Facility Manager Log 2021-08-27
Hurricane Hannah made its way through South Texas over the weekend. The storm had wind gusts up to 70 MPH (112 km/h)and torrential rains that reached up to 12 inches (30 cm) in some areas. My first post on Hive was about the building envelope, which is the protection of the building from the outside elements. A hurricane is one of the ultimate tests of a building envelope because of its extreme conditions.
A hurricane can exert a great deal of pressure on a building through wind force. This is a reason why tall buildings are designed to flex in strong winds in the same way that grass is able to remain unbroken in strong winds.
Another concern about hurricanes for commercial buildings are your mechanicals, like HVAC rooftop units or chillers. For the most part, these devices are anchored down rather well to the roof deck. Along with their weight, it is unlikely that they will fly off in the storm. However, there is always the danger that strong winds will drive water into the electrical components. Or, high winds could easily dislodge a poorly closed service door, exposing the unit's internals to the elements. This can result in expensive repairs.
The roofing material of your building will also have a great deal to worry about. Many roofs use a TPO membrane, which is simply a large plastic cover that lies on the roof with heat gun welds holding the sections in place. If any section of the roof membrane gets loose and catches wind, you risk losing the entire system as the wind will inflate it like a balloon and tear it off.
Asphalt systems are another special danger. Asphalt shingles have a tendency to also lift up during heavy winds. Asphalt covers, which are typically tar and gravel, have the added danger of flying gravel getting flung at neighboring structures. I visited one hospital soon after Hurricane Dolly. The Facility Manager mentioned that the winds picked up the gravel from a mid-level rooftop and shot it at the adjacent windows of the building.
Another force to content with is the weight of water on a roof. Most commercial roofs are flat with a slight grade for water to run off. This can pose a problem because larger roofs must sustain the weight of the water as it makes its way down the slope into gutters and spouts. Consider what would happen if the wind is blowing against the water runoff direction. Suddenly that water is building up and taking longer to drain off the roof. Furthermore, stagnant water has a way of finding the smallest of leaks and making its way through them. Hurricane winds are strong enough to slow down large volumes of water from running off quickly. For this reason, the building design must include extra strength to withstand the weight of that water. The roofing material must also be robust enough to resist water seepage into the underlying roof deck.
Coming down from the roof, another danger of torrential rains on the building envelope is wind-driven rain. This is rain that travels horizontally rather than vertically at your building. For the most part, simple painted walls or siding materials will stop water from entering the building. However, at some point you will have penetrations in your wall for nice things like windows and doors. These penetrations will often be the cause of water infiltration in hurricane conditions. Most commercial storefronts are a combination of metal and glass components loosely joined together mechanically with minimal weatherproofing for aesthetic purposes. If you are ever at a store, you will see that there are typically gaps between doors and doors and frames. These do well in your typical storm. These do not do well at all in wind-driven rain. Storefronts and windows can provide years of service with adequate protection from the elements. However, when confronted with powerful winds and wind-driven rain, their flaws become immediately apparent.
Another water problem buildings have during hurricanes is what happens to the runoff. Most modern construction now includes catchment areas to retain water runoff until it can be drained away or pumped out. These are often designed for a standard storm, not a 12 inches of rain storm. Flooding can occur rather quickly if your building does not have adequate drainage. Older buildings typically do not have retention ponds to catch water temporarily until it can be drained away. Floor-level windows and doors are all too easy for flood waters to enter. However, even brick walls are not impervious to floods. Most brick walls have weep holes along the bottom to let out water that gets trapped between the brick and the inner envelope. This can also serve as a way for flood water to enter a solid wall.
Something you might not think about is that if the sewer or drainage system in your area is flooded to capacity, there is always the potential for the system to reverse and begin to flood your building. This doesn't happen often. However, if it happens once, it will happen again. Drainage and sewer systems don't always keep up with surrounding development. The shortcomings come to a head during heavy rains.
Checking your building for hurricane damage is going to consist of looking for wind and water damage. You are going to look for things that are broken by the wind or debris, such as access panels, windows, signs, landscaping, and even doors that got caught by the wind and bent. You will also look for evidence of water damage. You can often inspect ceilings for stained tiles that show where water seeped through your roof. You will check window sills for evidence of water infiltration. You will also check the floor near windows and doors. Sometimes water can seep in and pool on the floor without any obvious signs at the wall penetrations.
Most of the repairs will consist of resealing your windows and doors, replacing ceiling tiles and finding the sources of roof leaks (which are another adventure), and remediating the drywall or other materials that got wet. The goal is to prevent parts that got wet from becoming a breeding ground for mold, which can become a health hazard down the line. Furthermore, trapped moisture can compromise the integrity of your building materials. In many cases you are better off ripping out sections of your walls and rebuilding them. In other cases, you can ventilate and dry sections of the walls, then fill the holes and repaint.
This assessment is merely what you would do assuming your building help up well to a storm. If you had major failures in your building envelope, the damage is going to be obvious and costly. Unfortunately, it then becomes a battle with insurance companies. If you have flood insurance, there will be arguments whether water damage is from flooding or wind-driven rain. There will also be a lag between getting a quote and the insurance company reviewing it and authorizing payment. In many cases, if time is important, you may have to front the cost of repairs and then try to get insurance to reimburse as much as possible. You will need many photos and documentation soon after the damage.
You are often better served by hiring a remediation company. They often deal with insurance companies and have a sense of what is covered and not covered. They will also tend to take extra steps that you might not take but that insurance companies require to ensure no more liability down the line. The main reason you would want to hire a remediation company is primarily for risk management. You outsource the risk to a third party. If something doesn't work, they are responsible. Second, remediation companies often have teams that handle different aspects of the repairs. Handling contractors on your own can save you money. However, your once in a decade experience will result in some things being overlooked and miscommunication between different contractors and subs. As a Facility Manager, it is well within your job scope to handle your own remediation projects. However, that puts full responsibility on you if things don't turn out right. It is better to leave it to people who do the work routinely and have the teams to get it done quickly and effectively.