cpccca3009a construct advanced roofs octagonal end roof
DESCRIPTION
TRANSCRIPT
Octagonal Roof
Walls are parallel
Draw Crown Rafters
Set Back ½ Rafter Thickness
Draw & Bisect Crown End Rafter
Draw Tangents to the Crown Ends
Draw Top Plate
Clean Up Drawing
Clean Up Drawing
Angle Between Major Crown End & Centring Rafters = 90⁰
Clean Up Drawing
Angle Between Crown End Rafters = 45⁰
Clean Up Drawing
Angle Between Crowns Ends & Hips = 22.5⁰
Angles formed by the Roof
These angles are the same no matter the size of Roof as it is a Geometric Shape
Length Of Octagonal EndsIf the angle between the members is constant 22.5⁰
We can say in all cases, no matter the size of the roof½ End = ½ Span x tan 22.5⁰
= ½ Span x 0.414 (tan 22.5⁰ is always used)
If the angle between the members is constant 22.5⁰
We can say in all cases, no matter the size of the roof
½ End = ½ Span x 0.414
Length Of Octagonal Ends
If the angle between the members is constant 22.5⁰
In all cases, we can say
Full End = ½ Span x 0.414 x 2
Length Of Octagonal Ends
If the angle between the members is constant 22.5⁰
Also in all cases, the full end will be
Full End = ½ Span x 0.828
Length Of Octagonal Ends
These formulas are the same no matter the size of the Roof
½ End = ½ Span x 0.414Full End = ½ Span x 0.828
Length Of Octagonal Ends
These formulas are the same no matter the size of the Roof
Calculating Centring rafters and Crown End Rafter use the same method as a normal hip roof
Major Crown End Rafter
These formulas are the same no matter the size of the Roof
Calculating Centring rafters and Crown End Rafter use the same method as a normal hip roof
Major Crown End Rafter
These formulas are the same no matter the size of the Roof
Minor Crown End Rafters join in a similar manner to a hip rafter
Minor Crown End Rafters
These formulas are the same no matter the size of the Roof
Minor Crown End Rafters join in a similar manner to a hip rafter
Minor Crown End Rafters
The Plan run of the minor crown is reduced by ;
½ Centring Rafter x 1.414
These formulas are the same no matter the size of the Roof
Minor Crown End Rafters join in a similar manner to a hip rafter
Minor Crown End Rafters
Minor Crown = ½ Span x ½ C.R Thickness÷
Edge Bevel Minor Crown End Rafters
Plan Angle = 45⁰
Edge Bevel Minor Crown End RaftersPlan Angle
Plan Angle = 45⁰
Plan Angle = 90⁰
Edge Bevel Minor Crown End RaftersPlan Angle
Plan Angle = 45⁰
Plan Angle = 90⁰
Both Sides MustBe Equal
Edge Bevel Minor Crown End RaftersPlan Angle
Plan Angle = 45⁰
Plan Angle = 90⁰
Both Sides MustBe Equal
When Can You Use The Plan For the Edge Bevel ?
Edge Bevel Minor Crown End RaftersTrue Angle