1. HIP ROOFS
Created BY Michael Martin July 2004 / revised may 2007 / reviewed & updated March 2010

2. Hip & Valley Roofs – P. 3 “4 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

3. Components – P. 12 Wall plate Ridge Centering rafter Crown end Hip
Common rafters
Creepers
Purlin
Etc. 1
Ridge board (Major roof) 9
Crown-end rafter 2
Collar tie 10
Creeper rafter 3
Common rafter 11
Valley rafter 4
Centring rafter 12
Ridge board (Minor roof) 5
Top plate 13
Common rafter (Minor roof) 6
Fascia 14
Valley creeper rafter 7
Hip rafter 15
Valley cripple creeper 8
Purlin 16
Trimmer for minor ridge fixing

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

5. Centering
rafter
Ridge
Centering rafter
Crown end rafter

6. New Members – summary to complete workbook section
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

7. Set out Ceiling frame also depends on set out of rafters
Set out as opposite
Textbook reference – P. 52
Set out of
rafters
Ceiling joists
Half span
Set out of
rafters
Half span

8. The Ridge for a hipped roof
Length = length of the building – width of building + rafter width

9. Pattern Rafters – P. 26 Now include Common / centering
Crown end rafter
Creeper rafters

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

11. Long point for 1st Creeper
Half thickness of Common Rafter
RIDGE
CROWN END RAFTER
Spacing
Half mitre thickness of Hip
CROWN END RAFTER
RIDGE
Half thickness Common rafter
Half mitre thickness hip
1st Creeper
CENTRING RAFTER
Spacing
Hip

12. Determining long point of creeper – P. 25
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
Look at next slide

13. Long point for 1st Creeper
Half thickness of Common Rafter
RIDGE
CROWN END RAFTER
Spacing
Half mitre thickness of Hip
CROWN END RAFTER
RIDGE
Half thickness Common rafter
Half mitre thickness hip
1st Creeper
CENTRING RAFTER
Spacing
Hip

14. Bevels for the Hip Roof

15. Bevels – common rafters & centering rafters – P. 37
Plumb bevel
Rise
Level bevel
½ span

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

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

18. 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

19. 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

20. 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 – plumb bevel common rafter, level bevel common rafter, plumb bevel hip, level bevel hip, edge bevel hip, edge bevel creeper, face bevel purlin & edge bevel purlin

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

22. One Example steel square – P. 46

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

24. 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

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

26. 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”

27. 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”

28. 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

29. 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