ROOFING BCGCA3007B
Types of Roofs
Types of Roofs
Types of Roofs
Problem No1 Calculate Underside of Beams
Problem No1 Calculate Underside of Beams
Exercise 2 – Draw in Hips & Valleys
Exercise 2
Review Principles of Roofing Ridges are Level Rafters run at 90⁰ to Wall Plate Hips & Valleys bisect all internal & external Corners Roof members are set out along centerlines
Common Rafter Main Roofing Member Calculated same method as Gable Spaced 450mm to 600mm for Tiled Roofs 600mm to 900mm for Sheet Roof Cut using a Pattern Rafter
Centering Rafter Layout Roofs are Set out by Centreline Centring Rafters Centering Rafters Set back by Half Span
Centering Rafter Layout Half Span Centering Rafters Set back by Half Span
Ridge Used to centre Rafters Length = Length – span + Rafter Thickness
Determine Ridge Length
Crown End Rafters Cut & Fitted Against Ridge Act as Opposing Braces Similar to Common Rafter Half Rafter is Deducted
Crown End Rafter Layout What is the Crown End Rafter Centreline Span? Crown End Rafters
Crown End Rafter Layout Ridge 140 x19 Rafter 90 x 45 Crown End Rafters CL Span is Half span CL Span is Half span
Crown End Rafter Layout What is the run of Centering Rafter & Crown End Rafter Ridge 140 x19 Rafter 90 x 45 Crown End Rafters CL Span is Half span CL Span is Half span
Crown End Rafter Layout What is the run of Centering Rafter & Crown End Rafter Centering Rafters Crown End Rafters Ridge Hip Rafters
Crown End Rafter Run deduct Half Centering Rafter Crown End Rafter Layout What is the run of Centering Rafter & Crown End Rafter Ridge 140 x19 Rafter 90 x 45 Centering Rafter Run Deduct Half Ridge Crown End Rafter Run deduct Half Centering Rafter
Crown End & Centering Rafter Run Crown End Rafter = Half Span – Half Centering Rafter Width Run Centering Rafter = Half Span – Half Ridge Width
Hip Rafter Runs From Corner to Intersection Crown End & Centering Rafter - Centerline Hips Bisect Corners Fixing and Locating of Creepers Distance above Birdsmouth is same as common rafters
Hip Rafter Layout Roofs are Set out by Centerline Bisects Corner Hip in Plan
Hip Rafter Span of Hip
Hip Rafter Hip Run Hip Span
Hip Rafter Hip Run Hip Span
Hip Rafter Hip Run Hip Span
Hip Rafter Corner Trimmed to allow a better fit Hip Run Hip Span
Hip Rafter
Hip Rafter Layout Roofs are Set out by Centerline Bisects Corner Determine Centreline Span of Hip
Centreline Span of Hip (Z) X = Half span = 2070 Z = √(x2) + (x2) = √(20702) + (20702) Z = 2927 X = Half span = 2070 Z = Half span x √2 Z = 2927
Centreline Span of Hip (Z) X = Half span = 2070 Z = √(x2) + (x2) = √(20702) + (20702) Z = 2927 X = Half span = 2070 Z = Half span x √2 Z = 2927
Centreline Length of Hip Mathematically Methods Pythagoras Hip Centreline Length per Meter of Common Rafter Run Full Length Calculation
Hip by Pythagoras Pitch 25⁰ Step 1 – Calculate Roof Rise Rise = Tan 25⁰ x 2070 = 965mm
Hip by Pythagoras Pitch 25⁰ Hip Rise Must Be The Same Step 1 – Calculate Roof Rise Rise = Tan 25⁰ x 2070 = 965mm
Hip by Pythagoras Pitch 25⁰ Rise 965mm Hip Rise Must Be The Same as the rest of the roof Step 1 – Calculate Roof Rise Rise = Tan 25⁰ x 2070 = 965mm Hip Centreline Length = √(Hip Span² + Rise²) = √(2927² + 965²) = 3082mm What is the Hip Pitch ?
Hip by Pythagoras Pitch 25⁰ Rise = 965mm Hip CL = 3082 What is the Hip Pitch ? Using Tan Tan Pitch = Rise/ Hip Span Tan Pitch = 965/2927 Pitch = 18.25⁰ Using Cos Cos Pitch = Hip Span/ Hip CL Length Cos Pitch = 2927/3082
Centreline Length of Hip Mathematically Methods Pythagoras Hip Centreline Length per Meter of Common Rafter Run Full Length Calculation
Given Rise = 577 per metre From Gable Roof Lessons We Know That for the above Roof the Rafter Length per meter can be calculated as follows Rafter per meter run = √(1² + 0.577²) = 1.149
Given Rise = 577 per metre From Gable Roof Lessons We Know That for the above Roof the Rafter Length per meter can be calculated as follows Rafter per meter run = √(1² + 0.577²) = 1.149
Given Rise = 577 per metre We learnt previously that for every run of the common rafter the hip run is 1.414
Given Rise = 577 per metre We learnt previously that for every 1meter run of the common rafter the hip run is 1.414
Given Rise = 577 per metre Using Pythagoras we determine the above triangle Hip per meter of Common Rafter Run = √(1.414² + 0.577²) = 1.527
Given Rise = 577 per metre Using Pythagoras we determine the above triangle Hip per meter of Common Rafter Run = √(√2² + 0.577²) = √(2+ 0.577²) = √(2.333) = 1.527 We can now say that at this given rise per meter, for every meter of run of the common rafter the hip length will be 1527mm
Given Rise = 577 per metre Using Pythagoras we determine the above triangle Hip per meter of Common Rafter Run = √(√2² + 0.577²) = √(2+ 0.577²) = √(2.333) = 1.527 Therefore Halfspan = 2.070 CL Hip Rafter = 2.070 x 1.527 = 3.161
Pitch = 30⁰ Lets extend this principle Roof Pitch = 30⁰ Tan 30⁰ = 0.577
Pitch = 30⁰ This Triangle represents the Common Rafter Pitch Which by similar triangles we can transfer to our steel square Lets extend this principle Roof Pitch = 30⁰ Tan 30⁰ = 0.577 This Brings Our Triangle from The Previous Example Back
Pitch = 30⁰ We learnt previously that for every 1meter run of the common rafter the hip run is 1.414
Pitch = 30⁰ Using Pythagoras we determine the above triangle Hip per meter of Common Rafter Run = √(√2² x 1 + 0.577²) = √(2+ 0.577²) = √(2.333) = 1.527 Therefore for every meter of Common Rafter run at 30⁰ The Hip Centreline Length = 1.527
Calculate Hip Length per meter of Common Rafter Run
Calculate Hip Length per meter of Common Rafter Run