Tuesday, Nov 19, 2019

Hurricane ready?

Many years ago, I was designing a small bank branch and the security expert for the bank and I were discussing some of the issues we would deal with. I mentioned the bulletproof glass we would need and he laughed.

“There’s no such thing as bulletproof glass,” he said, “It’s just a question of the caliber of the bullet. We use bullet-resistant glass.”

Since the destruction of the northern Bahamas by Hurricane Dorian, I have been asked by friends and business associates how to build a hurricane-proof house. My answer is usually that I don’t think there is any such thing. There are, however, houses that are more able to withstand hurricanes than others. It is certainly worth considering the features that affect the ability to withstand hurricanes.

The roof

By far the most important feature of the hurricane-resistant house is a roof that will not fail when subjected to the powerful impact of high-speed winds, by uplift forces created by those winds or by flying debris. Once the roof fails, there is no protection for the contents of the house (including the people), which may be sucked out into the powerful swirling winds. The building code focuses a lot of attention on both the structure of the roof and on the ways in which it is secured to the walls of the building. It requires a secure fixing of the roof structure by attaching it to a plate with metal straps or clips and securing the plate to the walls, either by bolts (in a concrete building) or by metal straps (in a wooden house). Of course, the walls themselves must be secured to the foundations either by concrete tie columns or by bolting wood walls to the foundations.

After a previous hurricane, it appeared that roofs with a higher pitch showed less damage, suggesting that the reduced exposure to uplift forces may have been a reason our forefathers built high-pitched roofs. The bonus, of course, was the livable space in the roof.

Finally, the least obvious lesson from our past is the depth of the overhang. The traditional design left little “handle” for the uplift forces, unlike the wide overhangs popularized by photographs of western and U.S. modern houses.

Openings

More than any hurricane in modern memory, flooding has been the cause of death and destruction from Hurricane Dorian. There may be ways in which that storm behaved more like a tidal wave or tsunami because it raised water levels well above anybody’s wildest imagination. While it is unlikely that similar levels will become normal, the fact is that flooding is a real concern. Regardless of the extent, the building must still address keeping water out.

Preventing water driven by howling winds and driving rains from flooding the interior of the house is the job of the design of the doors and windows of the house. Of course, failure of the openings also invites the powerful winds of the hurricane inside, inviting destruction from within as contents are sucked out and the roof comes under pressure from both inside and outside. So the design of openings is critically important. They must be designed to protect the inside of the house.

In the past, houses were designed with a variety of shutter types. They absorbed the wind pressure as well as the forces of flying debris. Where those shutters have been left off, the job of responding to these forces falls to the choice of windows and doors. In the recent hurricane, windows that either failed or were sucked out are evident.

Could floodwaters have been kept out? Who knows? What we know is that windows and doors designed to fit into their openings with a positive seal and unbroken glass panels create a secure interior. Obviously protecting the glass makes the most sense. In other words, while it may seem unbelievable, it is conceivable that a building with secure shutters and doors and well-sealed doors and windows could remain almost dry, even when the house is underwater.

Escape

In public buildings there is a requirement for a second means of escape in case of an emergency. This is not a requirement for a house, but for most people, it is a good idea. The difference between the public and the private consideration is that the method for the public must be controlled for all kinds of people. The family may choose its own way to get out. Whether the solution is a balcony on the upper floor, a dormer in the roof or a removable skylight in the attic, a second escape route is appropriate. The family should address the possible need to get out of the house if their primary route is compromised.

These are simple, common-sense approaches to climatic design, not special design that arise as a result of a single hurricane. We live in a hurricane zone. Once upon a time, we lived in houses designed for that purpose. Whether we lived in a four-room clapboard house or a mansion, we addressed these same issues in our buildings. For whatever reason, we have chosen to ignore our geographic heritage and commit to a high level of vulnerability. Perhaps it is time to return to the principles that got us here.

• Patrick Rahming & Associates is a full-service design firm providing architectural, planning and design services throughout The Bahamas and the northern Caribbean. Visit its website at www.pradesigns.com, design blog at https://rahmblings.wordpress.com and like its Facebook page. The firm can be contacted by phone at 356-9080 or by email at pradesigns@yahoo.com or prahming@gmail.com. The firm’s mission is to help clients turn their design problems into completed projects through a process of guided decision-making, responsible environmental advice and expert project administration.

Latest posts by Patrick Rahming (see all)

FOLLOW US ON:
Shelter migrants fac
U.S. firm assisting