Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March...
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Transcript of Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March...
![Page 1: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/1.jpg)
Flat Roofs & Introduction to Gable Roofs
Ref:
M. S. Martin / March 2004 / Reviewed & Combined March 2007
![Page 2: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/2.jpg)
Review Ceiling Frame Calc’s
![Page 3: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/3.jpg)
Spec for example followingcopy on blank paper
• Joists 150 x 38 sawn Oregon @ 600mm centres, max. span 3.6m
• Trimmers 100 x 38 sawn Oregon @ 600mm centres
• Hanging beam 240 x 45 hardwood, max. span of 5.4m
• On sketch following, draw in joists and hanging beam to scale and indicate trimmer positions also.
![Page 4: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/4.jpg)
Sketch picture belowallow 100mm for wall frames (not shown)
Internal room sizes shown4.100
3.300
8.350
5.800
![Page 5: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/5.jpg)
Formula's
No. of joists = width of room - 1 spacing
Length of hanging beam = length of room + 2 x wall thickness
Trimmers = length of wall – 1 spacing
![Page 6: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/6.jpg)
Joists
8.350 – 1
.600
= 13.916 – 1
= say 14 – 1
= 13
Order 13 @ 6.0m
![Page 7: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/7.jpg)
Hanging beam
4.150 + .200 = 4.350
Order 1 @ 4.5m
![Page 8: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/8.jpg)
Trimmers
5.800 – 1 = 9.666 – 1
.600
Say 10 – 1 = 9
Trimmers at two ends plus internal wall
9 x 3 = 27, 27 x .600 = 16.2 lin/m
Order 2 @ 6.0m, 1 @ 4.2m
![Page 9: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/9.jpg)
Flat roof construction
• Section 8 – from P306
• Flat roofs combine the roof and ceiling frame in one
• Generally described as one with a pitch less than 10 deg.
• To allow for extra loads the rafters / ceiling jiosts are increased in sectional size
![Page 10: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/10.jpg)
Ceiling types
• Ceilings can be either lined on the rake or rafters laid flat and use graded battens to give fall to roof
![Page 11: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/11.jpg)
Variations to ceilings
![Page 12: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/12.jpg)
![Page 13: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/13.jpg)
![Page 14: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/14.jpg)
Skillion roofs - P308
• Single sloping roofs• Walls at either end of roof at different
heights• Internal walls parralell to end walls will
be at different heights• Walls at 90 deg. to end walls will taper
in height under the sloping rafters / joists
![Page 15: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/15.jpg)
Two ceiling designs
![Page 16: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/16.jpg)
Simplest method of marking
• With skillion roofs the simplest thing is to scribe the rafter over the supporting plates
![Page 17: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/17.jpg)
Lean – to – Roof constructionP309
• This type is constructed against an existing wall or other roof
• Simple extensions
• Carports
• Verandahs
• Awnings
![Page 18: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/18.jpg)
Rafter / Ceiling variations
• Common on carports, open exposed rafters
![Page 19: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/19.jpg)
Other types
![Page 20: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/20.jpg)
Calculation of skillion rafters
(eg) calculate the quantity of 125 x 50 rafters required for the roof 4.2m long and 2.7m wide, rafter spacings 600mm centres, the difference in height of plates is 900mm
Length of rafter = √ (run of rafter)² + (rise)²
No. of rafters = (length of building) + 1 spacings
![Page 21: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/21.jpg)
Answer – length of rafter
√ 2.7² + .900²
= √ 7.29 + .81
= √ 8.1
= 2.846 lin/m
Order 3.0m lengths
2.700
4.200
900
![Page 22: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/22.jpg)
Number of rafters
(4.200) + 1
.600
= 7 + 1
= 8
Order 8 @ 3.0m rafters
![Page 23: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/23.jpg)
Gable Roofs and Components
![Page 24: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/24.jpg)
Name the components (handout)
![Page 25: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/25.jpg)
Answers
Roof Tiles
Tile Battens
Top Plate
Fascia
CorniceCeiling Joist
Ceiling Lining
Strutting Beam
Internal Wall
BlockTop Plate
Soffit Bearer
StudSoffit Lining
Anti-ponding Board
Collar Tie
RafterRidge
Purlin
Strut
Hanging Beam
Purlin
Strut
![Page 26: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/26.jpg)
Gable roof definitions
• Roof span: Is the horizontal distance measured overall the wall plates
SpanPlate
Stud Section A-A
![Page 27: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/27.jpg)
Rise: Is the vertical height measured from the x – y line to where the upper edge of the rafters would intersect
Rise
![Page 28: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/28.jpg)
![Page 29: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/29.jpg)
Continue on roofs
Ridge
Rafter
Purlin
Hanging beamCeiling joist
Strut
![Page 30: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/30.jpg)
Set Out for Common Rafter
• Plumb cut is at the top of the triangle
• We reduce the centre line length of rafter by ½ the thickness of the ridge to get our true length
![Page 31: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/31.jpg)
• Birdsmouth has a maximum cut out of one third the rafter depth
• Level bevel is shown here at base of triangle
• Back of birdsmouth, is outside of frame and if you take a vertical line up, this is where it meets the x – y line
X-Y
LINE
![Page 32: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/32.jpg)
Set Out on Steel Square
• Calculate rise per m. run
• Transfer to steel square
Reduced rise
Reduced run
![Page 33: Flat Roofs & Introduction to Gable Roofs Ref: M. S. Martin / March 2004 / Reviewed & Combined March 2007.](https://reader038.fdocuments.net/reader038/viewer/2022110101/56649e795503460f94b79869/html5/thumbnails/33.jpg)
Set out pattern rafter
• By either stepping out with square, or by calculation