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POST-FRAME BUILDINGS: A LIGHT-COMMERCIAL
MAINSTAY
Copyright © 2011 National Frame Building Association
CONTINUING EDUCATIONThe National Frame Building Association is a Registered Provider with The American Institute of Architects Continuing Education Systems.
This program is registered with the 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.
“With so many structural framing options, building functions, and architectural finishes, post-frame building systems are limited only by the architect’s imagination and creativity.”—Harvey Manbeck, PE PhD, professor emeritus at Penn State University and NFBA technical advisor
Photo courtesy of Kistler Buildings Photo courtesy of Wick
“Post-frame contributes very well to both the environment and the value for your dollar.”
—Cheryl Ciecko, ALA AIA LEED AP CSI GGP, technical director, WoodWorks, a nonprofit initiative of the Wood Products Council
Photo courtesy of Lester Building Systems, LLC Photo courtesy of Fingerlakes Construction Company
• Versatility and range of applications
• Structural features that make these systems unique
• Key performance characteristics • Resources for designing post-frame building
systems
LEARNING OBJECTIVES
Photo courtesy of Morton Buildings
Many architects and design professionals are unfamiliar with post frame.• It is not commonly included in traditional architectural
school curricula.• They incorrectly equate post-frame construction with
post-and-beam construction• They think post frame is only for agricultural buildings
(i.e., barns, storage facilities, or horse facilities).
WHAT IS POST FRAME?
CONVENIENCE STORES
Photo courtesy of Lester Building Systems, LLC
Photo courtesy of Fbi BuildingsPhoto courtesy of Wick Building
COMMERCIAL OFFICE AND VETERINARY CLINICS
Photo courtesy of Morton Buildings
Photo courtesy of Morton Buildings
PUBLIC BUILDINGS
Photo courtesy of Morton Buildings
Photo courtesy of Lester Building Systems, LLC and SL Construction
COMMUNITY BUILDINGS
Photo courtesy of Little Construction Co., Inc.
Photo courtesy of Kistler Buildings
RECEPTION HALLS
Photo courtesy of Lester Building Systems, LLC and Eastern Iowa Building, Inc.
Photo courtesy of Lester Building Systems, LLC and Eastern Iowa Building, Inc.
POST-AND-BEAM CONSTRUCTION
Continuous Footeror Pier Foundation
PostPinned Connection
Girder (Beam)
Floor
Concrete Pier
THIS IS POST FRAME
Figure 1. Post-frame building with trusses supported by embedded posts
Primary frames
Wood ColumnClear span truss
Embedded Post Foundation
Truss-to-Post Connection
THIS IS POST FRAME
Figure 2. Post-frame building mounted on a concrete stem wall
Roof Purlin
Wall Girt
KEY FEATURES OF POST FRAME
Eave Height Post Height
Clear Span
X-section
Post Footing
Post Foundation
Sidewall Post
TrussPurlins
Girts
Splashboard
• wood sidewall columns • wide bay spacing—8 ft and greater• large clear spans—over 100 ft • embedded wood columns or concrete piers• attached wall and roof sheathing or cladding
form structural shearwall/structural diaphragm system for resisting lateral loads
KEY FEATURES OF POST FRAME
• Solid-sawn, glued-laminated, or mechanically (nail) laminated wood
• Nominal 6x6, 6x8, 8x8, or 8x10 cross section• Typically spaced 4, 6, 8, 12, or 16 ft on center
along sidewall• Any portion of the wood post embedded directly
into the ground and 6–12 in. above grade is pressure preservative treated to AWPA-recommended levels for ground contact
WOOD SIDEWALL COLUMNS
Spliced glued-laminated column• 3- or 4-ply, fabricated
with 2x lumber• lower portion is
preservative treated• upper portion is
untreated
WOOD SIDEWALL COLUMN
WOOD SIDEWALL COLUMNS
Nail-laminated posts with treated bottom spliced to untreated top
Preservative-treated splash board
PRESSURE PRESERVATIVE TREATMENTS
• Posts embedded in the ground, specify:
• use category UC4B or better per AWPA-U1-09
• e.g., [email protected] pcf
PRECAST OR CAST-IN-PLACE REINFORCED CONCRETE PIER
• Pre-cast reinforced concrete pier with post attached above grade
• Entire assembly pre-engineered
• Assembly usually fabricated in factory and shipped to site as a single unit
CAST-IN-PLACE CONCRETE FOUNDATION WALL
Untreated Post
Connection Hardware
Cast-in-Place Concrete Foundation Wall
• Blow-molded plastic or HDPE plastic protective barriers
• Provide moisture and insect protection
• “Enhance protection of copper-based chemical treated wood posts or laminated columns”
PROTECTIVE POST COVERS
• Pre-engineered metal plate connected 2x lumber trusses typically spaced 4–8 ft on center
• Heavier timber trusses for larger post and truss spacings and aesthetic requirements
• Solid-sawn wood rafters spaced 2–4 ft on center for shorter clear spans
• Glulam rafters for larger rafter spacings or clear spans
ROOF FRAMING
• Posts are connected directly to the roof framing if post and roof framing spacing are the same
• Posts and roof framing are often connected to header beams if post and roof framing spacing are not the same
POST TO ROOF FRAMING CONNECTIONS
POST TO ROOF FRAMING CONNECTION
Block Height
Block
Connection is usually a pinned connection (not a moment-resisting connection).
SOLID SAWN POSTS
1½”Connection with truss fastened to slide of post and with bear block
Connection with truss bearing on notch in post
Typical post to truss connection details for a solid sawn post application
POST TO ROOF FRAMING CONNECTION
• Schematic of typical connection details
• Truss to header (girder)
• Header (girder) to roof
ROOF PURLIN PLACEMENTPurlins oriented flat or “on edge,” depending on truss and purlin spacing
Purlins placed either on top or inset between truss top chords or inset between roof rafters
• Typically 2x4 to 2x8 solid sawn lumber, spaced 24–32 in. apart
• Oriented “flat” on outside face of wall post for smaller post and girt spacings and loads
• “On edge” between adjacent posts for larger loads or post or girt spacings
WALL GIRTS
SECONDARY FRAMING AND BRACING
• Corner bracing in upper chords of trusses• Diagonal bracing for lower chords of trusses• Lower chord stiffeners for trusses• Cross bracing of selected compression webs• Continuous longitudinal bracing of long
compression webs and chords of trusses
• Guide to Good Practices for Handling, Installing, Restraining & Bracing of Metal-Plate Connected Wood Trusses (WTCA and TPI)
• B1 and B3 summary sheets: handling and bracing trusses
• B10 summary sheet: Post-frame truss installation and bracing
TRUSS BRACING
The most economical combination has• laminated wood sidewall and endwall columns• embedded post or embedded concrete pier
foundations• metal-plate connected 2x wood roof trusses and• 26- to 29-gauge ribbed steel roof and wall
sheathing
UNIQUE FEATURES OF PF
• ANSI/ASAE (ASABE) EP 484 for diaphragm design of metal-clad, post-frame rectangular buildings
• ANSI/ASAE (ASABE) EP 486 for shallow post foundation design
• ANSI/ASAE (ASABE) EP 559 for design requirements and bending properties for mechanically laminated columns
PF TECHNICAL RESOURCES
• Structural design proceduresfor PF building systems– PF designer’s primary
reference– www.NFBA.org
PF BUILDING DESIGN MANUAL
• Cost-effective• Energy efficient• Code compliance• Sustainability and greenness• Design flexibility • Durability and strength
BENEFITS OF POST FRAME
• National Frame Building Association (NFBA)
• www.PostFrameAdvantage.com • www.NFBA.org• NFBA
8735 W Higgins Road Suite 300
Chicago, IL 60631
MORE ABOUT POST FRAME
• National Frame Building Association (NFBA)
• www.NFBA.org• www.PostFrameAdvantage.com • NFBA
8735 W Higgins Road Suite 300
Chicago, IL 60631
QUESTIONS AND COMMENTS?