CRCA - Chicago Roofing Contractors Association

Low Slope Commercial, Industrial, & Institutional Roofing

Low Sloped Roofing, commonly referred to as Flat Roofing, is an industry onto itself. There are thousands of configurations to choose from. There are several roof deck types, insulation requirements, roof membrane requirements and other factors complicating the selection. To simplify the process, a professional roofing contractor should be involved to assist in selection of the appropriate roof system for the particular application in new construction or replacement applications.

Photo Courtesy of
Ridgeworth Roofing
Co., Inc.

Photo Courtesy of
Bennett & Brosseau
Roofing, Inc.

Photo Courtesy of
Dessent Roofing Co., Inc.

There are several types of roofing membranes that are used on Flat Roof Assemblies:

Photo Courtesy of
Jones & Cleary Roofing
/Sheet Metal

Built Up
There are basically two types of built up roofing (also known as BUR). The difference is that either a coal tar pitch or asphalt waterproofing could be used as the waterproofing element between plies of reinforcing felt. There are advantages and disadvantages of each system.

Photo Courtesy of
Coleman Roofing, Inc.
Modified Bitumen
Membranes are hybrids of the built up system, only pre manufactured in the factory. The products come in rolls, and are modified asphalt or coal tar systems with a rubber added for low temperature and elongation characteristics. These products typically use a built up membrane underlayment before application of the final modified bitumen membrane. Modified bitumen membranes can be torch applied, self adhered or mopped in place with hot bitumen. They are always surfaced with some type of Topping System.
Single Ply
Single Ply roofing systems are just that, a single ply of a roofing material made from several types of polymer plastics and rubbers.

Photo Courtesy of
Crowther Roofing and
Sheet Metal, Inc.
Ethylene Propylene Diene Monomer is manufactured into large sheets for application to insulation on a roof. The material can be loose laid and ballasted with rock or pavers to hold the membrane in place. It can also be fully or partially adhered as well. Seams and the membrane are adhered with contact adhesives, with seams sometimes sealed with a sealant. Toppings may or may not be required by the manufacturer in many cases. This product is available in black.
Polyvinyl Chloride Sheets are manufactured into rolls, and typically mechanically fastened to a roof deck assembly. Screws and plates are used to hold the roof membrane to the roof assembly. Seams are heat welded together, and sometimes sealed with a lap sealant. PVC membranes are reinforced with a fabric scrim, and available in tan and white colors. A topping material may not be required on this membrane.
TerPolymer Olefins are typically fleece backed sheet membranes that are adhered with adhesives to insulation. These products are typically white in color, and may be reinforced. There may or may not be a topping system used on these systems.

Photo - E.W.Olson Roofing

Overburden Systems
The roof systems above may require toppings to hold the membrane in place (Loose Laid Ballast, Paver Systems) or small river rock adhered in hot or cold adhesives (Built Up Roofing, Modified Bitumens) or a coating of some type. The Toppings serve to protect the roof membrane from damage, Ultra Violet Light and general abuse.

Photo - Bennett & Brosseau
Roofing, Inc.

Garden Vegetative Roofing Systems
Vegetative Garden, a version of “Green Roofing”, is a relatively new concept in the United States, with Chicago Roofing Contractors Association Members leading the way in Vegetative Garden Roof Applications. Vegetative Garden Roofing Systems, have been used for centuries in Europe as a way to reduce the need for power for air conditioning in buildings, reducing the demand for energy, and the temperature of the city at the same time. Most important, these roofs slow roof water drainage down, allowing storage to take place on the roof, releiving our combined underground sewer and drainage systems during times of heavy rainfall, preserving Lake Michigan.

The 'overbruden' for these vegetative roof systems is either hand placed and layered soil growing media, or pre-fabricated trays, with growing live plants delivered to the roof for placement by roofing contractors to specifications.

Garden Roofs may also meet code requirements for reflectivity of roofing in urban area, reducing the Urban Heat Island Effect, the subject of the 2009 Chicago Energy Code.



Garden Roofing

Garden Roofs are available in two types. Intensive and Extensive Systems are the terms used to describe the systems. View CRCA's Vegetative Garden Roofing project profiles here.

Photo - Roofs, Inc.

Extensive Systems typically use a thin layer of growing media soil and plantings on top of the roof assembly, allowing use on buildings where a ballasted single ply roof system may have been used.  Pre-fabricated tray systems are also provided by CRCA Members as well.

Intensive Systems assemblies use a heavier layer of soil and larger planting including shrubs, trees and other plants.

Photovoltaic Devices – Professional Roofing and Waterproofing Contractors also install devices called photovoltaic devices. These assemblies, when installed on a roof convert solar energy to electricity reducing the demand for power from fossil fuel and nuclear power plants.

Whether Vegetative Garden Roofing, Photovoltaics, for the best in water integrity and expertise, rely on CRCA Members.


How to Select a Roofing & Waterproofing/Dampproofing Contractor

The Characteristics that are important in any service industry selection also hold true with a waterproofing and dampproofing contractor. Important things to consider are:

  1. Is Roofing and Waterproofing/Dampproofing the contractors’ primary business? Does the firm have experience installing the particular materials on the project?
  2. Does the Contractor have an educated workforce?
  3. Is the Contractor Licensed and Bonded?
  4. Does the Contractor belong to the local (CRCA), regional (MRCA) and national (NRCA) trade associations? These associations provide educational opportunities for employees and workers in many topics.
  5. Insurance protection is important to you, the purchaser. Does the Contractor have adequate Workers Compensation, Finished Products and General Liability Insurance as required by local ordinances? Ask for the certificates of insurance and review the coverage and effective dates.
  6. Have you seen a reference project listing of similar projects?
  7. Have you called the local Better Business Bureau?
  8. Did the contractor provide a written proposal?
  9. Have you verified the contractors address, Tax I.D. number, phone and fax numbers?
  10. What kind of Quality and Safety Programs does the firm have in place to protect you and their employees? Do they have any certifications? Is their safety record better than the national average consistently? (click here for information about Safety)
  11. Who will supervise the work?

The questions above for evaluation of a contractor are not exhaustive. Be sure to review bids for work carefully, focusing not just on price, but also on quality and qualifications to perform the scope of work on the particular Roofing, Waterproofing or Dampproofing project.


How to Select a Contractor?
How to Find a Contractor?
Why a CRCA Member Contractor?
Browse the CRCA Member List

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Go Green with a Garden Roof