Following a hurricane, damages to a residential structure can range from structural distress, to small areas of mold growth to a total loss of the structure. Storm damage can affect multiple components of a structure including the roof, windows, siding, foundation and interior finishes. Wind or water is often the most common cause of damage to residential properties; however, there are many factors to consider when assessing the various causes of damage. Some of the factors include material use, age, condition and construction methods as well as type, location and extent of the damage. It is essential that a professional with hurricane damage assessment experience evaluate these factors to accurately define the cause. Depending on the extent of the loss, the necessary professional may be an engineer, fire investigator or environmental professional.
In the weeks following a hurricane, other issues potentially affect the damage to the structure. Factors such as extensive mold growth, material deterioration and fire could change the condition of the structure from its post-hurricane state. Standing water, high humidity and warm temperatures create a perfect environment for mold growth. Prolonged exposure to weather and human factors may also cause increased damage to the materials and structure.
One of the most common comments an adjuster hears after a catastrophic storm event is: "My house was not like this before the storm." In large measure, that is generally a true statement regarding the nature and extent of the distress for homes along the primary path of a storm where wind and water forces are the greatest. As one moves towards the outer fringes of the hurricane force winds and storm surge, the nature and extent of wind and water damage should be less. This assumes that all the structures were built according to local building codes and properly maintained. Homes that were not designed or built according to the building code or weakened by aging and weathering will be more vulnerable to damage at thresholds below hurricane force winds.
When the nature and extent of damage present following a hurricane is not consistent with the reported wind speeds or storm surge, it is possible other factors such as pre-existing conditions from faulty construction or a lack of maintenance may be present.
The best indication of the conditions present before a storm event can be provided by photographs taken prior to the storm or recent inspections and/or repair receipts. Homeowners should be encouraged to take photographs of their homes prior to an approaching storm to assist them in documenting storm related damage.
Property condition reports from the most recent sale/purchase of the home are also helpful. After Hurricane Rita, a homeowner experienced a severe crack with both vertical and horizontal displacement in the concrete slab foundation that was being claimed as wind damage. An elevation survey showed that the foundation had settled in the direction of a row of large trees and voids were present along the lowest portions of the foundation. The initial indication was that the crack was due not to wind but to progressive foundation settlement over time. The homeowner provided a copy of the FHA report from an inspection just prior to the storm that reported a hairline crack. It was determined that the pre-existing crack had been exacerbated by the wind forces.
Very few houses are maintained in such a way that they have no conditions of distress as a result of normal aging and weathering -commonly referred to as "wear and tear." Such conditions include cracks in the interior and exterior wall finishes, doors and windows that do not close properly, water stains, leaking pipes, ceiling stains and cracks, uneven flooring, out of plumb walls, loose siding, appliance failures, roof leaks and chimney tilting.
When such conditions are found following a storm event, it is a natural reaction for a homeowner to claim the conditions did not exist before the storm, particularly when the homeowner may not have noticed them until after the storm. A common example is a crack or separation filled with paint from the last time the house was repainted. Following Hurricane Rita, a Texas homeowner filed a claim citing cracks in exterior brick veneer. However, a close inspection of the cracks revealed the cracks were partially filed with mortar from the time the brick was laid.
Regardless of the claims being made, there are items of distress that may be present after a storm event that cannot be reasonably attributed directly or solely to the storm without a closer examination of the nature and extent of the distress, the material conditions and the direction, type and magnitude of force required to cause the distress. Following Hurricane Charlie, a Florida homeowner told the inspecting engineer that his swimming pool enclosure was "not like this before the storm." When informed that the purpose of the inspection was to measure and document the existing conditions and evaluate them for recent movement, deflection or failure of structural members, the homeowner commented that had he known about the inspection, he would have taken a sledgehammer to the anchor bolts. In most cases such attempts to mechanically enhance damage fails due to the person's lack of knowledge of engineering, physics and material science.
Distress may also be the result of a prior loss event, or a material, installation or design defect. Determining the scope of repairs that can be attributed directly or indirectly to a storm event requires expertise in the fields of building design, engineering and construction. Depending upon the nature of the distress or failure, a civil, mechanical, electrical or environmental engineer may be required.
A common installation defect for laminated style shingles on steep slopes that is often claimed as wind damage is actually due to improper nail placement. By placing the nail too far above the nail line, the nail misses the bottom tab. Over time, the adhesive strip between the bottom and top tabs will fail and the bottom tab will slide down out of position. In this compromised condition, the shingle will be vulnerable to future wind damage below the performance threshold of 60 mph.
The misplaced nail is also more likely to be overdriven through the upper tab if the pressure on the nail gun is set for penetrating two layers of shingle. Once the nail head punctures through the top shingle, the shingle has no resistance to wind uplift and is more prone to damage.
With hurricane damage to roofs, windows and walls, water infiltration becomes a serious issue. Water infiltration, massive flooding and high humidity create the perfect environment for mold growth. Growth is further enhanced if the power is out and the space is not air-conditioned. If it goes undetected or no corrective actions are taken, the loss associated with mold can grow significantly. The areas most vulnerable to mold growth are gypsum wallboard materials, insulation and carpet. In evaluating the extent of mold damage to a structure, the loss must be examined in a timely manner by a qualified professional. Registration and certification of a mold professional is required in many states.
As a result of Hurricane Rita, the actual wind/water damage from the hurricane was major, but the fact that electricity was lost for several weeks increased the extent of damage. An issue that is often overlooked is the necessity to identify water-damaged materials that do not have visible mold growth. One of the biggest misconceptions is that if you don't have mold growing on building components within a few days, the materials will remain in good condition. With the electricity off for weeks in the non-conditioned, hot and humid environment, mold is very likely to occur even when there are no apparent signs of growth in the few days following the event. Many areas were cleaned of visible mold only to have continual growth in weeks following the storm. Contractors were required to return to the site multiple times to clean or remove materials. The overall cost and amount of downtime can be reduced if all water-damaged materials are identified and cleaned or removed in the early stages following a storm.
Other environmental concerns that affect a loss following a hurricane are asbestos, lead-based paint and hazardous waste. Hazardous waste will generally be associated with spills from adjacent properties or wastewater impacting a structure. A more common hazardous material that impacts damage assessments following a storm is asbestos. Asbestos is a natural occurring mineral that is found in many building materials that are commonly found in a residence or commercial building. Some Asbestos-Containing Building Materials (ACBM) include ceiling texture, wallboard joint compound, flooring, mastics, insulation and roofing materials. A hazard is created from asbestos only when it is airborne. Therefore, damage to ACBM from a hurricane can create potential for exposure. Contact damage, delamination due to water and vibration, as well as abrasion, can create problems-not only a risk of exposure for occupants, but also construction workers or consultants entering the building.
To reduce the risk of exposure, a thorough asbestos survey should be conducted as part of the evaluation process following a hurricane or fire affecting a structure. Many states require that an inspection be performed prior to any repair or renovation work performed on any type of structure, and the EPA requires inspections on all commercial properties prior to this type of work. Asbestos is a highly regulated and hazardous material with high public awareness that should not be overlooked following a major storm event. A certified, licensed professional with significant experience in performing ACBM surveys must perform the survey. In addition, ACBM must be handled, removed and disposed of by qualified firms and workers. Typically, the most vulnerable material to hurricane damage is spray applied ceiling texture. It is a material that is easily damaged and transported by wind and water. In many cases, the material contaminates carpets, furniture and other finishes to the extent that the cost of ACBM removal significantly exceeds the cost of the original repair.
Identifying the cause of damage to a structure following a hurricane can be complex and requires specialized experience. Not only is it important to consider physical conditions present at the time of the investigation, but also it is equally important to evaluate the pre-storm condition of the structure and determine the damage that has occurred since the storm. Timeliness of the inspection will improve the professional's ability to properly analyze the gathered information and offer a sound conclusion.
Ted Cleveland, P.G. is the regional vice president of the Texas Gulf Coast Region and director of Catastrophe Response Services for EFI Global. He has over twenty years experience with multi-disciplined engineering services specializing in environmental and industrial hygiene related projects. Mr. Cleveland can be reached at ted_cleveland@ efiglobal.com.
George N. Eustace, P.E. is a senior mechanical and civil engineer for EFI Global. He has more than thirty years experience in engineering, maintenance and construction. Mr. Eustace can be reached at george_eustace@efiglobal.com
- SIDEBAR -
The Saffir-Simpson Hurricane Scale divides hurricanes in five categories based upon the intensities of their respective sustained winds. The classifications are intended primarily for use in measuring the potential damage and flooding a hurricane will cause upon landfall.
Category 1 - Winds of 74 - 95 mph
No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Also, some coastal flooding and minor pier damage.
Category 2 - Winds of 96 - 110 mph
Some roofing material, door, and window damage. Considerable damage to vegetation and mobile homes. Flooding damages piers and small craft in unprotected anchorages may break their moorings.
Category 3 - Winds of 111 - 130 mph
Some structural damage to small residences and utility buildings, with a minor amount of curtainwall failures. Mobile homes are destroyed. Flooding near the coast destroys smaller structures with larger structures damaged by floating debris. Terrain may be flooded well inland.
Category 4 - Winds of 131 - 155 mph
More extensive curtainwall failures with some complete roof structure failure on small residences. Major erosion of beach areas. Terrain may be flooded well inland.
Category 5 - Winds over 155 mph
Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. Flooding causes major damage to lower floors of all structures near the shoreline. Massive evacuation of residential areas may be required.
(Source: National Weather Service, http://www.nhc.noaa.gov/aboutsshs.shtml)