1 / 18

Types of Roofs and Cutting Common Rafters

Types of Roofs and Cutting Common Rafters. Dr. David Agnew Arkansas State University. Types of Roofs: In Agricultural Applications. Hip Gothic Combination Uneven span. Types of roofs. Types of Rafters. Parts of A Roof….. . Definition of a Rafter.

sen
Télécharger la présentation

Types of Roofs and Cutting Common Rafters

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. Types of Roofs and Cutting Common Rafters Dr. David Agnew Arkansas State University

  2. Types of Roofs:In Agricultural Applications Hip Gothic Combination Uneven span Types of roofs

  3. Types of Rafters

  4. Parts of A Roof…..

  5. Definition of a Rafter • Single timber supporting a roof section.

  6. Kinds of Rafters

  7. Parts of a Rafter

  8. Rafter Slope • Roofs are not flat • Pros and cons of low or steep roofs • Cost of steep is higher for materials • Harder and more dangerous to work on if steep • Steep roofs have greater ability to withstand load • Pitch • Expressed as a Fraction ¼, 1/6, 1/8, etc. • Rise/foot of run • Example: 2 in./ ft. • Used in more plans today than pitch

  9. Calculating Pitch

  10. Procedures for Rafter Layout • Three Techniques • Stepping method • Figuring length using A2 + B2 = C2 • Rafter Table

  11. Procedures for Rafter Layout • Three Techniques • Stepping method # steps= feet of run Ex 10 12 etc. Step 1 2 3

  12. Procedures for Rafter Layout • Three Techniques • A2 + B2 = C2 2 C 2 B A 2 A= Run of Roof Example: If A=4 , B=3 then what would c=? 16 + 9 = 25 then C= sq root of 25 which is 5

  13. Resources Needed to Layout and Cut a Rafter • Timber/Lumber (2x4, 2x6, 2x8, etc) • Measuring Device-- Tape Measure • Marking Pencil • Rafter/Carpenter’s Square • Saw • Sawhorses • Note: The class project rafter layout will need some different supplies.

  14. Steps to layout of Rafter Using the Rafter Table. • Determine Rise or Pitch • Determine the Span and/or Run • Using the table for common rafters on the Rafter Square Identify the length of rafter per ft of run.

  15. Rafter Layout Continued • Multiply the run times the number from the table. That number is the length of the rafter… But you are not done yet… • Identify the end of the board that you want to make the ridge cut. • The square has a tongue and a body • Tongue is the smaller of the two 18 inches long and 1 ½ inches wide. • Body is larger 24 inches long and 2 inches wide.

  16. Parts of a Framing or Rafter Square 1.5 inches thick Tounge • inches thick 18 " Body 24 "

  17. Proper Use of the Square • Always work from one side of the square (never flip it over). • Remember to either use the numbers from the outer edge or inner edge, but do not use both at one time.

  18. Ridge Cut • Using the appropriate numbers on the square (ex. 4 and 12) place the square near the end of the board where the cut is to be made. See picture below.

More Related