Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois

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PowerPoint Presentation
PublisherThe Goodheart-Willcox Co., Inc.Tinley
Park, Illinois
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Chapter 13

• Sill and Floor Construction

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Chapter 13 Overview

• Introduction
• Platform Framing
• Balloon Framing
• Joists and Beams
• Floor Trusses
• Subfloor
• Cantilevered Joists

(continued)
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Chapter 13 Overview

• Framing Under Slate or Tile
• Engineered Wood Products
• Post and Beam Construction

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Learning Objectives

• Explain the difference between platform and
  balloon framing.
• Plan the appropriate floor support using joists
  or trusses for a structure.
• Determine proper joist sizes using a typical span
  data chart.
• Describe the components of a floor system.

(continued)
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Learning Objectives

• Explain the principles of post and beam
  construction.
• Select the appropriate engineered wood products
  for specific applications in residential
  construction.

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Introduction

• Framing methods vary from one section of the
  country to another.
• Personal preference and experience are also
  factors.
• Two basic types of floor framing are
• Platform framing.
• Balloon framing.

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Introduction

• Typical floor framing structural components
  include
• Plates.
• Joists.
• Studs.
• Post and beam construction is also used for walls
  and floors.

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Platform Framing

• In platform framing, floor joists form a platform
  on which the walls rest.
• Another platform rests on top of the walls when
  there is a second story.
• Platform framing is used more extensively than
  balloon framing.
• The platform automatically provides a fire-stop
  between floors.

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Platform Framing

• Construction is safe because work is performed on
  a solid surface.
• The sill is the starting point in constructing a
  floor.
• Rests on the foundation and supports the floor
  joists or the studs.
• Generally 2" x 6" lumber.
• Box sill construction is generally used, which
  consists of a 2" x 6" plate called a mudsill.

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Platform Framing

• Box sill construction.

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Platform Framing

• Detail of the first and second floor.
• Using box sill construction.

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Sealing the Sill

• A seal is required between the foundation and
  sill plate.
• The seal prevents outside air from entering the
  house.

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Balloon Framing

• Balloon framing has diminished in importance in
  recent years.
• Distinguishing features include
• Wall studs rest directly on the sill plate.
• Each floor hangs from the studs.
• Two advantages of balloon framing are
• Small potential shrinkage.
• Good vertical stability.

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Balloon Framing

• Disadvantages of balloon framing are
• Less than desirable surface on which to work
  during construction.
• The need to add fire-stops.
• Two types of sill construction are used
• Solid (standard).
• T-sill.

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Balloon Framing Sill Construction

• Solid (standard) sill.
• Studs are nailed directly to the sill and joists.
• No header is used.

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Balloon Framing Sill Construction

• T-sill construction.
• Header rests on the sill and serves as a
  fire-stop.
• Studs rests on the sill and are nailed to the
  header as well as the 8" or 10" wide sill plate.

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Balloon Framing for Second Floor

• Joists are supported by a ribbon and nailed to
  the studs on the second floor level.

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Joists and Beams

• Joists provide support for the floor.
• Usually made from a common softwood.
• Southern yellow pine, fir, larch, hemlock, or
  spruce.
• Engineered wood and metal joists are also
  available.
• Floor joists range in size from 2" x 6" to 2" x
  12".

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Joists and Beams

• Standard lumber sizes.

(National Forest Products Association)
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Joists and Beams(Joists)

• Size of joist required depends on the span, load,
  species and grade of wood, and joist spacing.
• When using metal joists, the gauge of metal
  should be considered instead of species and grade
  of lumber.
• Floor joists may be spaced 12", 16", or 24" on
  center.

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Procedure for Using Span Data Chart

• Select species of wood to be used.
• Select appropriate live load.
• Determine lumber grade to be used.
• Scan the lumber grade row and note the maximum
  spans.
• Select the joist size and spacing that will
  support the desired live load 16" OC spacing is
  typical.

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Floor Joist Span Data
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Floor Joist Span Data
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Floor Joist Span Data
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Span Data Example

• Span is 14'-0" and number one dense southern pine
  is to be used.
• Live load is 30 pounds per square foot.
• Chart shows the following choices.
• 2" x 8" joists 12" OC or 16" OC.
• 2" x 10" joists 12" OC, 16" OC, or 24" OC.
• 2" x 12" joists 12" OC, 16" OC, or 24" OC.
• Best selection is 2" x 8" joists, 16" OC. This
  will span up to 14'-5".

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Steel Floor Joists

• Steel floor joists are beginning to be accepted
  for residential construction.
• Joist depths ranging from 6" to 12" with
  thicknesses from 0.034" to 0.101" are generally
  used.
• Usual spacing is 24" OC, but other spacing is
  also used.

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Steel Framing Detail

• Typical steel framing where floor joists bear on
  the foundation.

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Joists and Beams(Beams)

• When the span is too great for unsupported
  joists, a beam or load-bearing wall is needed to
  reduce the span.
• A beam may be a solid timber, built-up beam, or a
  metal S- or W-beam.
• Load-bearing walls may be concrete block, cast
  concrete, or frame construction.

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Methods of Supporting Floor Joists with Beams
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Supporting Partition Walls

• Partition walls that run parallel to the floor
  joists require added support.

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Openings in the Floor

• Openings in the floor for stairs and chimneys
  required double joist framing.

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Cross Bridging

• Cross bridging is used to stiffen the floor and
  spread the load over a broader area.
• Bridging boards or metal bridging are used.

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Metal Bridging
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Floor Trusses

• A truss is a rigid framework designed to support
  a load over a span.
• Floor trusses are often used in place of floor
  joists in residential construction.
• Floor trusses consist of a top chord, bottom
  chord, and web.
• Chords are the horizontal flanges on the top and
  bottom of the truss.
• The web is the truss framework.

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Floor Trusses

• Trusses provide clear spans with a minimum depth
  in a lightweight assembly.

(Trus Joist)
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Engineered Floor Trusses

• Engineered floor trusses are designed with the
  aid of computers.
• Usually fabricated from 2" x 4" or 2" x 6" lumber
  and generally spaced 24" OC.
• Each truss has a built-in camber.
• Stress-graded lumber is used in their
  construction to reduce material.
• Webs may be metal or wood.

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Typical Truss Webs
(TrusWal Systems, Inc.)
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Subfloor

• The subfloor is attached to the top of the floor
  joists and provides a work surface during
  construction.
• Plywood, tongue-and-groove boards, common boards,
  and other panel products are used for subfloors.
• Panel products reduce installation time.
• 5/8" or 1/2" thick plywood is preferred.

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Typical Panel Products
(Georgia-Pacific Corporation)
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Installing Subfloor Panels

• Joist spacing must be very accurate.
• All panel edges must be supported.

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Installing Subfloor Panels

• Plywood grain direction of the outer plies should
  be at right angles to joists.
• Panel products should be staggered so that end
  joints of adjacent panels are on different
  joists.
• Panels may be glued as well as nailed to the
  joists to increase strength and reduce squeaking
  and nail pops.

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Cantilevered Joists

• Cantilevered joists are required when a section
  of the floor projects beyond a lower level.
• When floor joists run perpendicular to the
  cantilevered section, longer joists form the
  cantilever.
• When joists are parallel to the overhanging area,
  cantilevered joists are required.

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Cantilevered Joists

• Generally, joists should extend inside the
  structure twice the distance they overhang.

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Framing Under Slate or Tile

• Flooring materials such as ceramic tile, slate,
  or stone floors require a substantial base.
• If a concrete base is provided, the floor framing
  must be lowered to provide for the concrete.
• Dead weight may be as much as 50 pounds per
  square foot.

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Framing Under Slate or Tile

• A smaller size joist may be used and the space
  between joists reduced to provide adequate
  support.
• Cement mortar mix is generally used for the base.

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Engineered Wood Products

• Engineered wood products (EWPs) combine wood
  veneers and fibers with adhesives to form beams,
  headers, joists, and panels.
• EWPs have uniformly high quality and strength.
• They increase the supply of usable wood from
  smaller and inferior trees.

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Engineered Wood Products

• The use of engineered wood products will continue
  to grow.
• Advances in adhesive technology have made EWPs
  possible.
• Phenol-formaldehyde and urea-formaldehyde are the
  most common types.
• Phenolics are more expensive than urea resins.

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Engineered Wood Products

• Band boards are available in 9-1/4",11-1/4",
  12", 14", and 16" depths.
• Engineered headers are available in 1-1/4" depth
  and 3-1/2" width.

(Alpine Structures)
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Engineered Wood Products

• Advantages of EWPs
• High quality and consistency.
• No knots, checks, or warps.
• Uniformly dried to 8 to 12 moisture content.
• Provides superior design flexibility.
• Disadvantage of EWPs
• Lack of industry standards.

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Engineered Wood Products

• Application of EWPs.

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Oriented Strand Board

• Oriented strand board (OSB) is made from long
  strands of wood and resin.
• First introduced in 1978 as a low-quality
  particle board panel.
• Aspen is the preferred wood for making OSB.
• Outer layers are oriented to the long dimension,
  others are perpendicular.

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Oriented Strand Board
The Engineered Wood Association)
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Oriented Strand Board

• Advantages of OSB
• Less expensive than plywood.
• Unique appearance can be appealing as a design
  element.
• Disadvantages of OSB
• Subject to swelling.
• Not designed for exposure to the elements.

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Oriented Strand Board

• OSB is made in panel sizes similar to plywood,
  typically 4' x 8'.
• Available in sizes up to 8' x 24'.
• Allow 1/8" space along edges to prevent buckling
  problems.
• Use the same nailing schedules that apply to
  plywood.

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Parallel Strand Lumber

• Parallel strand lumber (PSL) is made from thin
  strands of wood.
• Fairly new category of EWP.
• Used for beams, columns, and headers.
• High strength and span capacity.
• Low-moisture content eliminates shrinking and
  checking.
• Large billets 12" wide by 17" deep are formed and
  then sawn to specific sizes.

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Parallel Strand Lumber
(Alpine Structures)
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Parallel Strand Lumber

• Advantages of PSL
• Very strong.
• Allows long spans and more design flexibility.
• Disadvantages of PSL
• Engineered connections are required for
  side-loading joists on one side.
• Should not be drilled or notched.
• Storage conditions should prevent swelling.

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Parallel Strand Lumber

• Widths available from 1-3/4" to 7".
• Two plies of 2-11/16" members will match a
  typical 5-1/2" wall.
• Lengths up to 66' available.
• Eliminates the need for built-up beams.

(Alpine Structures)
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Laminated Veneer Lumber

• Laminated veneer lumber (LVL) is made from
  veneers stacked parallel to each other.
• LVL is used for headers, beams, joists, columns,
  and flanges for wood I-beams.
• Similar to plywood, but all plies are parallel to
  provide maximum strength.
• Southern yellow pine and Douglas fir are
  generally the woods of choice.

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Laminated Veneer Lumber

• LVL is produced in a continuous billet up to
  1-3/4" thick and 4' wide and two or more billets
  can be glued together to form thicker pieces.

(Trus Joist)
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Laminated Veneer Lumber

• Advantages of LVL
• High strength allows long spans.
• Can be built-up on site to form larger members.
• Disadvantages of LVL
• More expensive than solid lumber.
• Lower moisture content than solid lumber.
• Must be sized for specific load conditions.

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Laminated Veneer Lumber

• The 1-3/4" thick billet is most common.
• Can be used individually for joists or combined
  to form headers or beams.
• Available in depths from 5-1/2" to 14" and
  lengths up to 66'.
• LVL generally should not be mixed with solid
  lumber in the same floor assembly.
• LVL beams should not be drilled .

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Glue-Laminated Lumber

• Glue-laminated members (glulam beams) consist of
  1x or 2x lumber glued into desired shapes.
• Glue-laminated beams, columns, and arches were
  the first engineered wood products.
• Virtually any length or depth can be produced.

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Glue-Laminated Lumber

• This construction makes extensive use of
  glue-laminated beams.

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Glue-Laminated Lumber

• Glue-laminated beams are accepted by all three US
  model building codes.
• Three appearance grades are available.
• Industrial grade The least attractive containing
  visible glue stains, press marks, and knot holes.
• Architectural grade Sanded on four sides with
  knot holes filled with putty.
• Premium grade All checks and holes filled.

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Glue-Laminated Lumber

• Advantages of glulams
• High strength.
• Available either straight or cambered.
• Dimensionally stable and attractive.
• Disadvantages of glulams
• Cost is high.
• Requires special handling and storage.
• Requires special equipment to handle.

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Glue-Laminated Lumber

• Installation
• Technical support is generally required.
• Producers provide span charts, installation
  details, technical assistance.
• Special connectors are required for these large
  members and heavy loads.
• Special handling is required to reduce checking
  and preserve the finish.

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Wood I-Beams or Joists

• Wood I-beams or joists are generally made from 2"
  x 4" machined-stressed lumber or LVL.
• Webs are usually made from 3/8" OSB.
• They are available in flange widths of1-3/4" and
  2-5/16" and depths from9-1/2" to 20" and lengths
  up to 66'.
• Presently, each manufacturer uses their own
  proprietary process.

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Wood I-Beams or Joists
(Boise Cascade Corporation)
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Wood I-Beams or Joists

• Advantages of wood I-beams
• Speed of construction.
• Have knockout holes for plumbing and electrical
  cable.
• Dimensionally stable and very straight.
• Disadvantages of wood I-beams
• Require more effort to cut.
• Not universally accepted.
• More expensive than lumber or trusses.

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Wood I-Beams or Joists

• Installation of wood I-beams are similar to
  traditional floor joists or rafters.
• Typical nails, tools, and metal connectors can be
  used.
• Should not be mixed with solid lumber in the same
  assembly.
• Web stiffeners or blocks are normally used at
  bearing points.

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Wood I-Beams or Joists

• Several types of engineered lumber are used in
  this dwelling.

(Boise Cascade Corporation)
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Post and Beam Construction

• Post and beam construction provides greater
  freedom of design.
• The system uses larger structural sizes, framing
  connectors, and unique joining methods.
• Posts carry most of the weight
• The walls are usually curtain walls.
• Curtain walls provide for wide expanses of glass
  without the need for headers.

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Post and Beam Construction
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Post and Beam Construction
(The Engineered Wood Association)
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Post and Beam Construction

• Curtain wall example.

(Pozzi Wood Windows)
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Post and Beam Construction

• Foundation for a post and beam structure may be
  continuous or isolated footings on which each
  post is located.
• Posts should be at least 4" x 4" or 6" x 6" if
  they support the floor.
• Beams should be solid, laminated, reinforced with
  steel, or plywood box beams.

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Post and Beam Construction

• A variety of beams used in post and beam
  construction.

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Post and Beam Construction

• The spacing and span of the beams will be
  determined by the size and type of materials and
  the load to be supported.
• Generally, a span of 7'-0" may be used when 2"
  thick tongue-and-groove decking is applied.
• Thicker beams should be used if the span exceeds
  7'-0".
• Span tables are provided in the text.

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Post and Beam Construction

• There are two systems of roof beam placement
• Longitudinal method Beams are placed at right
  angles to the roof slope roof decking is laid
  from the ridge to the eaves.
• Transverse method Beams follow the roof slope
  decking runs parallel to the roof ridge.

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Post and Beam Construction

• The longitudinal method.

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Post and Beam Construction

• The transverse method.

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Post and Beam Construction

• Metal connectors.

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Post and Beam Construction

• Installation
• Nailing does not provide a satisfactory
  connection in post and beam construction lag
  bolts are used.
• Metal plates or connectors are used to attach
  post and beam segments.
• Decking planks range in thickness from 2" to 4"
  and are usually tongue-and-grooved along the long
  edges.

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Post and Beam Construction

• Several plank designs used in post and beam
  construction.

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Glossary

• Balloon Framing.
• A method of framing in which the wall studs
  rest directly on the sill plate and each floor
  hangs from the studs.
• Beam.
• A structural member that supports the joists
  and effectively reduces the span.
• Box Sill.
• Consists of a 2" x 6" plate called a sill or
  mudsill and a header that is the same size as the
  floor joist.

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Glossary

• Cantilevered Joists.
• Required when the floor joists are parallel
  to the overhanging (cantilevered) area run
  perpendicular to the floor joists.
• Cement mortar mix.
• A mixture of one part Portland cement and 6
  parts sand.
• Chords.
• The horizontal flanges at the top and bottom
  of the trusses.

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Glossary

• Cross Bridging.
• Used to stiffen the floor and spread the load
  over a broader area.
• Curtain Walls.
• The walls of a post and beam building do not
  support much weight.
• Engineered Wood Products (EWPs).
• Wood veneers and fibers are combined with
  adhesives to form beams, headers, joists, and
  panels that have uniformly high quality and
  strength.

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Glossary

• Floor Trusses.
• Consist of a top chord, bottom chord, and
  web often used in place of floor joists in
  residential structures.
• Glulam Beams.
• Glue-laminated members that consist of 1x or
  2x lumber glued in stacks to the desired shape
  and size.
• Joists.
• Provides support for the floor or ceiling.
• Laminated Veneer Lumber (LVL).
• An engineered wood product in which veneers
  of wood are stacked in parallel and glued under
  pressure.

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Glossary

• Longitudinal Method.
• A method of post and beam construction where
  beams are placed at right angles to the roof
  slope and the roof decking is laid from the ridge
  pole to the eaves line.
• Mudsill.
• The sill in box sill construction.
• Oriented Strand Board (OSB).
• An engineered wood product in which long
  strands of wood are mixed with resin, placed in
  layers, and pressed and cured.

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Glossary

• Parallel Strand Lumber (PSL).
• An engineered wood product in which thin
  strands of wood are glued together under
  pressure.
• Platform Framing.
• A method of framing where the floor joists
  form a platform on which the walls rest.
• Post and Beam Construction.
• Uses posts, beams, and planks as framing
  members that are larger and spaced farther apart
  than conventional framing members.

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Glossary

• Sill.
• The lowest member of the frame of a
  structure, it rests on the foundation and
  supports the floor joists or the uprights (studs)
  of the wall.
• Subfloor.
• Affixed to the floor joists provides the
  surface on which the underlayment for the final
  finished floor will rest.
• Transverse Method.
• A method of post and beam construction where
  the beams follow the roof slope and the roof
  decking runs parallel to the roof ridge.

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Glossary

• Web.
• The framework between the chords.
• Wood I-Beams.
• Typically made from 2" x 4" machine-stressed
  lumber or LVL flanges grooved to receive a 3/8"
  OSB or plywood web that is glued in place.