dalton panelized roofs
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roofTRANSCRIPT
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All-Wood and Hybrid Panelized Roof
Structure Systems
Cost Effective Roof Solutions
• “The Wood Products Council” is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.
This program is registered with AIA/CES for continuing professional education. As such, it does not include 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 or product.
• Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
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© Wood Products Council
Learning Objectives:
• Gain the ability to decide which panelized roof system best
suits your building’s needs
• Understand the basic structural, fire protection and
construction aspects of designing and constructing a
panelized roof.
• Learn what resources can help a designer design a high load
diaphragm
• Learn what makes a panelized roof system so cost effective
At the end of this program, participants will be able to know:
What is a panelized roof?
�History
�Structural Components
�Construction/Erection methods
Learning Objective #1 What is a Panelized Roof?� Pre-fabricated roof sections
lifted into place
� Safety, cost, speed
� Two common types
� All wood
� Hybrid
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Evolution of Panelized Roof Construction
Over 40 years ago, a small
California company called
Berkeley Plywood, began with a
revolutionary new method for
framing a roof on industrial and
commercial buildings.
Originally called the Berkeley
Panelized System, this method
of framing became the mainstay
for large wood roof structures
throughout the West Coast
Progression From Plywood to
OSB (Oriented Strand Board)Pre-1980s:� Only CDX or S-1, 5-ply plywood was used� “Wafer” board was used in some residential applications
1980s:� American Plywood Association (APA) brought credibility to the
product� New panel performance standards issued� Building codes in US & Canada accept OSB for same uses as
plywood on a thickness-by-thickness basis – “Structural Use Panels”
Conversion to ‘Hybrid’ Panelized Roofs
1990:
� Spotted Owl & other factors drive the cost off ‘all wood’ systems to an all time high.
� The ‘Hybrid’ panelized roof system is introduced by Panelized Structures, Inc. and Vulcraft steel joists.
� In addition to huge cost savings, the use of open-web steel joists & girders resulted in large bay spacing – 60’ purlin spans & 52’ girder spans became typical.
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Since 1991, Many National
Companies Have Preferred
the “Hybrid” Roof Structure
Out West
Defining Panelized System Elements
Subpurlin / Stiffner
Wood Structural Panel Sheathing
Purlin
Pre-framed Panel
Defining Panelized System Elements
Purlin
Pre-framed PanelPurlin
� 2½” Glulam, I-joist, Open-web truss
� Open-web steel joist
� Stiffeners attached with joist hangers
Defining Panelized System Elements
Sub purlin / Stiffener
Pre-framed Panel
Sub purlin / Stiffener� 3x6/2x6 lumber
� Spaced at 24” oc
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Defining Panelized System Elements
� 4x8, 4x10, or 8x8 jumbo panels
� OSB or plywood
APA Sheathing
Pre-framed Panel
APA Sheathing
Jumbo panel
Defining Panelized System Elements
� Simple span glulam (or Cantilevered Glulam)
� Open-web steel joist
� Pre-framed panel spans between girder lines
GirderGirder
Pre-framedpanel
• All Wood Panelized Roof – Sub-purlins and purlins are wood elements
– Girders are solid or engineered wood
– Decking is always wood structural panel
� Glulam Purlin
� I-Joist Purlin� Open Web Wood Truss Purlin
� Cantilevered Span Glulam
� Balanced layup
� 24F-V8/ 24F-1.8E
� Simple Span Glulam
� Unbalanced layup
� 24F-V4/ 24F-1.8E
Girder Spans
• High Strength Composite (HSC) Glulam
– LVL tension laminations
– No finger joints
– 30F – 32F
– ~20% cost premium
Terminology: Hybrid
� Hybrid Panelized Roof� Purlins and girders are steel
� Sub-purlins are often wood
� Decking is always wood structural
panel
� K-Series**
� Short span
� Ex: 20K5 or 20K240/128
� LH-Series**
� Long span
� Ex: 32LH10 or 32LH310/160
� G-Series**
� Girders
**Steel Joist Institute Specifications
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The Panelized Process
Tilt and brace walls Joists arrive with
nailers attached
OSB and all materials are
delivered inside building
Tie-joists are set per OSHA Sub-purlins are ‘hangered’
with ‘F’ hangers
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What are structural advantages of the panelized roof?� Seismic resistance
� Wind resistance
� Fire Protection
� Ease of Design
Learning Objective #2
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Panelized Wood Roofs Provide
Enhanced Structural Performance
� These wood roof diaphragms can resist 1800 plfshear loads as shown in IBC Table 2306.2.1
Seismic Resistance
Seismic Resistance
Braced Frames
� Interior shear resistance
can be provided with
Brace Frames
� 1/2” JUMBO equals value of 5/8” standard 4x8 panels
� Strength axis installed perpendicular to supports resulting in superior bending values
High FM Wind uplift rating
A 135 mph FM rated wind up lift rating has been assign to the panelized wood roof system.
Figure 10 illustrates a panelized roof system that meets the panel attachment requirements for the various FM Windstorm Classifications.
The Panelized Wood Roof System and
Fire - Wind - Insurance
The panelized w ood roof system performs just as well as the conventional “metal deck” system for buildings with use and occupancy classifications B,F,M or S
• The panelized w ood roof system is just as “Fire-Proof” as the metal deck system when ESFR sprinklers are used - From the FM Data sheet 2-2:
• 3.1 Loss History -There are a total of six known fires involving suppression mode sprinkler protection. In all of these incidents, suppression mode protection was successful and no more than four sprinklers operated. In the two incidents for which detailed information was available, the sprinklers involved were not obstructed.
• The Panelized Wood roof system is “FM insurable”
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Heights & Areas of Type V-b
Buildings with Wood Roofs
Allowable Area
IBC Section 507.3 permits the area of a one-story, Group B, F, M or S building to not be
limited when the building is provided with an automatic sprinkler system throughout in
accordance with Section 903.3.1.1 (NFPA 13) and is surrounded and adjoined by public
ways or yards not less than 60 feet in width.
Allowable Heights
Table 503 shows 40’ max for Type V-b bldgs. + 20’ for sprinklers per 504.
504.2 Automatic sprinkler system increase. Where a building
is equipped throughout with an approved automatic sprinkler
system in accordance with Section 903.3.1.1, the value
specified in Table 503 for maximum height is increased by 20
feet (6096 mm) and the maximum number of stories is
increased by one.
One Story Buildings with All-wood or Hybrid Roofs can
have heights up to 60’ and the area is unlimited
No Structural Expansion Joints (DBL Frame Lines)
Are Required
Design Assistance http://www.apawood.org
http://www.woodworks.org
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Learning Objective #3
Other favorable characteristics of the panelized roof?� Durability
� Environmental benefits
� Cost effectiveness:
� Structure cost
� Roofing & insulation,
� Schedule
� Safety
Norwegian Stave Churches
Urnes Stave Church (c. 1150)
Borgund Stave Church (c. 1180)
Built in 12th & 13th centuries …25-30 still remain today
DurabilityBuildings erected in the 50s are still functional today!Still solid and working as designed for over 50 years!
Carbon is Stored
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Comparing CO2 emissions of
different materials
Sawn lumber
products have a
negative net CO2
contribution
Wood industry
often contributes
biomass energy to
the grid
The Wood Roof Structures are
Green• lumber comes from managed forests, where companies are
planting more trees than they are harvesting.
• OSB is produced from faster growing northern species, not old growth coastal, making good use of the forest resource.
• OSB manufacturers have replanted more that 22 million trees.
• Steel open-web trusses are made from recycled steel.
OSB Roof with Factory Applied Radiant Barrier
With White-Faced Batt Insulation
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Value
It makes dollar sense!
Speed of Erection
The fast erection process cuts construction times - a typical 100,000 square foot warehouse roof takes approximately 2-3 weeks to erect
Floor space free of construction prefab debris during erection
process and sub trades can move in quickly
No expansion jointsRoof membrane can be attached directly to sheathing using a thin DensDeck or
similar protective sheet.
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$1.00 - $3.50 per sq.ft. savings can be realized in a hybrid system when compared to a conventional steel joist metal deck system
Long Term Savings:
• Inexpensive options for energy savings
• Faster construction means the building can be leased sooner
Comparative cost savings
$
Safe erection methods
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Learning Objectives #4
Where can the system be used?
�Industrial Bldgs.
�Warehousing
�Manufacturing
�Light Commercial
�Retail
�Sport Facilities
�Specialty
Where are Panelized Roofs used?
Designed by Kramer and Lawson
� Most commonly with
tilt-up concrete or
masonry walls
� Typical for large, low
slope, roof structures
Where are Panelized Roofs used?
Designed by Structural Design Group
Where are Panelized Roofs used?
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Panelized Roofs
Questions?
This concludes The American Institute of Architects
Continuing Education Systems Course
Mark A. Dalton, SESenior Technical Director – Central US
WoodWorks for Non-Residential Construction
Tel: [email protected]
www.woodworks.org