Past Hurricane Damage Observations

During our past work observing hurricane-related damages, we have noticed several important and recurrent issues.  They are as follows:

New Orleans Hurricane Pie Consultants

New Orleans Hurricane Pie Consultants

Slab-On-Grade Foundations –
Many of the homes in the hurricane regions are constructed with slab-on-grade foundation systems. These systems are very susceptible to differential foundation/soil movement unrelated to the hurricane wind forces. There are numerous claims regarding slab-on-grade movement resulting from the hurricanes, which are unfounded based on our review of the forces necessary to move such foundations. Although damage related to differential foundation/soil movement are not related to the hurricane wind forces, these homes can still have damage associated with framing displacements under wind loading.

New Orleans Hurricane Pie Consultants

Washed out bridge

Pier & Beam Foundations –
These foundations are composed of masonry or concrete individual piers that are usually placed 5’ to 7’ on-center in each direction. This was commonly done on older (60+ years) homes in the South to raise the house to combat localized flooding. However, the wood framing members that bear on these piers are not positively attached to the piers (via metal connectors), and thus, the house is susceptible to “shifting” or incremental movements during large wind forces. Also, the grading under these houses is usually very flat or even has low spots, allowing surface water to collect under the houses. Long-term soil differential movement is also a problem with this foundation system because of this type of grading condition.

New Orleans Hurricane Pie Consultants

Damaged home

Gable Wall Construction –
For gable-framed roofs, the gable walls are usually placed on top of the single-story brick veneer, and the 2x studs are then nailed to the adjacent bearing wall and the edge rafters. Unfortunately, the placement of the studs on top of the brick veneer makes the gable wall itself susceptible to lateral movement, especially outward forces against the wall framing. These nails are then more susceptible to withdrawal, with subsequent separation of the gable wall from the veneer and the roof framing.

New Orleans Hurricane Pie Consultants

Damaged building

Missing Intermediate Rafter Bracing –
Many older homes that have 2x rafter framing do not have the metal clip connection at the bearing ends of the rafters, i.e. “hurricane clips.” These clips help resist uplift on the roof system, and are commonly utilized in new construction. However, this was not a requirement on older homes, and so nailing of rafters to the bearing walls, ridge members and intermediate bracing is needed to resist large uplift loads. However, many older homes have missing intermediate bracing due to the installation of some HVAC systems that required the temporary removal of this intermediate bracing. This bracing should be replaced as part of the complete installation of these conditioned-air systems, but many times this re-installation was not done. Consequently, many ceiling joists experienced some uplift, with resulting damage to the drywall ceiling and adjacent walls.

New Orleans Hurricane Pie Consultants

Damaged homes

Vaulted Ceiling Framing –
For homes that are generally older than 20 years, vaulted ceilings were typically achieved with 2x ceiling joists that are nailed at one end to the sloped rafters and then placed on top of an interior-bearing wall. Because of the slope of the vaulted roof assembly, these joists are typically not nailed either to the bearing wall or to adjacent, flat ceiling joists. Therefore, these joists are not fully anchored at the interior end, and once the roof experiences uplift from relatively large wind forces, the ceiling joists also experience upward movement, with some resultant distress to ceiling drywall and adjacent drywall.

New Orleans Hurricane Pie Consultants

Home Washed Away

These are just some of the common items of distress that Pie observed during our site observations to many residential structures after the Katrina and Rita hurricane events.

Hurricane Earl is set to hit the East coast tomorrow…we hope everyone is staying safe out there!

{All photos copyright Pie Forensic Consultants}

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