EXTREME Field Test!
© 2004 Door & Access Systems
Publish Date: Winter 2004
Author: Al Mitchell
Pages 46-48
EXTREME Field Test!
Editor’s Note: In this special series of eyewitness reports of Florida’s recent bizarre hurricane-fest, we present independent perspectives from three DASMA companies: Clopay, Raynor, and Wayne-Dalton.
Part III
Riding Out the Storm
An Engineer’s Eyewitness Report of Hurricane Ivan
By Al Mitchell, Director of Research, Wayne-Dalton Corporation
Here in Pensacola, Fla., hurricane season can cause alarm but usually not a lot of panic. However, we had a reason to panic this past September when Hurricane Ivan roared through my town. Ivan did not change my attitude toward hurricanes, but the experience did teach me a few lessons.
A Peculiar Storm
This storm was the worst I have ever experienced. Ivan brought the most destruction, the longest period of time we were under the wind, and the worst storm surge (water rising) effects.
Ivan was a slow-moving storm. When a hurricane forward speed is 20 to 25 mph, the storm will usually pass in a few hours. However, one new lesson I learned is that when a hurricane is moving less than 7 or 8 mph, like Ivan, it seems to last forever.
Category 1 winds (at least 75 mph) first hit us about 9 p.m. on Sept. 15, and they peaked early the following morning around 3 a.m. Hurricane-force winds continued on until that afternoon.
Around 9 a.m. on Sept. 16, I called DASMA Technical Director Joe Hetzel from inside my home using my cell phone. I described what was happening outside, seeing debris blowing down the street. Joe said he could hear the wind howling in the background.
Near the Eye of Ivan
The eye of the storm passed over Orange Beach, Ala., only 20 miles west of my home. I was near the heart of major damage, which stretched from Navarre, Fla., (35 miles east of here) to Mobile, Ala. (40 miles west of here).
Electrical power was lost about 11 p.m. the night the storm came ashore. I was without power for a week, although many areas lost power for two weeks. The water system was breached, so those who had running water had to either boil or add bleach to make it consumable.
Checking Test Doors
Over the last several years, we had placed 47 Wayne-Dalton test doors in this area. Some of these doors were designed for less than the newest code requirements, but the remainder met or exceeded the code.
Almost all of these doors remained in the openings and were operable after the storm. However, three doors close to the beach, of a new design, were missing and presumed to have been destroyed by the 15' to 16' storm surge.
Better Homeowner Preparations
In this part of the country, we have a procedure to prepare our doors for hurricanes. First, we disconnect the power to the operator to prevent damage from lightning strikes. If locks were removed when the operator was installed, we replace them. We then lock the garage door.
If a door has vertical reinforcement as an add-on product, that reinforcement must be installed, making sure all the hinges are properly fastened. Door preparation procedures are normally done while boarding up windows, closing the storm shutters, dropping swimming pool levels, filling bathtubs with water, and locking all gates and doors.
Whether staying or evacuating, thorough preparation is a must. Anything that comes loose during the storm usually cannot be repaired.
My Ivan experience made me think that DASMA should generate a checklist to guide consumers on how to prepare a door for a storm. Beyond that, we could develop a guide on how to assess the condition of the door before trying to operate it after a storm.
At the DASMA Commercial & Residential Garage Door Technical Committee meeting in October, I shared these ideas about homeowner preparations of garage doors. The Committee agreed that DASMA should consider producing these guidelines, particularly if the homeowner doesn’t have enough time to get help from a local dealer.
Questioning Wind Speeds
Another new lesson I learned was relating to the actual winds near the ground versus winds that are reported in the media. I attempted to determine the different wind velocities at various elevations useful to our products.
The National Weather Service commonly measures wind speed at 33' above the ground. However, most of our commercial door products are around 12' to 14' high, and our residential door products are around 7' to 8' high.
Therefore, I mounted wind speed measuring devices at 7', 14', and 33' in the vicinity of a particular door. The wind speed measuring device at 33' failed at 106 mph around 1:45 a.m. on Sept. 16.
The other two continued to monitor wind speed without failure. The 14' device recorded a maximum wind speed of 76 mph at 2:15 a.m., and the 7' device measured 52 mph at 3:10 a.m. Reported winds were much higher than what I measured.
Door Survivors
Inspecting inland neighborhoods not far from my home, I estimate that we lost 3 percent (1 out of every 33 or so) to 4 percent (1 out of 25 or so) of the garage doors in this area. From what I could see, they were all below the code requirements.
Here’s something else I learned. Inland homes built to the 1994 Standard Building Code performed well. (This 1994 code is the predecessor to, and the original model code for, the Florida Building Code.)
New inland homes had little or no damage to any portion of the home. In my opinion, the codes work when they are adopted and enforced by code officials and when they are followed by manufacturers and installers.
Code Contradiction
One final observation. There appears to be a conflict in the building codes pertaining to garage door performance in high winds in coastal areas.
On the one hand, the codes want garage doors to resist wind pressure and wind-borne debris. On the other hand, the codes promote break-away construction in a flood zone, which includes almost all Florida coastal areas. When storm surge causes hydrostatic pressure on a structure, break-away construction relieves stress on the overall structure.
Here’s the problem. Break-away construction is normally designed to break away around 10 pounds per square foot (psf) of pressure. However, the wind load requirement for the door is around 36 psf.
You can’t have it both ways. I believe this matter needs to be resolved in the codes.
I’m hoping I can apply all of what I learned from Hurricane Ivan to my personal property, the work for my company, and the work I’m involved with through DASMA. Living through Hurricane Ivan certainly strengthened my convictions about doing things right … both for our industry and for my own home.