Activity 10.2 – Technology – Objectives & Tools          Michael Nauth EDDL5101

Bloom’s Digital Taxonomy and Framing the Gable Roof

Upon completion of this unit you will be able to:-

  • Identify and name the various types of roof designs and roof framing components
  • Draw, layout, calculate, cut, and frame roof components for a Gable rafter roof


  • Follow the links below list the various roof types
  • Highlight the key roof names and roof framing components in your e-text

Roof types – links  Slides 1 – 21, 22 – 26, Note #27 is incorrect.  Why?  Slides #1- 10  Slides #7 – 27, Note # 28 & 29 are incorrect. Why?


  • Follow the links to compare roof shapes to the isosceles and the right-angled triangles
  • Draw a unit roof triangle (5/12) on graph paper lines (run or horizontal side of 12, rise or vertical side of 5), draw squares on each of the 3 sides, and then cut out each square and determine the relationship of the big square to the two smaller ones
  • Repeat for 7 & 12 and use the architectural scale to determine the length of the hypotenuse
  • Compare your measurement to the one found using the Pythagorean theorem

Right-Angled Triangles and Pythagoras’ Theorem


  • Follow the slideshow below to confirm your knowledge of similar triangles
  • Apply the Pythagorean Theorem to find the hypotenuse of the total roof triangle
  • Use the ratio principle of similar triangles to determine the sloped length of the roof
  • Use scaled drawings, the protractor, and the speed square to determine roof rafter angles



  • Find the rafter tables on the framing square
  • Compare the findings on the Framing Square Tables to the calculations using Pythagoras
  • Parallel your findings to the full-sized roof using the HTML below



  • Review the slides on trig ratios à
  • For roof triangles, we use the Tangent ratio (#17 – 20)
  • Right-angled triangles (90E),     Tangent ” =   = O/A=      Rise/Run
  • Apply trigonometric ratio of tangent (rise/run) to calculate roof rafter angles (7/12 slope)
  • Download the Rafter Calculator, experiment with the input values, and check your answer  Rafter Calc.

Rafter Calc

 Creating (digital)

  • Download the program, Google Sketchup,
  • Follow the YouTube videos below to get familiar with the program
  • Draw a building with a Gable roof, using Google Sketchup
  • Determine roof rafter lengths and angles  Getting Started  Layers  Protractor – Roof slope


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