1. Oblique Hip Roof Pictures & Text from previous Trade notes – course 5158
M. S. Martin – June 2005
Revised – February 2008
Reviewed March 2011

2. First lets revise Hip Roofs
Your Ref: Advanced roof workbook Pages 4 to 6

3. Plumb Bevel Common Rafter Level Bevel Common Rafter Edge Bevel Creeper
Draw in creeper
Project up
Draw in level line 90° to true length
Join to create bevel
LL1
Rise R
30° Pitch
Plumb Bevel Hip
1) Measure Rise
2) Draw in Rise 90° to plan length hip
3) Join to create bevel
Level Bevel Hip
Edge Bevel Hip
1) Draw in crown end
2) Draw in level line 2, 90° to plan length hip
3) project across to true length of hip
4) Draw level line 90° to true length
5) Join to create bevel
Rise
LL2
Edge Bevel Purlin
LL2
LL1
Face Bevel Purlin
1) Draw line 90°to TLCR, 2) Project down to plan length hip at two points, 3) draw line out from PLH, 4) create bevel

4. Calc’s Page 5

5. Calc’s continued Order Length 1.133 x ( 4.210 + 0.450 + 0.150)
True length / m x (1/2 span + eave + brick & cavity)
1.133 x ( )
1.133 x 4.810
mm for plumb cut
Order 5.700m lengths

6. Now do calculation on page 6

7. P. 10 and 11 Comparing Roof Shapes
BEVELS
Bevels CR = Same
Creeper Bevels
Develop the Same
Oblique hip do twice
Edge bevel purlin = as above
Hip Bevels
Face bevel purlin
Edge bevel crown end = New bevel, same principles
ROOF
Hips bisect angle
Ridge in centre
Rafters 90º plates

8. Ridge Gathering Detail
Copy detail into student notes, top of page

9. Set out of members Add to text notes bottom of page
The first members marked on the top plates being the centre lines for crown end and centring rafters, with the remaining common and creeper rafters measured into and over from these members.

10. Set out continued Lengths of oblique end and offset established
(eg) Oblique end = 6.400m
Offset = 3.800m

11. Set out continued Copy into notes bottom of page
2) If the ridge was extended it would bisect the oblique end.
3) This point ‘x’ is transferred to the offset and bisects the offset
4) Half the oblique end is the radius of a semi-circle. XA = XC = XB. Therefore XC is equal to half the oblique end.

12. Position of Centring Rafter
Copy into notes
5) Distance BE = Half Oblique end minus half the offset
6) Distance DA = Half Oblique end plus half the offset

13. Position of Crown End Copy into notes
7) FB is equal to BE (similar triangles)

14. Creeper set out Copy into notes
8) Thickness of material marked on the centre lines and remaining creepers set out, into and over.

15. Establishing Bevels
Just like any other roof you have done, the bevels can be established in a number of ways, the oblique end is no different
Geometrically
Direct Method or
Steel square
Your first drawing will be to establish these bevels geometrically
Example on next slide