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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.
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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. |
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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. |
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Photo Courtesy of
Crowther Roofing and
Sheet Metal, Inc. |
EPDM
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. |
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PVC
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.
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TPO
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.
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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. |
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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.
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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:
- Is Roofing and Waterproofing/Dampproofing the
contractors’ primary business? Does the firm
have experience installing the particular materials
on the project?
- Does the Contractor have an educated workforce?
- Is the Contractor Licensed and Bonded?
- 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.
- 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.
- Have you seen a reference project listing of similar
projects?
- Have you called the local Better Business Bureau?
- Did the contractor provide a written proposal?
- Have you verified the contractors address, Tax
I.D. number, phone and fax numbers?
- 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)
- 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.
Links:
• How to
Select a Contractor?
• How to
Find a Contractor?
• Why a
CRCA Member Contractor?
• Browse the CRCA Member List
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