Roof & Ceiling Structures Flashcards
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Questions and Answers

What is the minimum clearance from insulation for recessed electrical fixtures not rated for contact with insulation?

3"

What are the implications of insulation that is only 2" thick, wet, compressed, interrupted by gaps or voids, or missing?

Heat loss, damage to finishes, localized heat loss, ice damming, reduced R-value.

All of the following could indicate spreading rafters EXCEPT

  • Sagging rafters
  • Uneven roof line
  • Cracks in interior ceilings running perpendicular to the outside walls (correct)
  • Visible gaps between rafters

    • Define rafters.

    <p>Sloped structural members on steep roofs that support sheathing.</p> Signup and view all the answers

    Which of the following statements applies to notching or putting holes in truss members?

    <p>Neither holes nor notches are permitted anywhere on a truss</p> Signup and view all the answers

    Which of the following are truss conditions that should be reported?

    <p>Hole at the 1/4 point of web, weak gusset connection, truss uplift.</p> Signup and view all the answers

    What is a gusset plate used for in a roof structure?

    <p>To connect members of a truss together.</p> Signup and view all the answers

    Define ceiling joists.

    <p>Horizontal members that support insulation and ceilings.</p> Signup and view all the answers

    What is the minimum recommended end bearing for rafters and ceiling joists?

    <p>1 1/2 inches on wood and 3 inches on masonry.</p> Signup and view all the answers

    All of these are common joist problems EXCEPT

    <p>Joists running parallel to walls below</p> Signup and view all the answers

    What are 4 common joist problems you will see on inspections?

    <p>Rot and insect damage, inappropriate notching or holes, sagging joists, poor end bearing.</p> Signup and view all the answers

    What are 3 common subfloor materials?

    <p>Planking, plywood, waferboard.</p> Signup and view all the answers

    Subfloors act like:

    <p>Joists and beams.</p> Signup and view all the answers

    At the top and bottom edges of sheathing, support may be provided by ___ clips.

    <p>H clips</p> Signup and view all the answers

    Rafter ties must be spaced no more than:

    <p>4 feet on center.</p> Signup and view all the answers

    Joists see vertical loads only.

    <p>False</p> Signup and view all the answers

    Roughly how far can these common joists span if spaced 16 inches apart? (2x8, 2x10, 2x12)

    <p>2x8 (11 1/2 feet), 2x10 (14 feet), 2x12 (16 feet).</p> Signup and view all the answers

    The function of joists is to:

    <p>Transfer live loads to beams.</p> Signup and view all the answers

    What is the main function of intermediate support/collar tie?

    <p>Help prevent rafter sag.</p> Signup and view all the answers

    What is the difference between a knee wall and a purlin?

    <p>Knee walls provide support for rafters by transferring loads down, while purlins act as beams running under rafters.</p> Signup and view all the answers

    Knee walls are also called dwarf walls, struts, or strongbacks.

    <p>True</p> Signup and view all the answers

    Purlins are typically 2x4 or 2x6.

    <p>True</p> Signup and view all the answers

    The purlin should be the same size as the ridge.

    <p>False</p> Signup and view all the answers

    An inspector can think of purlins as small beams that run under the midpoint of all rafters.

    <p>True</p> Signup and view all the answers

    Does a roof truss support long ceiling spans?

    <p>False</p> Signup and view all the answers

    What is the purpose of a roof truss system?

    <p>A triangular structure used to support a roof.</p> Signup and view all the answers

    Which is a member of a truss system?

    <p>Web.</p> Signup and view all the answers

    Name 2 engineered wood products that may replace conventional joists.

    <p>Trusses, Wood I-joists.</p> Signup and view all the answers

    How does a ledger board support joists?

    <p>The ledger board is fastened to the beam near the bottom, and the joist rests on the top of the ledger board.</p> Signup and view all the answers

    Common attic access hatch problems include all of the following EXCEPT

    <p>Over-sized</p> Signup and view all the answers

    How might you tell the difference between roof sheathing sag and rafter sag from the exterior of the house?

    <p>Sheathing sag is a repetitive pattern across the roof, while sagging rafters cause a dishing in the entire roof surface.</p> Signup and view all the answers

    Study Notes

    Roof & Ceiling Structures Overview

    • Minimum clearance for recessed electrical fixtures not rated for insulation contact is 3 inches.
    • Insulation issues:
      • 2 inches thick leads to heat loss.
      • Wet insulation can damage finishes and perform poorly.
      • Gaps or voids cause localized heat loss and ice damming.
      • Compressed insulation reduces R-value.
      • Missing insulation increases heat loss and ice damming risk.

    Structural Members

    • Rafters: Sloped structural components from roof peak to eaves, varying from 2x4 to 2x10 inches and spaced 12 to 24 inches apart.
    • Notching or drilling holes in truss members is prohibited.
    • Indicators of truss issues include holes at the 1/4 point of web, weak gusset connections, and truss uplift.
    • Gusset plates are used to connect truss members.

    Joists and End Bearing

    • Ceiling joists: Horizontal members supporting insulation and ceilings, connecting the bottom ends of opposing rafters, crucial for roof stability.
    • Minimum recommended end bearing: 1.5 inches for wood and 3 inches for masonry.
    • Common joist problems: Rot, insect damage, inappropriate notching, sagging, and poor end bearing.
    • Subfloor materials include planking, plywood, and waferboard; they act like joists and beams.

    Load Management

    • Rafter ties must be spaced no more than 4 feet apart.
    • Joists do not only see vertical loads; they deal with both vertical and lateral pressures.
    • Common joist spans:
      • 2x8 can span approximately 11.5 feet,
      • 2x10 can span around 14 feet,
      • 2x12 can span about 16 feet.

    Support Structures

    • Intermediate supports or collar ties prevent rafter sag.
    • The difference between knee walls and purlins:
      • Knee walls transfer loads to ceilings or walls,
      • Purlins run beneath rafters acting as beams.
    • Knee walls also known as dwarf walls, struts, or strongbacks.

    Truss Systems

    • Purlins are typically 2x4 or 2x6 and serve as support beams.
    • Purlin size does not need to match the ridge size.
    • Roof trusses effectively support long ceiling spans and are triangular structures designed for roof support.
    • Web is a critical member of a truss system.
    • Engineered wood products like trusses and Wood I-joists can replace conventional joists.

    Additional Considerations

    • Ledger boards support joists by being fastened to beams and providing a resting point for the joists.
    • Common attic hatch problems do not include oversized issues.
    • Differentiating roof sheathing sag from rafter sag:
      • Sheathing sag shows repetitive patterns, while rafter sag results in a dishing effect across the roof or a sagging ridge.

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    Test your knowledge on roofing and ceiling structures with these flashcards. Learn about clearance requirements for electrical fixtures and the implications of different insulation conditions. Perfect for students and professionals alike!

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