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 = (plan length of hip)
True length per run
√1.414² ² = 1.527

16. Bevels - hip True length 1.527 Rise .577 Plan length hip 1.414
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