Broken Hip Roof.

Broken Hip Roof

Lay out of Broken Hip Roof
Roof Pitch = 25⁰ No new bevels need to be developed

Roof Pitch = 25⁰ All Bevels and edge cuts are the same as a hip roof Broken Hip As Span is not the same the rise will not be the same

Roof Pitch = 25⁰ Hip Rafter Minor Span Crown End Minor Span Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Common Rafter Major Span Common Rafter Minor Span Hip Rafter Major Span Valley Rafter Minor Span Centring Rafter Minor Span Crown End Major Span Crippled Centring Rafter Broken Hip Centring Rafter Major Span Gathering Point

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 1000/ Cos 25 = Determine Centreline Length Common Rafter Major Span =

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span =1103

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 675/ Cos 25 = Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span =

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Tan 25 x 1000 = Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof =

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Tan 25 x 675 = Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof =

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 =√(Rafter² + ½ Span²) √(1.103² + 1²) = Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span =

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 =√(Rafter² + ½ Span²) √(0.745² ²) = Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span =

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span = 0.897

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 =Same as Rise Major Span Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span = 0.897 Hip Rise Major Span =

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span = 0.897 Hip Rise Major Span = 466

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 =Same as Rise Minor Span Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span = 0.897 Hip Rise Major Span = 466 Hip Rise Minor Span =

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span = 0.897 Hip Rise Major Span = 466 Hip Rise Minor Span = 315

Roof Pitch = 25⁰ = 450/Cos 25 = 497 Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span = 0.897 Hip Rise Major Span = 466 Hip Rise Minor Span = 315 Creeper Shortening =

Roof Pitch = 25⁰ = Length – (Hip Ends x( ½ Span + ½ Rafter) = – (2 x ( ) =1569 Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span = 0.897 Hip Rise Major Span = 466 Hip Rise Minor Span = 315 Creeper Shortening = 497 Ridge Major Span

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span = 0.897 Hip Rise Major Span = 466 Hip Rise Minor Span = 315 Creeper Shortening = 497 Ridge Major Span = 1569

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 As both spans are the same pitch they are SIMILAR so Creeper Shortening is the same for both spans Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span = 0.897 Hip Rise Major Span = 466 Hip Rise Minor Span = 315 Creeper Shortening = 497

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 So the roofing members we have previously looked at are determined the same way Determine Centreline Length Common Rafter Major Span = 1103 Common Rafter Minor Span = 745 Rise Main Roof = 466 Rise Minor Roof = 315 Hip Length Major Span = 1.489 Hip Length Minor Span = 0.897 Hip Rise Major Span = 466 Hip Rise Minor Span = 315 Creeper Shortening = 497

Roof Pitch = 25⁰ To develop other Roofing Members we need to determine the plan length first Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Crippled Centring Rafter

Roof Pitch = 25⁰ To develop other Roofing Members we need to determine the plan length first Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Crippled Centring Rafter Distance Between Ridge Minor Span & Crippled Centring Rafter = Difference Between the two half spans = 325

Roof Pitch = 25⁰ To develop other Roofing Members we need to determine the plan length first Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Crippled Centring Rafter We recall that all hips & valleys bisect corners. In this building it means that they are at 45⁰.

Roof Pitch = 25⁰ To develop other Roofing Members we need to determine the plan length first Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Crippled Centring Rafter We recall that all hips & valleys bisect corners. In this building it means that they are at 45⁰. Therefore where the Broken Hip intersects the Ridge Minor Span must be 325mm from the Centreline of the Ridge Major Span

Roof Pitch = 25⁰ To develop other Roofing Members we need to determine the plan length first Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Crippled Centring Rafter As the valley is at 45⁰ the intersection with the valley must be a further 325mm

Roof Pitch = 25⁰ To develop other Roofing Members we need to determine the plan length first Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Crippled Centring Rafter Plan Centreline Length = 2 x (Half Span Major – Half Span Minor) 2 x (1000 – 675)

Roof Pitch = 25⁰ To develop other Roofing Members we need to determine the plan length first Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Determine Crippled Centring Rafter Plan Centreline Length = 2 x (Half Span Major – Half Span Minor) 2 x (1000 – 675) = 650

Roof Pitch = 25⁰ Develop True Length of Crippled Centring Rafter Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length = 650mm Deduct ½ Ridge Thickness = 17.5 mm Deduct/Add Long Point Correction

Roof Pitch = 25⁰ Develop True Length of Crippled Centring Rafter Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length = 650mm Deduct ½ Ridge Thickness = 17.5 mm Deduct/Add Long Point Correction Deduct ½ Hip x 1.414

Roof Pitch = 25⁰ Develop True Length of Crippled Centring Rafter Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length = 650mm Deduct ½ Ridge Thickness = 17.5 mm Deduct/Add Long Point Correction Deduct ½ Hip x =25mm Add ½ Rafter Thickness =

Roof Pitch = 25⁰ Develop True Length of Crippled Centring Rafter Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length = 650mm Deduct ½ Ridge Thickness = 17.5 mm Deduct/Add Long Point Correction Deduct ½ Hip x =25mm Add ½ Rafter Thickness = 17.5 True Length = 650 – 17.5 – Cos 25

Roof Pitch = 25⁰ Develop True Length of Crippled Centring Rafter Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length = 650mm Deduct ½ Ridge Thickness = 17.5 mm Deduct/Add Long Point Correction Deduct ½ Hip x =25mm Add ½ Rafter Thickness = 17.5 Long Point Correction = -7.5 mm True Length = 650 – 17.5 – Cos 25 True Length = = 690 mm to Long Pt (red) Cos 25

Roof Pitch = 25⁰ Plumb Cut for Crippled Centring Rafter Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Crippled Centring Rafter is in the same plane as the Common Rafters Therefore it must be the same pitch as the Common Rafters, so it must have the SAME PLUMB CUT AT BOTH ENDS

Roof Pitch = 25⁰ Edge Bevel for Crippled Centring Rafter Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 What Triangle forms the Bevel ?

Roof Pitch = 25⁰ Edge Bevel for Crippled Centring Rafter Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 What Triangle forms the Bevel

Simple Bevel Development
From Previous Plumb Bevel Rafter Level Bevel Rafter Edge Bevel Creeper Edge Bevel Purlin Plumb Bevel Hip Level Bevel Hip Edge Bevel Hip Face Bevel Purlin

Roof Pitch = 25⁰ Edge Bevel for Crippled Centring Rafter Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Edge Bevel for Crippled Centring Rafter is the CREEPER EDGE BEVEL The same is for Valley Creepers Crippled Creepers

Roof Pitch = 25⁰ Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Edge Bevel for Crippled Centring Rafter is the CREEPER EDGE BEVEL The same is for Valley Creepers Crippled Creepers It follows that all the The purlin bevels are The same as the hip end

Roof Pitch = 25⁰ Every Valley Creeper must have an opposing creeper Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35

Roof Pitch = 25⁰ Every Valley Creeper must have an opposing creeper Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 From previous calculations we determined the following

Roof Pitch = 25⁰ Every Valley Creeper must have an opposing creeper Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Centreline length is the same as distance from the gathering point

Roof Pitch = 25⁰ Every Valley Creeper must have an opposing creeper Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 To determine true length Long Pt Centreline length 325 Deduct ½ Ridge +/- Long Point Correction TL = 300/cos 25 =

Roof Pitch = 25⁰ Every Valley Creeper must have an opposing creeper Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 To determine true length Long Pt Centreline length 325 Deduct ½ Ridge +/- Long Point Correction TL = 300/cos 25 = (RED) NOTE - Long Point Correction will be the same if the Valley & Rafter are the same thickness

Roof Pitch = 25⁰ Determine Centreline Length Broken Hip Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35

Roof Pitch = 25⁰ Broken Hip Run 325 x = 460 Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35

Roof Pitch = 25⁰ Rise will be the difference between each span Hip Run = 460 Rise Main Roof = 466 Rise Minor Roof = 315 = 151

Roof Pitch = 25⁰ Rise will be the difference between each span Hip Run = 460 Rise Main Roof = 466 Rise Minor Roof = 315 = 151 Broken Hip = √(460² + 151²) =

Roof Pitch = 25⁰ Rise will be the difference between each span Hip Run = 460 Rise Main Roof = 466 Rise Minor Roof = 315 = 151 Broken Hip = √(460² + 151²) = 484 Pitch = Tan-1 (151/460) = Tan-1 (0.328) = 18.17⁰

Roof Pitch = 25⁰ Determine True Length Broken Hip Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35

Roof Pitch = 25⁰ Determine True Length Broken Hip Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length =

Roof Pitch = 25⁰ Determine True Length Broken Hip Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length = 460 Deduct Hip End Reduction = ½ Crown End x 1.414 ½ Hip Thickness

Roof Pitch = 25⁰ Determine True Length Broken Hip Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length = 460 Deduct Hip End Reduction = -42

Roof Pitch = 25⁰ Determine True Length Broken Hip Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length = 460 Deduct Hip End Reduction = -42 Deduct / Add Long Point Correction = less ½ Ridge x = - 25 add ½ Hip Thickness = +17.5 = -7.5

Roof Pitch = 25⁰ Determine True Length Broken Hip Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length = 460 Deduct Hip End Reduction = -42 Deduct / Add Long Point Correction = less ½ Ridge x = - 25 add ½ Hip Thickness = +17.5 = -7.5 True Run = – 7.5 = 411.5

Roof Pitch = 25⁰ Hip Pitch 18.17⁰ Determine True Length Broken Hip Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35 Plan Centreline Length = 460 Deduct Hip End Reduction = -42 Deduct / Add Long Point Correction = less ½ Ridge x = - 25 add ½ Hip Thickness = +17.5 = -7.5 True Run = – 7.5 = 411.5 True Length Long Point = 411.5/ Cos 18.17 = 433mm

Roof Pitch = 25⁰ Plumb cut is the same as the hip Edge Bevels are the same as the hip Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35

Roof Pitch = 25⁰ With the more complex roof. It is important to plan & set out the basic frame of the roof. Rafter 90 x 450 c to c Hip Rafters 140 x 35 Ridge 140 x 35

Broken Hip Roof.

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Broken Hip Roof.

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