CRCA Education Series
Self-Adhering
Membrane
Roofing Systems
for Low Slope
Roofs
CRCA is a Registered Provider with the American Institute of
Architects Continuing Education Systems. Credit earned upon
completion of this program will be reported to CES records for all
AIA members. Certificates of Completion for non-AIA members
are available upon requests.
This program is registered with AIA/CES for continuing
professional education. As such, it does not included content
that may be deemed or construed to be an approval or
endorsement by the AIA of any material of construction or any
method or manner of handling, using, distributing, or dealing in
any material product. Questions related to specific materials,
methods, and services will be addressed at the conclusion of this
presentation.
Learning Objectives
• After completing this course, you will be able to:
– State the definition of a low slope roof
– Describe some of the historical and technical developments in self-adhering
roofing systems
– Describe the components of a self-adhering roofing assembly
– Describe one or more key technical developments of self-adhered roofing
systems
– Describe the principle factors that need to be considered in the design of a
self-adhering roofing system
– Describe the key considerations needed for the successful installation of a
self-adhering roofing system
Low Slope Roofing Overview
• Low Slope Roofs
– These roofs have a slope of 3" per foot or less, according
to the National Roofing Contractors Association (NRCA)
– The minimum slope for a roof, as mandated by building codes,
is 1/4" per foot
– Depending upon a structure's individual design, more slope may be
required to assure adequate drainage and prevent “ponding water”
Low Slope Roofing Overview
Roofing Demand by Building Type
$
Institutional
19%
Other
6%
Office &
Commercial
53%
Industrial
22%
Source: The Freedonia Group, Inc. 2006
Low Slope Roofing Overview
Roofing Demand by Application
New
Construction
20.7%
$1.4 Billion
$
Reroofing
79.3%
$5.4 Billion
Source: The Freedonia Group, Inc. 2006
Low Slope Roofing Overview
Annual Number of Modified Bitumen Squares Shipped
Numbers in (000’s)
SBS
APP
SelfAdhering
Self-Adhering
Underlayment
2001
6,455
6,857
394
6,982
2002
6,762
6,371
690
8,789
2003
7,445
7,022
758
12,084
2004
8,044
7,157
718
15,059
2005
8,335
7,614
941
16,835
2006
8,133
6,656
1,007
17,274
Note: Data from Asphalt Roofing Manufacturers Association - Summary of Asphalt Roofing Industry Shipments for
All Reporting Companies; No information on Self-Adhering shipments prior to 2000.
Low Slope Roofing Overview
• Low Slope Roofing Advancements
– The past 20 to 30 years have seen significant
technological developments
– These developments are the result of the
industry's ongoing research
– Many roof system choices are available for
low slope bituminous roof applications
– Self-adhering modified bitumen systems (or SAMBs)
are one of the most recent roof system developments
Self-Adhering
Roofing Systems Overview
• Beginnings of Self-Adhering Roofing
– Waterproofing – 1960’s
– Roofing - Europe - mid 1970’s
– More recent introduction of higher quality (better tackiness) in Europe in the early
1990s
Carlisle
Grace
Polyguard
Firestone
Technical Developments in SelfAdhering Roofing Systems
• Trends in the MB Self-Adhering Roofing Systems Industry
– Beginnings of self-adhering application
– Early usage – Eave edge, valley underlayment
– Exposed residential add-ons and low-slope applications –
– Porches, “Florida” rooms, carports, breezeways, etc.
Self-Adhering
Roofing Systems Overview
• Entry Into U.S. Market
– Late 1970’s – Early 1980’s –
–Self Adhered SBS / Polyethylene & Foil Sheets – 40-50mil
– Early 1990’s –
–SBS / fiberglass, polyester reinforced, granular surfaced sheets
– Future….
Self-Adhering
Roofing Systems Overview
• Self Adhered Modified Bitumen Roofing Membrane
– 1960’s-70s technological advances in asphalt sciences originating
in Europe led to the development of modifiers
• APP (atactic polypropylene)
• SBS (styrene-butadiene-styrene)
– When added to unblown (unoxidized) asphalt, these impart either plastic (APP) or
rubber (SBS) characteristics
– These additives provide enhanced performance characteristics to
traditional asphalt
– 2007 - Combination Hybrids - Proprietary Blends – New Adhesives
Self-Adhering
Roofing Systems Overview
• Self Adhered TPO
• Hot melt pressure-sensitive adhesive
– 100% solids
– Double-sided release liner
– Rolled, not broomed
• Thicknesses
– 45 & 60-mil
• Sheet sizes
– 5 and 10-foot widths
– 50 and 100-foot lengths
Carlisle
Self-Adhering
Roofing Systems Overview
• Self Adhered TPO
• Seaming
– Heat-welded
Self-Adhering
Roofing Systems Overview
• Self Adhered TPO
• Temperatures
– Install @ 50F+
• Substrates
– Insulations, Plywood, OSB, Gypsum
• Detailing
– Same details and accessories standard TPO
– End laps - welded reinforced TPO overlays
– Angle changes - membrane secured with
fasteners and plates
Self-Adhering
Roofing Systems Overview
• Developments in U.S. Usage
– Self-adhering systems primary uses - application method restrictions:
• Risk of fire
• Environmental concerns
• Smell
• Lack of equipment access
– Specifically….
• Roofing and re-roofing - historical structures
• Other combustible (wood) deck structures
• Healthcare and educational facilities
Technical Developments in SelfAdhering Roofing Systems
• Self-Adhering Roofing Systems
Characteristics
– Environmentally Friendly
• No asphalt fumes or unpleasant odor during application
–
–
–
–
–
Ease of Application
Less Mess
Speed
Good for Poor Access Jobs
Color Complement Ability
• With steep slope roof
• Systems Can Be Used Over Many
Types of Decks
– Nailable (wood, etc.)
– Non-nailable (concrete, steel decks, etc.)
– Over Insulation
Technical Developments in SelfAdhering Roofing Systems
• Self-Adhering Roofing Systems Characteristics
– No Torch or Hot Asphalt Needed
• Improved Safety
• Reduced Insurance Exposure
– Cleanliness
– Minimal Tools and Equipment Needed
– Durability
EPDM Roofing Association
Self-Adhering
Roofing Systems Overview
• Low Slope Self-Adhering Roofing Systems Requirements
–
–
–
–
–
–
Waterproof
Meet structural load requirements
Resistant to fire and wind uplift
Provide UV deflection
Compatible with insulation where applicable
Provide a suitable surface for necessary routine
foot traffic to access rooftop equipment
• All components of the low slope self-adhering roof
assembly must be compatible with one another
• Necessity for future repair and recovering possibilities in the design
of a roof should be taken into consideration
• Temperature Limitations – 50F+
• Clean, dry, no dust…
Self-Adhering
Roofing Systems Overview
• Components of Low Slope Self-Adhering Roof Systems
– The three basic components of a low slope self-adhering assembly are:
• Roof deck
• Insulation
• Roof membrane
Use of Layered Self-Adhering
Roofing Systems
• 1, 2-Ply and 3-Ply Systems Based on Roof Needs
TPO – 1-Ply System
Cap
MB’s - 2-Ply System
• Comprised of a base sheet and cap sheet
Mid Ply
Base
• For use on small, residential projects
– MB’s - 3-Ply System
• Comprised of base sheet, mid-ply membrane and cap sheet
• For use on large, commercial projects
• Surface Film Adherence
– A surface film on top of the base sheet or mid-ply membrane designed to improve
adherence and durability
Self-Adhering
Roofing Systems Overview
• Installation Guidelines- Low Slope Self-Adhering Roof Systems
– Roof membrane layout always begin at the low point of the roof
– MB’s - Self Adhered Seams
– TPO’s - Heat Welded Seams
– All membrane plies are installed with overlapping side and endlaps.
Sidelaps of the various plies are offset
– MB’s - T-Laps Sealed,
– TPO’s – T-Laps, End Laps Covered.
– While every aspect of the low slope self-adhering roof specification and the quality of the
installation is important, flashing and termination details are critical
Technical Developments in SelfAdhering Roofing Systems
• Self-Adhering MB Roofing Systems Characteristics
– Newest Technology
– Latest in asphalt technology
– Offers substantial waterproofing
– Carriers: fiberglass, polyester mats - stable
– Dedicated primers and mastics to complete installation
– Weathering grade compound top side - adhesive asphalt bottom layer
• Different from 1980’s versions
Three-Layer
Self-Adhering Roofing Systems
• Overview of Self-Adhering Systems Installation
– Application recommended above 45-50°F (10°C)
– Low-side, shingle fashion
– Cleanliness
• Dispose of tear-off film
• Dust
– End lap preparation
• Adhesive
• Hot air gun, Welding, Patching
– Roller (heavyweight) to press into place
– T-Lap Sealing
– End Lap Treatment
Three-Layer
Self-Adhering Roofing Systems
• MB Installation
Details
– Rain Gutter
– 2-Ply Installation
Three-Layer
Self-Adhering Roofing Systems
• Installation
Details
– 3-Ply Installation
Three-Layer
Self-Adhering Roofing Systems
• MB Installation Details (Cont)
– Flashing Specifications
• Two main types:
– Membrane (base flashing)
– Metal (counter-flashing and cap flashing)
Polyglass
Three-Layer
Self-Adhering Roofing Systems
• MB Installation
Details (Cont)
– Perimeter Detail
Three-Layer
Self-Adhering Roofing Systems
• MB Installation
Details
– Shingle Transition
Self-Adhering Roofing
Systems Code Information
• ASTM Standards
– None yet for specific SBS/APP/TPO Self Adhered Low Slope sheets…
– Work in progress to develop standards to address APP and SBS based selfadhesive membranes used in both steep-slope and low-slope applications
– ASTM D1970, “Standard Specification for Self-Adhering Polymer Modified
Bituminous Sheet Materials Used as Steep Roofing Underlayment for Ice Dam
Protection…for now
• International Code Council (ICC) Approvals
– ICC-Evaluation Services – Reviewing…
– Wind Uplift & Fire Ratings
– Available – Check Classification Listings
Course Summary
• We have reviewed the following topics:
– The definition of a low slope roof
– Some of the historical and technical developments in self-adhering roofing
systems
– The components of a self-adhering roofing assembly
– Key technical developments of self-adhering TPO and modified bitumen
roofing systems
– The principle factors that need to be considered in the design of a selfadhering roofing system
– The key considerations needed for the successful installation of a selfadhering roofing system
Thank You for Your
Participation
?
CRCA Education Series
Self-Adhering
Membrane
Roofing Systems
for Low Slope
Roofs