Commercial TPO Re-Roof Corrects Ponding Water and Roof Failure at 8-Building Apartment Complex in Charleston, South Carolina

A property owner and investor approached our team after purchasing an eight-building apartment complex in West Ashley, Charleston, South Carolina. The approximately 43,000-square-foot commercial roofing project involved replacing a 20-year-old TPO system installed over an older tar-and-gravel roof and wood decking. With active leaks, widespread ponding water, and deteriorating conditions beneath the existing system, the property needed more than a simple membrane replacement.

Project At-a-Glance

• Roof Size: Approximately 43,000 sq. ft.
• Property: 8-building apartment complex
• Roofing System: GAF fully adhered 60-mil TPO
• Existing Roof: Approximately 20-year-old TPO over tar and gravel over wood decking
• Warranty: 20-year No Dollar Limit warranty
• Project Type: Retail/direct-pay; no insurance involved
• Location: West Ashley, Charleston, South Carolina
• Project Duration: 12 weeks

Challenge: Ponding Water, Active Leaks, and Deteriorated Wood Decking

Inspection of the existing TPO roofing system revealed a fundamental drainage problem: the roofs had no effective slope, resulting in areas of significant ponding water. The aging system was also visibly leaking in multiple locations, creating concerns about conditions below the membrane.

Those concerns became even more urgent just two days before work began on the first building, when a portion of the roof caved in. As the re-roof progressed across the complex, significant areas of rotted wood decking were uncovered, requiring the project to address the underlying roof structure before the new roofing system could be installed.

For the new owner, the challenge was therefore much larger than replacing an aging membrane. The roofing services needed to correct deterioration, improve drainage, and provide a consistent long-term roofing solution across all eight apartment buildings.

Solution: Custom Tapered Insulation and a 60-Mil GAF TPO Roofing System

Our team approached the 43,000-square-foot apartment complex as a comprehensive commercial TPO re-roof. The new system was designed not only to replace the failing roof but also to correct the drainage conditions that had allowed water to pond across the existing system.

Key project steps included:

• Addressing significant areas of rotted wood decking uncovered during the roofing project.
• Installing a custom tapered insulation package to introduce slope and improve drainage across roofs that previously had no effective slope.
• Installing a new 60-mil GAF TPO roofing system across the eight-building complex.
• Meeting required edge uplift requirements around the perimeter of the buildings as part of the new roofing installation.
• Coordinating work across eight separate apartment buildings over a 12-week project schedule.
• Providing the property owner with a 20-year No Dollar Limit warranty on the completed GAF roofing system.

Correcting the slope was particularly important. Instead of installing another membrane over a roof configuration already experiencing ponding water, the custom tapered package created a roofing assembly designed to move water more effectively and help address one of the primary problems identified during the initial inspection.

Result: Improved Drainage and Long-Term Protection Across Eight Apartment Buildings

After 12 weeks of work, the West Ashley apartment complex had a new commercial roofing system designed around the actual conditions of the property. The combination of decking repairs, custom tapering, and new 60-mil TPO addressed both the deterioration beneath the old system and the drainage problems above it.

For an owner who had recently added the property to her portfolio, the completed re-roof provided greater confidence in the buildings’ long-term protection. Rather than inheriting a 20-year-old system with active leaks and ponding water, she now has a consistent roofing solution across all eight buildings backed by long-term warranty coverage.

Trust & Proof: GAF System Backed by a 20-Year No Dollar Limit Warranty

As a GAF CoatingsPro+ contractor, our team installed a GAF roofing system and provided the owner with a 20-year No Dollar Limit warranty. On a project of this scale, the warranty adds an important layer of long-term protection to the investment in the new roofing system.

This Charleston, South Carolina project also demonstrates the importance of looking beyond the visible roofing membrane during a commercial re-roof. From discovering significant deteriorated decking to correcting a lack of slope with a custom tapered package and meeting perimeter edge uplift requirements, the finished system was built around the specific challenges uncovered across the eight-building property.