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

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Presentation on theme: "HIP ROOFS Created BY Michael Martin July 2004 / revised may 2007."— Presentation transcript:

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 Ridge Centring Rafters 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 1 st mark out spacing from centre line 2 nd take off half mitre thickness of hip 3 rd 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 Rise ½ span Plumb bevel Level bevel

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

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 +.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 Rise.577 Plan length hip True length 1.527

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 1 st 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 1 st 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 2 nd 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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