This final report documents the structural improvements made by Star Home Improvement to protect a residential home from flood damage. The project employed dry floodproofing methods—including impermeable walls, sealants, flood shields, and drainage systems—to prevent water intrusion into the garage and basement. The report details the engineering assessment, design standards based on FEMA guidelines, implementation strategies, cost allocations ranging from $8,205 to $17,645, and maintenance recommendations to ensure long-term system effectiveness.
Star Home Improvement received a request from a homeowner to protect her residential property from flood damage. The client's garage and basement become inundated with water during heavy storms due to openings and crevasses in the housing structure. To maintain and improve the market value of her home, the client contracted Star Home Improvement to implement structural changes that would prevent the entrance of flood waters and associated damage.
In response to the client's initial inquiry, Star Home Improvement proposed two primary methodologies for flood protection: dry floodproofing and wet floodproofing. As FEMA (2014) notes, "Dry floodproofing reduces the potential for flood damage by reducing the probability that the building interior will be inundated." In contrast, "wet floodproofing allows flood waters to enter the enclosed areas of the house; if flood waters are allowed to enter the enclosed areas of the house and quickly reach the same level as the flood waters outside, the effects of hydrostatic pressure, including buoyancy, are greatly reduced."
After evaluating both options, Star Home Improvement recommended a dry floodproofing approach as the most suitable solution for the client's property. The approved project budget ranges from a minimum of $8,205 to a maximum of $17,645. The client approved all initial material costs and doubled the budget allocations for labor costs to supplement preliminary planning and assessment. Material costs were increased by 150%, with an additional $3,000 reserved for post-project costs. The revised timeline maintains a four-week completion schedule, which was successfully achieved.
Star Home Improvement established the expected project outcome based on standards cited by FEMA (2014): "The minimum performance requirement for dry floodproofing measures is a space that is protected by walls that are substantially impermeable and resistant to flood loads." FEMA further notes that "a substantially impermeable wall should limit water accumulation of four inches in a 24-hour period." However, the minimum performance requirement can be exceeded with proper planning, design, and materials.
Given that flooding occurs at 2 inches of water accumulation in the client's garage, Star Home Improvement established a goal to exceed the minimum FEMA standards. The project aimed to completely eliminate flooding or reduce water accumulation to no more than 0.25 inch over an eight-hour period. This maximum allowance for water accumulation would prevent the passage of flooding to the basement and reduce the overall potential for water damage in the garage.
The implementation of dry floodproofing required adherence to FEMA's parallel standards, which include: detailed site evaluation; detailed building evaluation; careful evaluation of all dry floodproofing measures; design by a qualified registered design professional; verification or testing that the constructed systems provide the desired floodproofing effectiveness; and development of an operation and maintenance plan. These requirements ensure that the completed system meets both regulatory standards and the client's specific performance expectations.
On October 22, Star Home Improvement's assessment team conducted a comprehensive evaluation of both the site area and the home structure. According to FEMA (2014), "the site investigation will determine if the existing building can be cost-effectively retrofitted by looking at flood conditions needed to calculate the flood loads, such as depth of flooding and flood velocity. The site investigation will also determine whether the existing soil conditions and any existing fill under or around the building could resist scour and erosion during a design flood event."
In addition to site assessment, FEMA standards require comprehensive building evaluation. As documented in FEMA guidance, "The building should be evaluated by a structural engineer to determine whether the exterior wall and floor systems can resist the forces generated by the design flood event. Flood loads can cause wall systems to fail, possibly resulting in structural damage that is more severe than damage from inundation." A primary design consideration in dry floodproofing is therefore the determination of the foundation, floor system, and exterior wall's ability to withstand the forces generated by a design flood event.
If building strength is found to be inadequate, decisions must be made regarding how to achieve the desired level of performance. Options include strengthening existing wall systems or implementing other mitigation strategies such as elevation or structural reconstruction. The costs and obstacles associated with retrofitting an existing building to resist flood loads must be weighed against the effectiveness of alternative approaches.
Following this comprehensive evaluation, the Star Home Improvement team determined that dry floodproofing would be an appropriate and ideal method to protect the home from flooding and water damage. The team would employ "a combination of measures that results in a structure, including the attendant utilities and equipment, being watertight with all elements substantially impermeable and with structural components having the capacity to resist flood loads."
Star Home Improvements planned for comprehensive measures to reduce or eliminate flooding of the home. The comprehensive strategy included continuous impermeable walls, sealants for openings, flood shields for exterior wall openings, and external and internal drainage systems.
The structural team reinforced the current exterior walls adjacent to the garage to prevent flooding within the garage and subsequent leakage to the basement. The team sealed adjacent exterior walls "using technologies that include impermeable waterproof membranes and potentially strengthening those walls." Specialized sealants were incorporated on the garage door to make it more watertight and resistant to flood loads. To further ensure that water does not enter the garage, Star Home Improvement installed a flood shield on the back door entrance to the garage—the primary location where water could enter during a flood event. The flood shield "produces an excellent seal when it comes into contact with a stainless steel mounting plate that is permanently installed around the opening covered."
Finally, Star Home Improvement incorporated external and internal drainage systems to manage any water that penetrates the primary protective measures. The drainage systems represent a "primary method of removing water that may seep through fissures and pathways in the protection system." The installation process proceeded sequentially, with the construction storyboarded through six photographic figures. Figure 1 shows the garage front prior to structural changes. Figures 2, 3, and 4 document the installation process prior to full covering of the system. Figures 5 and 6 display the completed drainage systems in both view angles.
"Annual maintenance and post-implementation monitoring protocol"
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