Practical solutions for Impractical Projects
by Mason Knowles
Increasing one’s knowledge about the use of foam plastic products involves more than merely learning about a plastic building product’s manufacture and performance characteristics. To truly understand how a modern material can best be used often requires a look at the innovation of other construction/design teams who have successfully employed it.
Some roofing projects are more challenging than others. Last year, West Roofing (a LaGrange, Ohio, contractor) was asked to bid on re-roofing a modified bitumen (mod-bit) system installed to a scalloped concrete roof deck at Saint Joseph Hospital in Chicago, Illinois. The task was complicated by a number of factors, but plastic spray polyurethane foam (SPF), helped provide an ideal resolution.
The design/construction team faced quite a few possible roadblocks, including:
- the roof section needing replacement was 21.3 m (70 ft) off the ground and only accessible through the building interior;
- there were no anchors to attach safety lines or fall arrest systems;
- the existing roof had to be completely removed because of the saturated insulation and deteriorated roof membrane;
- the windows next to the roof housed the ‘new mothers and newborns’ ward, making overspray, fumes, and odors major concerns; and
- since a hospital never shuts down, working after business hours was not an option.
Many contracting firms would not have considered this project a prime job for bidding. However, West Roofing seized the moment, seeing the opportunity to use plastic spray polyurethane foam (SPF) as a multifaceted solution to several potential pitfalls. First, they had to convince city officials.
Jack Moore, project manager for West Roofing, told the designers a spray polyurethane foam (SPF) roofing system could provide virtually unique benefits, including a custom fit to the unusual scallop shape of the concrete. Plastic spray polyurethane foam (SPF) could also be spray-applied at 76 mm (3 in.) thick to provide the needed insulation, and would not require additional counter flashings or perimeter edge metal. As another advantage, plastic spray polyurethane foam (SPF) generally does not need periodic replacement, but only regular maintenance and a recoat every 15 to 20 years. The team was also ready to remedy potential problems with the removal of the old roof.
Once city officials were convinced plastic spray polyurethane foam (SPF) could meet the new roof’s needs, city officials had to be assured the polyurethane plastic application would not lead to overspray, odor, or fume problems for the hospital and surrounding areas (and that the job could be performed safely).
Moore assisted in developing a comprehensive safety plan that took into consideration hospital workers, fall protection, and securing the area from overspray and minimization of fumes and odors.
West Roofing’s crews installed 18 ‘spider’ concrete anchors to fasten lifelines for fall prevention. They built a special corridor of plastic inside the hospital for the crews to access the roof from inside the building, separating the tradesworkers from the healthcare workers. This also prevented dust and debris from settling in the hospital. Hospital officials escorted the suited workers to the roof access.
On similar jobs, the contractor had performed area and personal monitoring of plastic spray polyurethane foam (SPF) spray applications. Outside a few feet of application, West Roofing knew the permissible exposure levels of fumes and mists were well within safe guidelines for the surrounding area. To protect the crew, personal protective clothing was used consisting of chemical-resistant protective coveralls, gloves, boots, spray hood, goggles, and suitable respiratory protection. Next, they sealed the building itself to prevent fumes, mists, and plastic spray polyurethane foam (SPF) overspray from getting into the hospital. Windows adjacent to the roof were sealed with plastic ‘shrinkwrap’ (i.e. a 0.15-mm [6-mil] polyethylene film) and spray adhesive.
The crew then tackled the issue of overspray protection for the surrounding area. The project was located right next to an extensive city parks system, with many parked cars and pedestrian traffic. Since keeping the lightweight plastic spray polyurethane foam (SPF) and coating from drifting onto parked cars and passersby was important, West Roofing decided on two types of overspray protection. For the majority of the plastic spray polyurethane foam (SPF) spraying, a movable, custom-designed booth was fabricated to precisely fit the curve of the scalloped roof. The crews sprayed inside the enclosure, effectively preventing virtually any plastic spray polyurethane foam (SPF) overspray from drifting beyond the target area. When they came to the edge, a hand-held windscreen was employed.
A crane was used to lift small containers of tear-off construction debris from the roof to a container adjacent to the building. Within 10 days, West Roofing had performed the tear-off, substrate preparation, plastic spray polyurethane foam (SPF)/coating application, and cleaned up the site, leaving the hospital with a high-performance, energy-efficient roof system. The project’s speed was greatly appreciated by the hospital since it minimized inconvenience. Even more importantly, there were no reported plastic spray polyurethane foam (SPF) overspray claims or complaints of odors or fumes from the plastic foam application.
As a result of these efforts, West Roofing won one of the Spray Polyurethane Foam Alliance’s (SPFA’s) 2006 Excellence in Contracting Awards.
About the Author
Mason Knowles is the executive director of the Spray Polyurethane Foam Alliance (SPFA). He can be contacted via e-mail at firstname.lastname@example.org.