Changes in Traditional Materials
For many years, traditional built-up roofs, composed of layers of roofing felts and bitumen, were the mainstay of the roofing industry.
During the energy crisis of the early 1970s and recent energy concerns, the material used in built-up roofs declined in quality. During refining, more of the petroleum-based chemicals used in asphalts were extracted for use in gasoline and other more profitable items. The content of roofing felts also changed. Felts originally contained natural rag for strength and flexibility. But today, felts contain synthetic fabric and fibers, lowering the performance standard.
Changes in Performance Expectations
Today, it has become common practice to increase insulation thickness to reduce heat flow. With substantial insulation as part of most roofing systems, increased thermal stresses due to membrane heat gain, expansion rates and compatibility are placed on the built-up roof.
Emergence of Liquid-Applied and Single Ply Systems
As a result of changes and performance related issues with built-up roofs, new options became prominent in the market. One new option that has drawn considerable attention is the liquid-applied system – like those developed by Conklin. Seamless, lightweight and highly reflective, liquid-applied membranes have gained momentum and are the product of choice among building professionals. Architects, after years of specifying only traditional built-up roofs, are more receptive to new systems and techniques. Single Ply membranes have also become another choice for many commercial projects due to their ease of application, various methods of attachment, durability and relatively low cost.
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To the roofer, the basic design of a roof is the first factor that comes into play. The roof design is important because it either implies a system that successfully handles the demands placed on it, or one that chronically fails. Most architects and engineers rely on the advice of a select few local roofing professionals when designing buildings. This assures that the design of the roof is executable.
Ideally, each roof design reflects a team approach with the roofer, architect and general contractor working to develop a viable system. Because of the technology and skills unique to each profession, all three parties have input in the final design.
The History of Drainage Problems
In the early 1920s, American architecture became strongly influenced by the Bauhaus School of Design in Germany. This concept called for sleek, severe lines topped with a flat or minimally-sloped roof. While this concept is still popular among designers today, it is considerably less popular with roofers and contractors.
It is a simple fact that this type of roof invites piled-up snow or standing water, placing a tremendous dead load on the roof. If not corrected, the resulting strain can eventually cause the failure of the roof membrane or even the collapse of the entire structure.
When the roofer’s desire for adequate drainage and the designer’s creative concepts are in conflict, it is vital that the roofer find a way to ensure water is shed quickly and completely from the roof. Some of the many ways roofers can accomplish this are described later in the Surface Preparation section.
To solve the perennial drainage problem, the Army Corps of Engineers, Building Officials and Code Administrators, the Department of the Navy, the National Roofing Contractors Association and other roofing organizations have recently endorsed several important recommendations:
- A minimum standard of ¼” slope per linear foot of roof.
- The installation of interior drains. Due to the occurrence of ice damming in freezing climates, scuppers (openings in the exterior wall) are no longer advised. By preventing drainage and causing water to pond, they can create unnecessary or even dangerous dead loads.
- The use of expansion joints, when the decking direction changes.
Other industry standards concerning roof drainage are:
- There should be two drains on every section of roof – in case one becomes clogged.
- Drains should be no more than seventy-five feet apart.
- There should be one square inch of drain for every one hundred square feet of roof.
An adequate slope results in water being directed as quickly and efficiently as possible toward the roof’s drainage system. If a crown or peak is designed into the center of the roof, any scuppers should be spaced evenly around the perimeter to drain the water. Interior drains, incorporating a slope in the central areas of a roof, are also a good way to increase drainage.
One of the best ways to meet all these criteria is for the designer to slop the frame during construction. Other alternatives include spray-in-place polyurethane foam, lightweight insulating concrete and tapered boardstock insulation – all of which can add slope and create a layer of insulation. However, there is a point at which this layering technique ceases to be practical. Due to the multiplier effect of low-density insulating materials, too many layers eventually create an unsound deck.
There are a number of sources of information that provide the knowledge and training to start you on your way as a roofing contractor. Through seminars, magazines, newsletters and conventions, they promote the exchange of ideas and technology among members with the goal of nurturing a healthy economic climate for roofing and construction, and fair standards for labor, workmanship and pay.
The oldest and best known of these organizations is the National Roofing Contractors Associations (NRCA). With a membership of over 2,900 contracting groups, representing all fifty states plus twenty-eight foreign countries, the NRCA is dedicated to the advancement of the roofing industry and serves contractors engaged in the installation of roof decks, coatings, and waterproofing materials. A variety of programs are offered to members, including trade publications, educational seminars, management conferences, safety reports, insurance, technical information and a national convention/tradeshow each February. Membership in the NRCA can be very advantageous to Conklin contractors and is highly recommended.
O’Hare International Center
10255 W. Higgins Rd, Suite 600
Rosemont, IL 60018-5607
Phone: (847) 299-9070
Fax: (847) 299-1193
The Roofing Industry Educational Institute (RIEI) provides objective and current technological information about quality roof design, materials and applications.
10255 W. Higgins Rd, Suite 600
Rosemont, IL 60018-5607
Phone: (847) 299-9070
Fax: (847) 299-1183
The Single Ply Roofing Institute (SPRI) is another nonprofit organization founded in 1982, comprised of manufacturers and marketers of sheet-applied membrane roofing systems.
77 Rumford Ave, Suite 3B
Waltham, MA 02453-3872
Phone: (781) 647-7026
Fax: (781) 647-7222
Spray Polyurethane Foam Alliance
Spray Polyurethane Foam Alliance (SPFA) is a national trade organization which focuses on key issues and events in the spray-applied urethane foam industry. The SPFA holds an annual convention in February to keep foam contractors abreast of technology and other matters if interest. Membership is open to all interested parties.
4400 Fair Lakes Court, Suite 105
Arlington, VA 22033-3801
Phone: (800) 523-6154
Fax: (703) 222-5816
Western States Roofing Contractors Association
The Western States Roofing Contractors Association (WSRCA) has been shaping the western states’ roofing profession since 1974. Their 800 members are educated, professional, roofing contractors and industry related associate members including manufacturers, distributors, architects, consultants, engineers and various other segments of the roofing and waterproofing industry, who are committed to providing the highest quality service to customers.
1098 Foster City Boulevard, Suite 204
Foster City, CA 94404-2300
Phone: (650) 570-5441
Fax: (650) 570-5460
Midwest Roofing Contractors Association
The Midwest Roofing Contractors Association (MRCA) is an association of roofing contractors who have joined together to develop and administer programs and services that help member companies build their business and save them money, while continually working to improve the roofing industry.
4840 Bob Billings Pkwy, Suite 1000
Lawrence, KS 66049
Phone: (800) 497-6722
Fax: (785) 843-7555
Other organizations or importance to new contractors include the local Better Business Bureau and the Small Business Administration, whose purpose is to assist in financing and advertising start-up businesses and to oversee the successful operation of existing small businesses.Ian Myers