Set on 17 oceanfront acres, Seapointe Village is considered to be a premier oceanfront resort community in Wildwood Crest, New Jersey. Three condominium towers and 5.5 acres of recreational amenities over a parking structure were constructed between 1986 and 1992. Following completion, the original 70,000 square foot green roof began to leak damaging the structures and vehicles below. Ten years of numerous unsuccessful attempts at repair followed by a lawsuit lead forensic experts to discover an accelerating rate of deterioration and potential for collapse well before the normal end of its useful life. 

The reconstruction plan was to retain the original 1986 Peridian landscape design while complying with new building codes and accessibility requirements of the Americans with Disabilities Act (ADA). The finished green roof construction cost ranged from $8.50 to $14.50 per square foot and covered approximately 5.5 acres. 

The primary design objective was the installation of a new waterproofing membrane for the plaza deck and parking structure. This required the removal and reconstruction of all roof top amenities. Additional 4”-8” topping slabs were required to reinforce the deteriorated parking structure planks. Designing the new green roof elevations to meet the existing thresholds of the three adjacent condominium structures was exceedingly complex. 

The design greatly minimized the opportunities for construction defects by reducing slab penetrations and incorporating redundancy in most system functions, even installing a second membrane under water features and landscaped areas. This involved installing a multi-part hot applied system ¼ to ½ inch over the concrete applied to both vertical and horizontal surfaces to prevent moisture seepage. A drainage mat and root barrier was installed over the membrane to prevent damage from decorative walkways and from plant material in planters. 

Irrigation lines do not penetrate the roofing membrane as they, and control wires and electrical service were installed above the topping slab in the decorative concrete pavement. The irrigation system incorporates advanced water management features, such as volumetric water sensors, to control irrigation operations. 

The drainage system design was comprised of a variety of unique solutions. The growing media systems accept and store surface water for use by the landscape. The growing media on the roof deck are internally drained with percolation rates of between 6” and 15” per hour, resulting in little to no surface runoff. When the growing media reach material field capacity, the system releases excess water into the thin composite drainage boards, and using the slope of the deck, water finds its way into the roof drains. This maximizes water management by storing up to 4” of volumetric water in the growing media profile.

Three growing media profiles were designed to meet the needs of this site. Being located adjacent to the New Jersey shore required considerable agronomic innovation to ensure sustainability of the landscape under airborne salt and hurricane strength winds. Innovative application of emerging technologies included lightweight growing media, contoured structural foam, and sand-based sod technology. New soil laboratory testing protocols were designed to evaluate and understand specific agronomic performance of lightweight materials, which cannot be tested by traditional methods. Weight restrictions meant that traditional construction equipment could not be supported so that conveyers along with motorized concrete buggies were used to place media on the roof.

Local native plants were chosen for their summer color, their ability to minimize maintenance, conserve water, and enhance biodiversity while also adapting in a harsh environment. 

As the parking structure is located below sea level in a runoff restricted water-quality district, the green roof helps mitigate stormwater impacts, allowing the stormwater management plans to meet local code requirements.

The design team has installed a variety of sensors and methods to observe the performance and functionality of the green roof. The data collected will be used to inform future projects.

Seapointe Village restoration project is an excellent example of using new innovative stormwater management strategies that both avoid water seepage while also encouraging water retention to reconstruct a historic green roof.