J Ferg Roofing Pros – SPF Roofing
Closed Cell vs. Open Cell Foam
SPF Roofing Installation involves different procedures based on the existing roof structure. It is important to be familiar with all state and local building codes. This is to assure the appropriate materials and procedures meet the necessary requirements in your area.
Roof Service Preparation
The proper preparation of the substrate, as well as professional application of the foam and elastomeric coating. This is certainly the most important process in achieving a successful SPF roofing application. SPF requires a clean, dry surface, free of contaminants, for proper application and adhesion. Often a re-roofing application will involve removal of some, or even all, of the existing roof
system to provide a clean surface to apply the SPF. Existing SPF systems will more than likely need to be cleaned, primed, and recoated every 10-15 years. If the roof has been maintained properly, then a quality SPF roof can last up to 50 years or even more.
Once the surface has been properly prepared for SPF application. The “A” and “B” components (isocyanate and polyol resin) are pumped from separate 55 gallon drums, then placed into a specially designed proportioning machine. The materials are heated to a specific process temperature and proportioned to the correct ratio. The two liquid materials are kept separate until they pass through the machine, then through the heated hoses and out to gun. That is where they are finally mixed and sprayed onto the substrate. The SPF is applied to a specific thickness defined by the specification. SPF is typically applied in half inch to one inch layers, or “passes.” Roof specifications or sloping designs that require more foam are applied in multiple passes. The SPF is sprayed down as a liquid, then quickly rises in seconds, and can be walked on in minutes.
Spraying foam requires at great deal of training and experience. This is to assure the proper mixing of the foam is being achieved while maintaining a high level of productivity and quality of workmanship. Most companies in the industry provide this training to new and intermediate contractors.
Proper weather planning is also a must. Although, there are many systems available to meet the various climate conditions. Like most other roof systems, SPF cannot be applied onto a wet or damp substrate. This is because the adhesion will be jeopardized and the potential for failure is almost definite. Be sure to check your weather forecast for rain before starting the job.