cpccca3009a construct advanced roofs oblique roof
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TRANSCRIPT
![Page 1: CPCCCA3009A Construct Advanced Roofs Oblique roof](https://reader036.vdocuments.site/reader036/viewer/2022081414/54b51d7c4a795959468b45ed/html5/thumbnails/1.jpg)
Oblique End & Skew End Roof
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Solve Angles x and y
Walls are parallel
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Solve Angles x and y
Walls are parallel
Determine relevant triangle
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Solve Angles x and y
Walls are parallel
Tan y = Opp/ AdjTan y = 2000 / 900
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Solve Angles x and y
Walls are parallel
Tan y = 2.222Angle y = 65.8⁰
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Solve Angles x and y
Walls are parallel
Angle Z =180 – 90 - 65.8⁰
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Solve Angles x and y
Walls are parallel
Angle Z = 24.2⁰
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Solve Angles x and y
Walls are parallel
Angle X = 24.2 + 90⁰ ⁰
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Solve Angles x and y
Walls are parallel
Angle X = 114.2⁰
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Oblique End Roof
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Determine Position of Centring Rafters
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Position Centring Rafter
If we extend ridge (which is central) it will intersect with centre of splay end
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Positioning Centring Rafter
Two Similar Triangles will be formed, 1 half the size of the other
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Positioning Centring RafterRemember for laterTherefore we can say the ridge extension length is half the length of the splay end extension
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Position Centring Rafters
Remember Hips MUST Bisect Corners
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Position Centring Rafters
Remember Hips MUST Bisect Corners(Angles will vary)
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Positioning Centring Rafterx90⁰ x
Corner is Bisected this must also = x
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Positioning Centring Rafterx90⁰ x
To form TriangleѲ = 180 – 90 – xѲ = 90 - x
Ѳ
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Positioning Centring Rafterx90⁰ x
Hip is at 90⁰ to Centring Rafters
90⁰ - x
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Positioning Centring Rafterx90⁰ x
Ѳ = 90⁰ – 90⁰ - x
90⁰ - x
Ѳ⁰
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Positioning Centring Rafterx90⁰ x
Ѳ = x
90⁰ - x
Ѳ⁰
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Positioning Centring Rafterx90⁰ x
To form triangleѲ =180⁰ - x – x = 180⁰ - 2x
90⁰ - x
x Ѳ
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Positioning Centring Rafterx90⁰ x
If the angles formed by a T intersection must total 180⁰Ѳ =180 ⁰ - (180⁰ - 2x) = 2x
90⁰ - x
x 180⁰ - 2x
Ѳ
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Positioning Centring Rafterx90⁰ x
Centring Rafters are at 90⁰ to Ridge & Wall Plates
90⁰ - x
x 180⁰ - 2x
2x
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Positioning Centring Rafterx90⁰ x
The internal angles of a 4 Sided polygon must total 360⁰
90⁰ - x
x 180⁰ - 2x
2x
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Positioning Centring Rafter90⁰
x
Ѳ = 360⁰ - 90⁰ - 90⁰ - 2x⁰ = 180⁰ -2x
90⁰ - x
x 180⁰ - 2x
2x
Ѳ
x
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Positioning Centring Rafter90⁰
Remember Hips bisect corners
90⁰ - x
x 180⁰ - 2x
2x
180⁰ - 2x
xx
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Positioning Centring Rafterx90⁰
Ѳ
Ѳ = 180⁰ - 2x 2 2 = 90⁰ - x
90⁰ - x
x 180⁰ - 2x
2x
180⁰ - 2x
Ѳ
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Positioning Centring Rafterx90⁰
90⁰ - x
Ѳ = 180⁰ - 2x 2 2 = 90⁰ - x
90⁰ - x
x 180⁰ - 2x
2x
90⁰ - x
x
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Positioning Centring Rafterx90⁰
90⁰ - x
Complete the TriangleѲ = 180⁰ - 90⁰ - (90⁰ - x) = x
90⁰ - x
x 180⁰ - 2x
2x
90⁰ - x
x
Ѳ
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Positioning Centring Rafterx90⁰
90⁰ - x
Angle between Rafters & Ridge is 90⁰ Ѳ = 90⁰ - x
90⁰ - x
x 180⁰ - 2x
2x
90⁰ - x
x
x
Ѳ
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Positioning Centring Rafterx90⁰
90⁰ - x
Angle between Hip RaftersѲ = 90⁰ - x + x = 90⁰
90⁰ - x
x 180⁰ - 2x
2x
90⁰ - x
x
x
90⁰ - x
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Positioning Centring Rafterx90⁰
90⁰ - x
Angle between Hip Rafters = 90⁰
90⁰ - x
x 180⁰ - 2x
2x
90⁰ - x
x
x
90⁰ - x
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Positioning Centring Rafterx
90⁰ -x
90⁰ x
90 90⁰ - x
x
90⁰
Therefore we can say1.When the corners of a splayed end roof are bisected they will intersect at the ridge
2.The angles formed by the hips will be 90⁰
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Positioning Centring Rafter
If we centre a circle on the intersection of the Ridge & skew end
Then make the diameter the lengthOf the skew end
The circle will pass thru the corners
=
=
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Positioning Centring Rafter
Lines from each end of a diameter that intersect on the circumference of the Circle will intersect at 90⁰
=
=
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Positioning Centring Rafter
If we extend lines from these intersectionsTo the centre of the circle
=
=
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Positioning Centring Rafter
If we extend lines from these intersectionsTo the centre of the circle
They must be radiuses
=
=
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Positioning Centring Rafter
The ridge line extended past the centringRafter must be a radius of this circle
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Positioning Centring Rafter
The Ridge Extension must equal the half length of the Splay end
=
=
=
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Positioning Centring Rafter
=
=
=
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Positioning Centring Rafter
Previously we determined that the length of The ridge extension was half the splay end extension
=
=
=
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Positioning Centring Rafter
Therefore the offset must equalRadius – Half Splay Extension
=
=
=
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Positioning Centring Rafter
Better we can sayHalf Splay End Length – Half Splay Extension
1097 – 450 = 647
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Positioning Centring Rafterx
90⁰ -x
90⁰ x
90 90⁰ - x
x
90⁰
Therefore we can sayIf External walls are parallel
Hips always bisect corners
1.When the corners of a splayed end roof are bisected they will intersect at the ridge
2.The angles formed by the hips will be 90⁰ (This is the same for a conventional roof)
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x90⁰
90 90⁰ - x
x
Solve Angle yDeveloping from last week
y
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x90⁰
90 90⁰ - x
x
1. Hips Always Bisect Corners
Solve Angle yDeveloping from last week
y
x
90⁰ - x
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x90⁰
90 90⁰ - x
x
1. Hips Always Bisect Corners2. Rafters are always at 90° to wall plates
Solve Angle yDeveloping from last week
y
x
90⁰
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x90⁰
90 90⁰ - x
x
1. Hips Always Bisect Corners2. Rafters are always at 90° to wall plates
Solve yDeveloping from last week
90 -x
x
90⁰This angle must = 90 - x
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x90⁰
90 90⁰ - x
Solve Crown End Run
90- x
x
90⁰
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x90⁰
90 90⁰ - x
Solve Crown End Run
90- x
90- x
This angle must be 90 - x
x
90⁰
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x90⁰
90 90⁰ - x
Solve Crown End Run
90- x
90- x
The angles in both these trianglesare the same
x
90⁰
90⁰
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x90⁰
90 90⁰ - x
Solve Crown End Run
90- x
90- x
Therefore these triangles are similar triangles
x
90⁰
90⁰
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x90⁰
90 90⁰ - x
Solve Crown End Run
90- x
90- x
The Hypotenuse of these triangles are the same
x
90⁰
90⁰
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x90⁰
90 90⁰ - x
Solve Crown End Run
90- x
90- x
The triangles are equal trianglesSo all sides will be equal
x
90⁰
90⁰
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x90⁰
90 90⁰ - x
Solve Crown End Run
90- x
90- x
Crown End Run = Half Span
x
90⁰
90⁰
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x90⁰
90 90⁰ - x
Solve Crown End Run
90- x
90- x
Crown End Run = Half Span
Crown End Rafter position willEqual same distance as CentringRafters from the short end
x
90⁰
90⁰
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Gathering Point
Similar to a conventional hip roof the gathering point is at the centreline of the Ridge & Centring rafters
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Gathering PointSimilar to a conventional hip roof the gathering point is at the centreline of the Ridge & Centring rafters
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Gathering Point
Similar to conventional hip roof all members that form the oblique end hip have the same rise as the common rafters
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Crown End Rafter Centreline Length
Similar to a conventional hip roof
The Crown End Rafters Centreline Run is the same as the common rafters
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Crown End Rafter Centreline Length
Similar to a conventional hip roof
The Crown End Rafters Centreline Rise is the same as the Common Rafters
The Crown End Rafters Centreline Run is the same as the Common Rafters
![Page 63: CPCCCA3009A Construct Advanced Roofs Oblique roof](https://reader036.vdocuments.site/reader036/viewer/2022081414/54b51d7c4a795959468b45ed/html5/thumbnails/63.jpg)
Crown End Rafter Centreline Length
The Centreline Line (CL) Length can be calculated in the same way
Crown CL = CL Run ÷ Cos PitchCrown CL = 1000 ÷ Cos 25⁰Crown CL =1000 ÷ 0.906Crown CL =1.103
Pitch 25⁰
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Crown End Rafter Centreline Length
The Centreline Line (CL) Length can be calculated in the same way
Crown CL = CL Run ÷ Cos PitchCrown CL = 1000 ÷ Cos 25⁰Crown CL =1000 ÷ 0.906Crown CL =1.103 (Note that this length also represents the length per metre
Pitch 25⁰
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Crown End Rafter Centreline Length using Pythagoras
The Centreline Line (CL) Length can be calculated in the same way
Crown CL = √(CL Run² + Rise²)Crown CL = √(1² + 0.466²)Crown CL = √(1 + 0.217) = √(1.217) Crown CL =1.103
Pitch 25⁰
![Page 66: CPCCCA3009A Construct Advanced Roofs Oblique roof](https://reader036.vdocuments.site/reader036/viewer/2022081414/54b51d7c4a795959468b45ed/html5/thumbnails/66.jpg)
The Centreline Line (CL) Length can be calculated in the same way
Crown CL = CL Run ÷ Cos PitchCrown CL = 1000 ÷ Cos 25⁰Crown CL =1000 ÷ 0.906Crown CL =1.103
Pitch 25⁰
Crown End Rafter Centreline Length using Trigonometry
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Crown End Rafter True Length
Similar to a conventional hip roof
The Crown End Rafters will butt into the Centring Rafters
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Crown End Rafter True Length
Different to a conventional hip roof
The Crown End Rafters do not butt into the Centring Rafters at 90⁰
![Page 69: CPCCCA3009A Construct Advanced Roofs Oblique roof](https://reader036.vdocuments.site/reader036/viewer/2022081414/54b51d7c4a795959468b45ed/html5/thumbnails/69.jpg)
Crown End Rafter True Length
The Centreline Line (CL) Length can be calculated in the same way
Crown CL = CL Run ÷ Cos PitchCrown CL = 1000 ÷ Cos 25⁰Crown CL =1000 ÷ 0.906Crown CL =1.103 (Note that this length also represents the length per metre
Pitch 25⁰
![Page 70: CPCCCA3009A Construct Advanced Roofs Oblique roof](https://reader036.vdocuments.site/reader036/viewer/2022081414/54b51d7c4a795959468b45ed/html5/thumbnails/70.jpg)
Crown End Rafter True Length
The Centreline Line (CL) Length can be calculated in the same way
Crown CL = √(CL Run² + Rise²)Crown CL = √(1² + 0.466²)Crown CL = √(1 + 0.217) = √(1.217) Crown CL =1.103
Pitch 25⁰