items would survive. We’ve also reminded clients that in case of fire, the saferoom may very well become the oven and you would be the potato, so still nothing beats evacuation in some disasters for life safety.
It’s a little easier to provide resilience to a hurricane. You can build a structure with sufficient reinforcement to survive the projected winds and rain of a hurricane. Flooding may be a problem to consider, but the shell can be built to stay in one piece. We’ve done Fortified Home structures and ICF structures which should survive any storms we’re likely to get in our area (thankfully, they have not been tested too badly.) Even with proper design though, they still suffer damage. One of our ICF homes struggled to maintain it’s roofing system because of the way the wind was funneled by it’s shape. Shingles rated to 150 mph were tearing off at no more than 70 (per the weather station on the home) because of the local effects that would be impossible to test outside of a wind tunnel and an extremely accurate area model.
One thing that is important in resilient design is the detailing of openings. Windows and doors need to be rated to take the abuse, or shutters need to be installed to protect them. If a house loses a window, the opening will doom the rest of the structure no matter how well built or designed. These materials cost a fair upcharge, but a lot less than replacing the home. It’s also important to do a thorough inspection of all of these openings after a storm. Many of them may take damage without fully failing, leaving them vulnerable in the next storm.
Economic concerns are the last component of the puzzle of designing for resilience. Having a home or building that can survive a storm with minimal need for repair is obviously great. However, these techniques cost. If it was cheap to build a home to resist a hurricane or a flood, we’d always do it. With that in mind, the more you want a house to do, expect a premium on cost of construction.
