Chapter
25
Post-and-Beam
Construction
Objectives
• List the advantages and disadvantages of postand-beam construction.
• Describe general specifications for supporting
posts.
• Compare transverse and longitudinal beams.
• Describe how roof and floor planks should be
selected and installed.
• Sketch basic construction details of structural
insulated panels (SIPs) and box beams.
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Plank-and-Beam Construction
• Consists of large framing
members— posts,
beams, planks
• Members may be spaced
farther apart than
conventional framing
members
• Often combined with
conventional framing
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Framing Comparison
National Forest Products Assn.
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Advantages
• Distinctive effect of
exposed beams
• Added ceiling height
• Savings in labor
• Simplicity of framing
around door and window
openings
• High resistance to fire
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Limitations
• Installation of electrical
wiring, plumbing, and
heating is more difficult
• Extra framing must be
provided under loadbearing areas
• Extra members may be
needed to provide lateral
stability
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Foundations and Posts
• May consist of continuous
walls or simple piers
located under posts
• Posts must be strong and
large enough to support
loads
• May use bearing blocks
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Spacing for Posts
• Distance between posts
depends on basic design
of structure
• Posts are usually evenly
spaced along length of
building
• Plate is attached to top of
post in single-story
construction
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Floor Beams
• May be solid, gluelaminated, or built-up
• Spacer blocks or box
beams may be used
• Design of sills for plankand-beam floor can be
similar to regular platform
construction
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Beam Descriptions
• Best to use solid timbers
for small beams or rustic
appearance
• Laminated beams are
made in range of sizes
and finishes
• Beams can be covered
for better appearance
when left exposed
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Roof Beams
• Support roof planking or
panels
• Transverse beams are
similar to exposed rafters
on wide spacings
• Longitudinal beams run
parallel to supporting
sidewalls and ridge beam
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Beam Supports
• Beams must be
supported on posts or
stud walls with heavy top
plate
• Transverse beams are
joined to sides of ridge
beam or supported on top
of beam
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Fasteners
• Mortise-and-tenon joints
can be used with wood
pegs as fasteners
• Butt joints and metal
fasteners can also be
used
• Concealed connectors
can be used
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Partitions
• More difficult to construct
under exposed beam
ceiling
• Partitions parallel to
transverse beams have
sloping top plate
• Additional support must
be provided for some
partitions
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Planks
• Can support greater
loads if they continue
over multiple spans
• Materials should have
proper moisture content
levels
• Plank roof structures may
need insulation and vapor
barrier
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Structural Insulated Panels
(SIPs)
• Designed to carry loads
over wide spans
• Can be applied on
outside of frame, leaving
posts and beams
exposed inside
Yankee Barn Homes, Inc.
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SIP Construction
• Rigid foam insulation is
bonded to oriented strand
board (OSB)
• Skins of SIPs can provide
great strength and rigidity
to resist loads imposed
on roof
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Box Beams
• Provide structural unit
that can span distances
up to 120′
• Made of plywood webs
laminated to seasoned
lumber flanges
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Laminated Beams and Arches
• Available in many shapes and sizes
• Laminated wood offers
–
–
–
–
–
Strength
Safety
Economy
Permanence
Flexibility in building design
American Institute of Timber Construction
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Shapes for Laminated Beams
• In residential work,
beams are usually
straight or tapered
• For other buildings,
beams are often formed
into curves, arches, and
other complex shapes
APA–The Engineered Wood Association
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Prefabricating Structures
• Design process involves
customizing homes to
wishes of homeowner
• Timbers are selected
from factory stock
• Production machines are
used to cut mortises and
tenons
Yankee Barn Homes, Inc.
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Wall and Roof Sections
• Fabricated into large
panels on factory floor
• Rigid insulation is
installed in sections
• Windows, exterior siding,
and interior wall
coverings are also
installed
Yankee Barn Homes, Inc.
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Assembly
• Completed panels are
loaded onto trailers and
transported to building
site
• Frame is erected onsite
by builders
• Wall and roof panels are
then installed
Yankee Barn Homes, Inc.
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