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HIP ROOFS

HIP ROOFS. Created BY Michael Martin July 2004 / revised may 2007. Hip & Valley Roofs. “3 Basic Principles” All ridges must be level & parallel to wall plates All rafters must be placed at 90 ° to wall plates – regardless of the roof shape

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HIP ROOFS

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  1. HIP ROOFS Created BY Michael Martin July 2004/ revised may 2007

  2. Hip & Valley Roofs • “3 Basic Principles” • All ridges must be level & parallel to wall plates • All rafters must be placed at 90° to wall plates – regardless of the roof shape • All hip and valleys must bisect the angle of the corner • Roof members are set out on centre lines • (Page 316 of text)

  3. Components - handout • Wall plate • Ridge • Centering rafter • Crown end • Hip • Common rafters • Creepers • Purlin

  4. Set out – all relates to center lines Centring Rafters Ridge Hip Crown end rafter

  5. New Members – summary to complete in handout • Hip – Inclined member from wall plate at external corner to end of ridge • Crown end rafter – special rafter running from wall plate (center span position) to end of ridge • Creeper rafter – rafter cut in length to join hip

  6. Set out • Ceiling frame also depends on set out of rafters • Set out as opposite • Refer to handout Page 3

  7. The Ridge for a hipped roof • Length = length of the building – width of building + rafter width • See hand out for reference, last page

  8. Pattern Rafters – page 347 • Now include • Common / centering • Crown end rafter • Creeper rafters Centre line to centre line first

  9. Pattern Rafters • Remember • Common / centering – reduce by ½ thickness of ridge • Crown End – reduce by ½ thickness of common rafter / ceiling rafter • Creepers – are calculated on pattern – by determining long point

  10. Determining long point of creeper • 1st mark out spacing from centre line • 2nd take off half mitre thickness of hip • 3rd add on half thickness of common rafter • You now have long point • Continue to mark out other creepers

  11. Pattern Rafter – page 347 or handout

  12. Bevels – common rafters & centering rafters – from P 333 Plumb bevel Rise Level bevel ½ span

  13. Bevels - hips • Create another triangle in the roof Plumb bevel Level bevel Rise Plan length hip

  14. Bevels - hip • Relate to true length per metre again • As you do for common rafter

  15. Bevels – hip (eg) 30° pitch • Rise per m run – tan 30° = .577 • Use Pythagoras to create plan length of hip • √1.0² + 1.0² = 1.414 (plan length of hip) • True length per 1.414 run • √1.414² + .577² = 1.527

  16. Bevels - hip • You have now created that new triangle • You can reduce this to fit steel square • Take bevels from this True length 1.527 Rise .577 Plan length hip 1.414

  17. Bevels • You now have your first four bevels • Plumb bevel common rafter • Level bevel common rafter • Plumb bevel hip • Level bevel hip • In a hipped roof, there are eight (8) bevels all up

  18. Bevels • These 8 bevels can be developed in a number of ways • Eventually you’ll choose which one suits you • Geometric (we will draw ourselves) • Steel square (from P339 text) • Direct method (from P343 in text) • Or combined triangles (not in text) • We will cover each one separately, one by one later

  19. Main Roof Components • 1st lets concentrate on what we know • Common rafters • Centering rafters • Hips • Creepers • ridge

  20. What we’ve done already • Common rafters – set out on pattern • Crown end rafters – set out on pattern • Creepers – set out on pattern • Hips – we need to look at further

  21. Hip rafters • Before you erect hip • You have to take into account • Reductions • Ref: P16

  22. Hips • 1st at the ridge the hip must be reduced in length • You can calculate it or • Measure it in place • In principle it is reduced as shown opposite • Hand out – shortening at “x”

  23. Hips • 2nd at the birdsmouth you must reduce as well • Calculations of length give you position at outside of plate • Typically you cut corner to give better seating • Therefore birdsmouth must be reduced to suit • Handout – shortening at “y”

  24. Hips • Set-out of birdsmouth on hip • Top of rafters, including hips, must be on the one plane • Set out of hip birdsmouth as opposite • See handout

  25. Hipped Roof • Now you can build the main structure of the roof • Edge bevels for creepers and hips we’ll show you in workshop • Purlins we’ll look at after we develop other bevels • Drawing boards next week

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