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Gable Roof BCGCA3007B

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Gable Roof Flush with no eaves Flush with raked eaves Boxed

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**Flush Gable (No Eaves) Rafter finishes in line with end wall**

Barge fixed to outside wall No Overhang Studwork to take sheeting or support brickwork Not required to support roof

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**Flush Gable with Raked Eaves**

Ridge Extends to Form Eave Verge Trimmers to Support Gable Rafter Trimmers to Support Verge Trims and Roof Battens Gable Stud supports Second Rafter Brick Work or Wall Lining Second Rafter to Support Verge Trims Roof Extends to Form eave Top Plate may be extended to support Rafter

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**Boxed Gable Verge Rafter Gable Studs & Sheeting**

Purlin & Lintel Extended to Support Verge Rafter Minimum Back span 2 x Overhang Design 3 x Overhang Base of Gable Lined & Level with U/S of Eaves

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**Verges Is the Junction of the Roof and the Barge/Verge Board**

Verge Detail for Tiled Roof

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**Verge Detail for Sheet Metal Roof**

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**Principles of Roofing Ridges are Level**

Rafters run at 90 to wall plates Hips & Valleys bisect all internal & external Corners Roof members are set out along centerlines

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**Roofing Members Ridge Common Rafter Collar Tie Top Plate Hanging Beam**

Purlin Top Plate Strutting Beam Strut Ceiling Joist Strut

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**Roof Members Common Rafter – Main Sloping Roof Member**

Spacing 450mm or 600mm for Tiled Roofs 900mm for tiled roofs Supports Roof Battens which in turn support roof coverings Must be in single lengths or joined over supports Fixings (Nominal) 2 x 75mm Skew & 2 x 75mm into Ceiling Joist (if joist is > 38, 90mm Nails)

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**Roofing Members Ridge Common Rafter Collar Tie Top Plate Hanging Beam**

Purlin Top Plate Strutting Beam Strut Ceiling Joist Strut

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**Ridge Highest Part of the Roof Will run full length of Gable Roof**

Runs Parallel to TOP PLATE Fixes Rafters at Top of Roof Rafters are nailed either side and not offset by more than 1 thickness In Uncoupled Roof, they act as beams Nailed to Rafters with 2 x 75mm Nails

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Joining Ridge Boards

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**Roofing Members Ridge Common Rafter Collar Tie Top Plate Hanging Beam**

Purlin Top Plate Strutting Beam Strut Ceiling Joist Strut

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**Purlin Also known as Underpurlin Fixed to Underside of RAFTER**

Runs parallel to ridge and wall plates Reduce span of RAFTER Will run full length of Gable Roof

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**Roofing Members Ridge Common Rafter Collar Tie Top Plate Hanging Beam**

Purlin Top Plate Strutting Beam Strut Ceiling Joist Strut

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Struts Transfer Loads From Purlins to Load Bearing Walls

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**Also Known as Barrap Straps**

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**Roofing Members Ridge Common Rafter Collar Tie Top Plate Hanging Beam**

Purlin Top Plate Strutting Beam Strut Ceiling Joist Strut

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Collar Ties

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Gable Roof Common Rafter

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**Common Rafter Main Roofing Member Calculated same method as Gable**

Spaced Usually at 450mm to 600mm for Tiled Roofs & 600mm to 900mm for Sheet Roof Cut using a Pattern Rafter

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Gable Roof Common Rafter Top Plate

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**Top Plate Top Part of the Wall Frame**

Takes structural load from Roof and Transfers it to the wall studs Size must be determined from span tables

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Pitching Line Pitching Line

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Pitching Line Pitching Line Starts at top corner of Top Plate

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Pitching Line Pitching Line Starts at top corner of Top Plate

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**Pitching Line Pitching Line Starts at top corner of Top Plate**

Pitching line Runs Parallel to top of Rafter

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**Pitching Line Pitching Line Starts at top corner of Top Plate**

Pitching line Runs Parallel to top of Rafter This establishes the Pitch of the Roof

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**Pitching Line Pitching Line Starts at top corner of Top Plate**

If the pitching line went from top plate to top of roof the pitch is not correct or relevant. As you will see later it would make our calculations far harder

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**Common Rafter Principles**

Span – From Birdsmouth to Birdsmouth Half Span – From Birdsmouth to Centre

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**Common Rafter Principles**

Rise – Vertical height from top plate to intersections of pitching lines at Apex Rise is NOT measured to top of Rafter

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**Common Rafter Principles**

If Rise is taken from Top Plate to Apex pitch will be incorrect

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**Common Rafter Principles**

Measured to edge of Ridge Measured to centre of Ridge

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**Confirmation of Learning**

Mark on Drawing in Workbook where, Centreline Length is measured to

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Centreline Length Centre Line Length

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**Confirmation of Learning**

Mark on Drawing in Workbook where, True Length is measured to Centre Line Length

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**Common Rafter Principles**

Centre Line Length True Length True Length is usually what we need

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**Confirmation Of Learning**

Mark on Drawing in Workbook where, Rafter is measured from at Base

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**Measurement of Rafter Mark on Drawing in Workbook where,**

Rafter is measured from at Base Rafter is measured from this point

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**Confirmation Of Learning**

Mark on Drawing in Workbook where, The Rafter Length is measured

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**Measurement of Rafter Mark on Drawing in Workbook where,**

The Rafter Length is measured The Rafter Length is measure along the pitching line

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**Measurement of Rafter Mark on Drawing in Workbook where,**

The Rafter Length is measured You may also measure on any line that is parallel to the pitching line so long as it is between Plumb lines that pass thru the required points.

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**Determine Rafter Length Mathematically**

For every roof you must solve the 1m triangle based on the roof pitch Rafter 90 x 45 Ridge 125 x 19

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The “1 Metre Triangle”

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**Step 1 - Solve 1m Triangle Rafter Length per 1 metre of Plan length**

Rise per 1 metre of Plan Length 25° This is the a triangle based on the roof pitch Plan Length of 1 metre

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**Step 1 - Solve 1m Triangle Rafter Length per 1 metre of Plan length**

Rise per 1 metre of Plan Length 25° This is always no matter what the Roof Pitch is Plan Length of 1 metre

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Step 1 - Solve 1m Triangle These dimension will always change and are dependant on the Roof Pitch. These figures will need to be determined by you. Rafter Length per 1 metre of Plan length Rise per 1 metre of Plan Length 25° Plan Length of 1 metre

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Step 1 - Solve 1m Triangle Solve all Unknown Sides of the a triangle based on the roof pitch Unknown Unknown 25° 1.000 Horizontal Travel = “Plan Length”

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Step 1 - Solve 1m Triangle Solve all Unknown Sides of the a triangle based on the roof pitch Unknown 0.466 Rise = Plan Length x Tan (Pitch)° = x Tan 25° = 0.466 25° 1.000 Horizontal Travel = “Plan Length”

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Step 1 - Solve 1m Triangle Rafter Length / m = Plan Length ÷ Cos (Pitch)° = ÷ Cos 25° = ÷ = 1.103 Solve all Unknown Sides of the a triangle based on the roof pitch 1.103 0.466 Rise = 1 x Tan 25° = 0.466 25° 1.000 Horizontal Travel = “Plan Length”

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**Step 1 - Solved 1m Triangle**

For any roof of 25° the Rafter Length per 1 m of Plan Length For any roof of 25° the Rise per 1 m of Plan Length 1.103 0.466 25° 1.000 Horizontal Travel = “Plan Length”

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**Confirmation of Learning**

Determine the following 1 metre triangles 16° 20° 45° 30°

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**Confirmation of Learning**

Determine the following 1 metre triangles 1.064 1.040 0.287 0.364 16° 20° 1.000 1.414 1.000 1.155 0.577 45° 30° 1.000 1.000

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**Determine Centreline Length**

Ridge Centreline Length is to the Centre of the Roof ½ Span

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**Definition – Plan Length**

“Plan Length” is the Horizontal (Level) Distance a Roofing Member Travels A Rafter is 3310 and is pitched at 25° 3310 25° Plan Length

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**Definition – Plan Length**

Plan Length is the Horizontal (Level) Distance a Roofing Member Travels 3310 The Horizontal Distance that the Rafter Travels is its “PLAN LENGTH In this case is 3000 25° 3000

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**Definition – Plan Length**

Plan Length is the Horizontal (Level) Distance a Roofing Member Travels 3310 It is important when determining any Rafter Hip Creeper Valley etc., To first determine its plan length 25° 3000

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**Confirmation Of Learning**

What is the “Plan Length” of this Rafter? 2750 1887 2000

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**Confirmation Of Learning**

What is the “Plan Length” of this Rafter? 2750 1887 2000 This is the plan length

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Centreline Length What is the plan length we need to use to determine the Centreline Length of the common rafter below ? Rafter 90 x 45 Ridge 125 x 19

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Centreline Length What is the plan length we need to use to determine the Centreline Length of the common rafter below ? Rafter 90 x 45 Ridge 125 x 19

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**Step 2 – Determine Plan Length Centreline Length**

Determine how far the rafter travels HORIZONTALLY PLAN LENGTH 1.103 0.466 25° 1350(1/2 Span) Plan Length 1 “Plan Length” = ½ Span = 1350

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**Step 2 – Determine Plan Length Centreline Length**

Determine how far the rafter travels HORIZONTALLY PLAN LENGTH 1.103 0.466 25° 1350(1/2 Span) Plan Length 1 For any Rafter (or Hip) you must first determine the Horizontal Travel i.e. PLAN LENGTH “Plan Length” = ½ Span = 1350 Plan Length= 1350

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**Principle Of Similar Triangles**

If all 3 angles of 2 triangles are equal There will be the same proportional difference between the corresponding sides of the triangle 65° 2.206 2x 1.862 1.103 65° 0.466 25° 25° 1 2 The right hand triangle is 2x the size of the “1 meter triangle”

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 This is our “1 meter” triangle

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 This is the TARGET triangle formed by the rafter

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 The first step is to determine proportional ratio between the triangles

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 Target Triangle 1 Metre Triangle The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths Ratio = Plan length of “TARGET” triangle ÷ Plan length “1 metre” triangle

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths Ratio = Plan length of TARGET triangle ÷ Plan length “1 meter” triangle Ratio = 2 ÷ 1 Ratio = 2

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths Ratio = Plan length of TARGET triangle ÷ Plan length “1 meter” triangle Ratio = 2 ÷ 1 Ratio = 2 We will call this the triangle multiplier

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths Ratio = Plan length of TARGET triangle ÷ Plan length “1 meter” triangle Ratio = 2 ÷ 1 Ratio = 2 For the Common Rafter as we use the “1 meter” triangle, the Triangle Multiplier will always = Plan length of the Target triangle

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**Step 3 – Determine Rafter Length Centreline Length**

1489 1.103 0.466 25° 1350 ½ Span Plan Length 1 Rafter Length = Plan Length x Rafter Length per metre (RL/m) Rafter Length = x 1.103 Rafter Length = 1489

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**Step 4 – Determine Rise (If Required) Centreline Length**

1489 629 1.103 0.466 25° 1350 (1/2 Span) Plan Length 1 Total Rise = Horizontal Travel x Rise per metre Total Rise = 1350 x 0.466 Total Rise = 629

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True Length What is the plan length we need to use to determine the True Length of the common rafter below ? Rafter 90 x 45 Ridge 125 x 19

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True Length What is the plan length we need to use to determine the True Length of the common rafter below ? Rafter 90 x 45 Ridge 125 x 19

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**Determine Centreline Length**

Ridge 125 x19 True Length is to the Side of the Ridge ½ Span – ½ Ridge Thickness

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**Step 2 – Determine Plan Length True Length**

Ridge 125 x 19 Determine how far the rafter travels HORIZONTALLY PLAN LENGTH 1.103 0.466 25° 1341 Plan Length 1 “Plan Length” = ½ Span – ½ Ridge Thickness = 1350 – 9.5 = 1341

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**Step 2 – Determine Plan Length Trur Length**

Ridge 125 x 19 Determine how far the rafter travels HORIZONTALLY PLAN LENGTH 1.103 0.466 25° 1350(1/2 Span) Plan Length 1 For any Rafter (or Hip) you must first determine the Horizontal Travel i.e. PLAN LENGTH “Plan Length” = 1341

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**Principle Of Similar Triangles**

If all 3 angles of 2 triangles are equal There will be the same proportional difference between the corresponding sides of the triangle 65° 2.206 2x 1.862 1.103 65° 0.466 25° 25° 1 2 The right hand triangle is 2x the size of the “1 meter triangle”

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 This is our “1 meter” triangle

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 This is the TARGET triangle formed by the rafter

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 The first step is to determine proportional ratio between the triangles

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 Target Triangle 1 Metre Triangle The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths Ratio = Plan length of “TARGET” triangle ÷ Plan length “1 metre” triangle

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths Ratio = Plan length of TARGET triangle ÷ Plan length “1 meter” triangle Ratio = 2 ÷ 1 Ratio = 2

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths Ratio = Plan length of TARGET triangle ÷ Plan length “1 meter” triangle Ratio = 2 ÷ 1 Ratio = 2 We will call this the triangle multiplier

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**Understanding the Principle Of Similar Triangles**

65° 2.206 1.862 1.103 65° 0.466 25° 25° 1 2 The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths Ratio = Plan length of TARGET triangle ÷ Plan length “1 meter” triangle Ratio = 2 ÷ 1 Ratio = 2 For the Common Rafter as we use the “1 meter” triangle, the Triangle Multiplier will always = Plan length of the Target triangle

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**Step 3 – Determine Rafter Length True Length**

1479 1.103 0.466 25° 1341 Plan Length 1 Rafter Length = Plan Length x Rafter Length per metre (RL/m) Rafter Length = x 1.103 Rafter Length = 1479

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**Step 4 – Determine Rise (If Required) Centreline Length**

1479 625 1.103 0.466 25° 1341 Plan Length 1 Total Rise = Horizontal Travel x Rise per metre Total Rise = 1341 x 0.466 Total Rise = 625

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**Overhang on a Plan is always measured from external wall**

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**Determine Rafter Length Mathematically (Version 1)**

In this case Timber Famed Wall Determine Rafter Length per m = 1 ÷ cos 25 = per m Rafter = Run x 1.103 = x 1.103 = 1.480 Roofing calculations are always measured from Birdsmouth or pitching point Rafter 90 x 45 Ridge 125 x 19

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**Determine Rafter Length Mathematically**

In this case Timber Famed Wall Determine Total Rafter Length Rafter = Plan Length x 1.103 = x 1.103 = 1791 x 1.103 = 1.975 Roofing calculations are always measured from Birdsmouth or pitching point Rafter 90 x 45 Ridge 125 x 19

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**Determine Rafter Length Mathematically**

In this case Brick Veneer Wall O/H = = 600mm Total Rafter Length = x 1.103 = 1961 x 1.103 = 2.163 Rafter 90 x 45 Ridge 125 x 19

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**Determine Rafter Length Graphically**

Draw Roof Full-size Measure members directly Avoid using scaled drawing Scale use only for angles Rafter 90 x 45 Ridge 125 x 19

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**Determine Rafter Length Mathematically**

In this case Timber Famed Wall O/H = 450 / cos 25 = 497mm Roofing calculations are always measured from Birdsmouth or pitching point Rafter 90 x 45 Ridge 125 x 19

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**Determine Rafter Length Mathematically**

In this case Brick Veneer Wall O/H = cos 25 = 662mm Total Rafter Length Timber Frame = = 1977mm Brick Veneer = = 2142mm Rafter 90 x 45 Ridge 125 x 19

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**Determine Rafter Length Graphically**

Draw Roof Full-size Measure members directly Avoid using scaled drawing Scale use only for angles Rafter 90 x 45 Ridge 125 x 19

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**Determine Rafter Length Using Roofing Square**

Use Calculator Press Tan 25 – what does this give you Therefore for every 1 metre run there is 0.466m rise Using the principle of similar triangles we half the size of the triangle

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**Press Tan 25 – what does this give you **

Use Calculator Press Tan 25 – what does this give you Therefore for every 1 metre run there is 0.466m rise Using the principle of similar triangles we half the size of the triangle

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**Press Tan 25 – what does this give you **

Use Calculator Press Tan 25 – what does this give you Therefore for every 1 metre run there is 0.466m rise Using the principle of similar triangles we half the size of the triangle

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**Using Similar Triangles**

1341/500 = or = 2 r 341

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**Using Similar Triangles 1341/500 = 2.682 or = 2 r 341**

Step out 2 full triangles Select Start Point Allowing for O/H

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**Intersection of Top of Rafter & Edge of Square**

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**Using Similar Triangles 1341/500 = 2.682 or = 2 r 341**

Step out 341 & use square to extend Step out 2 full triangles Select Start Point Allowing for O/H

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**Determine Roofing Angles used in Gable Roofs**

Plumb Cut Foot Cut

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**Determining Angles with Roofing Square**

When we set out rafter previously we determined plumb cut

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**Determining Angles with Roofing Square**

Plumb Cut Foot Cut

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**Determining Angles Mathematically**

Extend Line 90⁰ From Rafter

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**Determining Angles Mathematically**

Extend Line 90⁰ From Rafter Extend Plumb Line

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**Determining Angles Mathematically**

Extend Line 90⁰ From Rafter Extend Plumb Line Angle Formed is same as roof pitch

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**Determining Angles Mathematically**

This angle must be 65⁰ 90 – 25 = 65 Right Angled Triangle Roof Pitch This angle must be 25⁰ 90 – 65 = 25

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**Determining Angles Mathematically**

Extend Line 90⁰ From Rafter

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**Determining Angles Mathematically**

Extend Line 90⁰ From Rafter Extend Plumb Line from same origin at top of Rafter

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**Determining Angles Mathematically**

Extend Line 90⁰ From Rafter Extend Plumb Line from same origin at top of Rafter Angle Formed is same as roof pitch

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**Determining Angles Mathematically**

Extend Line 90⁰ From Rafter Extend Plumb Line Angle Formed is same as roof pitch Offset = Tan (pitch) x width

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**Determining Angles Mathematically**

Extend Line 90⁰ From Rafter Extend Plumb Line Angle Formed is same as roof pitch Offset = Tan (25⁰) x = 42

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**Determining Angles Mathematically**

Next we can Determine our Birdsmouth Width across plumb cut = 90/ cos 25 = 99 Therefore max Birdsmouth = 33 Distance from top plate to top of Rafter = 66

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Complete Q5 in Workbook

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**Determine Roof Angles Graphically**

Plan – View We can only see rafter run

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**Determine Roof Angles Graphically**

Extend Top Plate & Ridge

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**Determine Roof Angles Graphically**

Extend Top Plate & Ridge Mark Rise

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**Determine Roof Angles Graphically**

Plumb Cut Extend Top Plate & Ridge Mark Rise Draw Hypotenuse Foot Cut

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**Steps In Construction Gable Roof**

Physically Confirm Span & Plates are Parallel Calculate True Rafter, Rise & Plumb cuts Mark out ceiling joists, rafters & ridge Install Ceiling Joists Cut Pattern Rafter & test to confirm Cut required rafters & install

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**Estimating Gable Roof - Rafter From Previous Ceiling Estimate**

Pitch = 25⁰ Determine No of Ceiling Joists 12 250/ 600 = = = Therefore 22 set of Rafters = Verge = 48

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**Determine Rafter Length**

Span = 6900 Pitch 24°

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**Determine Rafter Length**

Span = 6900 Pitch 24° 1

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**Determine Rafter Length**

Span = 6900 Pitch 24° 0.4451 1

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**Determine Rafter Length**

Span = 6900 Pitch 24° Rafter =√ ( ) 0.4451 1

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**Determine Rafter Length**

Span = 6900 Pitch 24° 1.095 Rafter =√ ( ) = 1.095 0.4451 1

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**Determine Rafter Length**

Span = 6900 Pitch 24° Rafter = 1

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**Determine Rafter Length**

Span = 6900 Pitch 24° 1.095 Rafter =1 ÷ Cos 24° 1

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**Determine Rafter Length**

Span = 6900 Pitch 24° 1.095 Rafter =1 ÷ Cos 24° = 1.095 1

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**Determine Rafter Length**

Span = 6900 Half Span = 3450

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**Determine Rafter Length**

Span = 6900 Half Span = 3450 Run = 3450 – 9.5 (Half Ridge) =

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**Determine Rafter Length**

Span = 6900 Half Span = 3450 Run = 3450 – 9.5 = True Length = / cos 24 =3766

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**Determine Rafter Length**

Span = 6900 Half Span = 3450 Run = 3450 – 9.5 = True Length = / cos 24 =3766 Overhang = 450/cos 24 = 493

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**Determine Rafter Length**

Span = 6900 Half Span = 3450 Run = 3450 – 9.5 = True Length = / cos 24 =3766 Overhang = 450/cos 24 = 493 Total Rafter = 4259

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**Determine Rafter Length**

Span = 6900 Half Span = 3450 Run = 3450 – 9.5 = True Length = / cos 24 =3766 Overhang = 450/cos 24 = 493 Total Rafter = 4259 Allow for plumb cut = 41 Minimum Rafter Length = 4300 Order = 4500 Allow for Plumb cut Tan (Pitch) x Width = Tan 24° x 90 = 41

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Estimating Sheet

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**Estimating Gable Roof - Purlin**

Pitch = 24⁰ Overhang 450 Rafter 90 x 45 F7 600 c to c Tiled Roof Ridge 140 x 19 Purlin 90 x 70 F7 Purlin Run full length of Roof Do we need purlins

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Span Required = 3766 Max Span 2600 3766/2600 = 1.4 Therefore 1 row required each side In First Instance we check single span Max Span = 1900

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**Estimating Gable Roof -Purlin**

Pitch = 24⁰ Overhang 450 Rafter 90 x 45 F7 600 c to c Tiled Roof with Flush Gable & Raking Eaves Ridge 140 x 19 Purlin 90 x 70 F7 Purlin Run full length of Roof Do we need purlins Purlins Run Full Length x 150 (Joins) =

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Estimating Sheet

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**Estimating Gable Roof - Ridge**

Pitch = 24⁰ Overhang 450 Rafter 90 x 45 F7 600 c to c Tiled Roof with Flush Gable & Raking Eaves Ridge 140 x 19 Purlin 90 x 70 F7 Ridge Runs Full Length x 450 (O/H) x 300 (allow for joins) =14000mm Note – For Flush eaves there is no O/H ridge = 12500 Boxed eaves will require O/H ridge = 13400mm

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Estimating Sheet

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**Estimating Gable Roof - Struts**

Pitch = 24⁰ Overhang 450 Rafter 90 x 45 F7 600 c to c Tiled Roof with Flush Gable & Raking Eaves Ridge 140 x 19 Purlin 90 x 70 F7 Span 2700 Struts are Difficult to Estimate Develop a Best Guest Method Determine No Required 12500/2700 = 4.6 = 5 = 6 Each Side

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**Estimating Gable Roof - Struts**

Pitch = 24⁰ Overhang 450 Rafter 90 x 45 F7 600 c to c Tiled Roof with Flush Gable & Raking Eaves Ridge 140 x 19 Purlin 90 x 70 F7 Span 2700 Struts are Difficult to Estimate Develop a Best Guest Method Half Rise x √2 x √2 Tan 24⁰ x 3441 x 2 = 3064 Determine No Required 12500/2700 = 4.6 = 5 = 6 Each Side

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Estimating Sheet

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**Estimating Gable Roof – Collar Ties**

Pitch = 24⁰ Overhang 450 Rafter 90 x 45 F7 600 c to c Tiled Roof with Flush Gable & Raking Eaves Ridge 140 x 19 Purlin 90 x 70 F7 Span 2700 Collar Ties 90 x 35 Collar Ties on Every 2nd Rafter On top of Purlins 22/2 = HALF SPAN 3450

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Estimating Sheet

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**Estimating Gable Roof – Verge Trims**

Pitch = 24⁰ Overhang 450 Rafter 90 x 45 F7 600 c to c Tiled Roof with Flush Gable & Raking Eaves Ridge 140 x 19 Purlin 90 x 70 F7 Span 2700 Collar Ties 90 x 35 True Length of Rafter

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Rafter True length / 600 = 6.28 = 7 (Ridge Closes) = 33.6 Say 33.9

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Estimating Sheet

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**One Row of Purlin Each Side**

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Gable Roof Common Rafter

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**Top Plate Part of the Wall Frame Takes structural load from Roof**

Size must be determined from span tables

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Top Plate

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Exercise 1 Determine Required Top Plate Size

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**Common Rafter Principles**

Birdsmouth Max 1/3 Depth of Rafter

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