1 / 64

Chapter 13

Chapter 13. Sill and Floor Construction. Chapter 13 Overview. Platform Framing / Balloon Framing Joists and Beams / Floor Trusses Subfloor Cantilevered Joists Engineered Wood Products Post and Beam Construction. (continued). Learning Objectives.

minnie
Télécharger la présentation

Chapter 13

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 13 Sill and Floor Construction 1

  2. Chapter 13 Overview • Platform Framing / Balloon Framing • Joists and Beams / Floor Trusses • Subfloor • Cantilevered Joists • Engineered Wood Products • Post and Beam Construction (continued) 2

  3. 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) 3

  4. Learning Objectives • Explain the principles of post and beam construction. • Select the appropriate engineered wood products for specific applications in residential construction. 4

  5. Introduction • Framing methods vary from one section of the country to another. • Selection factors include, personal preference, climate, geography and local codes • Two basic types of floor framing are: • Platform framing. • Balloon framing. 5

  6. Introduction • Typical floor framing structural components include: • Plates. • Joists. • Studs. 6

  7. 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. 7

  8. Platform Framing • Construction is safer 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 or sill plate. 8

  9. Platform Framing • Box sill construction. 9

  10. Platform Framing • Detail of the first and second floor. • Using box sill construction. 10

  11. Sealing the Sill • A seal is required between the foundation and sill plate. • The seal prevents outside air from entering the house. 11

  12. 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. 12

  13. 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. 13

  14. Balloon Framing Sill Construction • Solid (standard) sill. • Studs are nailed directly to the sill and joists. • No header is used. 14

  15. Balloon Framing for Second Floor • Joists are supported by a ribbon and nailed to the studs on the second floor level. 15

  16. Joists and Beams • Joistsprovide 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". 16

  17. Joists and Beams • Standard lumber sizes. • See p.276 17 (National Forest Products Association)

  18. 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. 18

  19. Procedure for Using Span Data Chart • Select species of wood to be used. • Select appropriate live load. “30” • Determine lumber grade to be used. • Number 2 • Scan the span data chart. • Select the appropriate joist size. 16" OC spacing is typical. 19

  20. Floor Joist Span Data 20

  21. 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". 21

  22. 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. 22

  23. Steel Framing Detail • Typical steel framing where floor joists bear on the foundation. 23

  24. Joists and Beams(Beams) • When the span is too great for unsupported joists, a beamis typically usedto reduce the span. • A beam may be a solid timber, built-up beam, or a metal S- or W-beam. 24

  25. Methods of Supporting Floor Joists with Beams 25

  26. Openings in the Floor • Openings in the floor for stairs and chimneys required double joist framing. 26

  27. 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. 27

  28. Metal Bridging 28

  29. 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. 29

  30. Floor Trusses • Trusses provide clear spans with a minimum depth in a lightweight assembly. 30 (Trus Joist)

  31. Engineered Floor Trusses • Usually fabricated from 2" x 4" or 2" x 6" lumber and generally spaced 24" OC. • Each truss has a built-in camber. • Webs may be metal or wood. • A floor truss will often eliminate the need for a beam. 31

  32. Typical Truss Webs 32 (TrusWal Systems, Inc.)

  33. Wood I-Beams or Joists 33 (Boise Cascade Corporation)

  34. 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'. 34

  35. Wood I-Beams or I-Joists • Advantages of wood I-beams: • Speed of construction. • Have knockout holes for plumbing and electrical cable. • Dimensionally stable and very straight. • No cross bridging needed • Disadvantages of wood I-beams: • Require more effort to cut. • More expensive than lumber or trusses. 35

  36. Wood I-Beams or Joists • Installation of wood I-beams are similar to traditional floor joists or rafters. • Should not be mixed with solid lumber in the same assembly. • Use the size chart on p. 799 • “Trus Joist Recommended Spans” 36

  37. Wood I-Beams or Joists 37 (Boise Cascade Corporation)

  38. Cantilevered Joists • Cantilevered joists are required when a section of the floor projects beyond the foundation (or level below). • Generally, joists should extend inside the structure twice the distance they overhang 38

  39. Subfloor • The subflooris 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. 39

  40. Typical Panel Products 40 (Georgia-Pacific Corporation)

  41. Installing Subfloor Panels • Joist spacing must be very accurate. • All panel edges must be supported. 41

  42. Installing Subfloor Panels • Plywood grain direction of the outer plies should be at right angles to joists. • To reduce squeking • Panels may be glued as well as nailed or screwed • Use tongue & groove panels. 42

  43. Engineered Wood Products • Engineered wood products (EWPs) combine wood veneers and fibers with adhesives to form beams, headers, joists, and panels. • They increase the supply of usable wood from smaller and inferior trees. 43

  44. Engineered Wood Products • The use of engineered wood products will continue to grow. • Advances in adhesive technology have made EWPs possible. 44

  45. 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. 45 (Alpine Structures)

  46. 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. 46

  47. Engineered Wood Products • Application of EWPs. 47

  48. 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. • Outer layers are oriented to the long dimension, others are perpendicular. 48

  49. Oriented Strand Board 49 The Engineered Wood Association)

  50. 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. 50

More Related