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Gable Roof BCGCA3007B. Gable Roof Flush with no eaves Flush with raked eaves Boxed.

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Presentation on theme: "Gable Roof BCGCA3007B. Gable Roof Flush with no eaves Flush with raked eaves Boxed."— Presentation transcript:

1 Gable Roof BCGCA3007B

2 Gable Roof Flush with no eaves Flush with raked eaves Boxed

3 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

4 Flush Gable with Raked Eaves Roof Extends to Form eave Ridge Extends to Form Eave Verge Trimmers to Support Gable Rafter Second Rafter to Support Verge Trims Trimmers to Support Verge Trims and Roof Battens Gable Stud supports 1.Second Rafter 2.Brick Work or Wall Lining Top Plate may be extended to support Rafter

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

6 Verges Is the Junction of the Roof and the Barge/Verge Board Verge Detail for Tiled Roof

7 Verge Detail for Sheet Metal Roof

8 Principles of Roofing 1.Ridges are Level 2.Rafters run at 90 to wall plates 3.Hips & Valleys bisect all internal & external Corners 4.Roof members are set out along centerlines

9 Roofing Members Common Rafter Ridge Collar Tie Purlin Strut Ceiling Joist Top Plate Strutting Beam Hanging Beam

10 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)

11 Roofing Members Common Rafter Ridge Collar Tie Purlin Strut Ceiling Joist Top Plate Strutting Beam Hanging Beam

12 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

13 Joining Ridge Boards

14 Roofing Members Common Rafter Ridge Collar Tie Purlin Strut Ceiling Joist Top Plate Strutting Beam Hanging Beam

15 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

16

17 Roofing Members Common Rafter Ridge Collar Tie Purlin Strut Ceiling Joist Top Plate Strutting Beam Hanging Beam

18 Struts Transfer Loads From Purlins to Load Bearing Walls

19

20 Also Known as Barrap Straps

21

22

23 Roofing Members Common Rafter Ridge Collar Tie Purlin Strut Ceiling Joist Top Plate Strutting Beam Hanging Beam

24 Collar Ties

25 Gable Roof Common Rafter

26 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

27 Gable Roof Common Rafter Top Plate

28 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

29

30 Pitching Line

31 Starts at top corner of Top Plate Pitching Line

32 Starts at top corner of Top Plate Pitching Line

33 Starts at top corner of Top Plate Pitching Line Pitching line Runs Parallel to top of Rafter

34 Pitching Line Starts at top corner of Top Plate Pitching Line Pitching line Runs Parallel to top of Rafter This establishes the Pitch of the Roof

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

36 Common Rafter Principles Span – From Birdsmouth to Birdsmouth Half Span – From Birdsmouth to Centre

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

38 Common Rafter Principles If Rise is taken from Top Plate to Apex pitch will be incorrect

39 Common Rafter Principles Measured to edge of Ridge Measured to centre of Ridge

40 Confirmation of Learning Mark on Drawing in Workbook where, Centreline Length is measured to

41 Centreline Length Centre Line Length

42 Confirmation of Learning Centre Line Length Mark on Drawing in Workbook where, True Length is measured to

43 Common Rafter Principles True Length Centre Line Length True Length is usually what we need

44 Confirmation Of Learning Mark on Drawing in Workbook where, Rafter is measured from at Base

45 Measurement of Rafter Mark on Drawing in Workbook where, Rafter is measured from at Base Rafter is measured from this point

46 Confirmation Of Learning Mark on Drawing in Workbook where, The Rafter Length is measured

47 Measurement of Rafter Mark on Drawing in Workbook where, The Rafter Length is measured The Rafter Length is measure along the pitching line

48 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.

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

50 The “1 Metre Triangle”

51 Step 1 - Solve 1m Triangle 25° This is the a triangle based on the roof pitch Plan Length of 1 metre Rise per 1 metre of Plan Length Rafter Length per 1 metre of Plan length

52 Step 1 - Solve 1m Triangle 25° This is always no matter what the Roof Pitch is Plan Length of 1 metre Rise per 1 metre of Plan Length Rafter Length per 1 metre of Plan length

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

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

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

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

57 Step 1 - Solved 1m Triangle 25° Horizontal Travel = “Plan Length” For any roof of 25° the Rise per 1 m of Plan Length For any roof of 25° the Rafter Length per 1 m of Plan Length

58 Confirmation of Learning Determine the following 1 metre triangles 16°20° 30° 45°

59 Confirmation of Learning Determine the following 1 metre triangles 16°20° 30° 45°

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

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

62 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

63 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

64 Confirmation Of Learning What is the “Plan Length” of this Rafter?

65 Confirmation Of Learning What is the “Plan Length” of this Rafter? This is the plan length

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

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

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

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

70 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 25° The right hand triangle is 2x the size of the “1 meter triangle” 2x 65° 25°

71 Understanding the Principle Of Similar Triangles 25° This is our “1 meter” triangle 65° 25°

72 Understanding the Principle Of Similar Triangles 25° This is the TARGET triangle formed by the rafter 65° 25°

73 Understanding the Principle Of Similar Triangles 25° The first step is to determine proportional ratio between the triangles 65° 25°

74 Understanding the Principle Of Similar Triangles 25° The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths 65° 25°

75 Understanding the Principle Of Similar Triangles 25° 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 65° 25° 1 Metre Triangle Target Triangle

76 Understanding the Principle Of Similar Triangles 25° 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 65° 25°

77 Understanding the Principle Of Similar Triangles 25° 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 65° 25° We will call this the triangle multiplier

78 Understanding the Principle Of Similar Triangles 25° 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 65° 25° For the Common Rafter as we use the “1 meter” triangle, the Triangle Multiplier will always = Plan length of the Target triangle

79 Step 3 – Determine Rafter Length Centreline Length 25° 1 Rafter Length = Plan Length x Rafter Length per metre (RL/m) Rafter Length = 1350 x Rafter Length = ½ Span Plan Length 1489

80 Step 4 – Determine Rise (If Required) Centreline Length 25° 1 Total Rise = Horizontal Travel x Rise per metre Total Rise = 1350 x Total Rise = (1/2 Span) Plan Length

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

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

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

84 Step 2 – Determine Plan Length True Length 25° Plan Length “Plan Length” = ½ Span – ½ Ridge Thickness = 1350 – 9.5 = 1341 Determine how far the rafter travels HORIZONTALLY PLAN LENGTH Ridge 125 x 19

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

86 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 25° The right hand triangle is 2x the size of the “1 meter triangle” 2x 65° 25°

87 Understanding the Principle Of Similar Triangles 25° This is our “1 meter” triangle 65° 25°

88 Understanding the Principle Of Similar Triangles 25° This is the TARGET triangle formed by the rafter 65° 25°

89 Understanding the Principle Of Similar Triangles 25° The first step is to determine proportional ratio between the triangles 65° 25°

90 Understanding the Principle Of Similar Triangles 25° The first step is to determine proportional ratio between the triangles To determine this we ALWAYS determine using the PLAN lengths 65° 25°

91 Understanding the Principle Of Similar Triangles 25° 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 65° 25° 1 Metre Triangle Target Triangle

92 Understanding the Principle Of Similar Triangles 25° 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 65° 25°

93 Understanding the Principle Of Similar Triangles 25° 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 65° 25° We will call this the triangle multiplier

94 Understanding the Principle Of Similar Triangles 25° 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 65° 25° For the Common Rafter as we use the “1 meter” triangle, the Triangle Multiplier will always = Plan length of the Target triangle

95 Step 3 – Determine Rafter Length True Length 25° 1 Rafter Length = Plan Length x Rafter Length per metre (RL/m) Rafter Length = 1341 x Rafter Length = Plan Length 1479

96 Step 4 – Determine Rise (If Required) Centreline Length 25° 1 Total Rise = Horizontal Travel x Rise per metre Total Rise = 1341 x Total Rise = Plan Length

97 Overhang on a Plan is always measured from external wall

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

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

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

101 Rafter 90 x 45 Ridge 125 x 19 Determine Rafter Length Graphically 1.Draw Roof Full-size 2.Measure members directly 3.Avoid using scaled drawing 4.Scale use only for angles

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

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

104 Rafter 90 x 45 Ridge 125 x 19 Determine Rafter Length Graphically 1.Draw Roof Full-size 2.Measure members directly 3.Avoid using scaled drawing 4.Scale use only for angles

105 Determine Rafter Length Using Roofing Square Use Calculator 1.Press Tan 25 – what does this give you 2.Therefore for every 1 metre run there is 0.466m rise 3.Using the principle of similar triangles we half the size of the triangle

106 Use Calculator 1.Press Tan 25 – what does this give you 2.Therefore for every 1 metre run there is 0.466m rise 3.Using the principle of similar triangles we half the size of the triangle

107 Use Calculator 1.Press Tan 25 – what does this give you 2.Therefore for every 1 metre run there is 0.466m rise 3.Using the principle of similar triangles we half the size of the triangle

108 Using Similar Triangles 1341/500 = or = 2 r 341

109 Using Similar Triangles 1341/500 = or = 2 r 341 Select Start Point Allowing for O/H Step out 2 full triangles

110 Intersection of Top of Rafter & Edge of Square

111 Using Similar Triangles 1341/500 = or = 2 r 341 Select Start Point Allowing for O/H Step out 2 full triangles Step out 341 & use square to extend

112 Determine Roofing Angles used in Gable Roofs Plumb Cut Foot Cut

113 Determining Angles with Roofing Square When we set out rafter previously we determined plumb cut

114 Determining Angles with Roofing Square Plumb Cut Foot Cut

115 Determining Angles Mathematically 1.Extend Line 90⁰ From Rafter

116 Determining Angles Mathematically 1.Extend Line 90⁰ From Rafter 2.Extend Plumb Line

117 Determining Angles Mathematically 1.Extend Line 90⁰ From Rafter 2.Extend Plumb Line 3.Angle Formed is same as roof pitch

118 Determining Angles Mathematically Roof Pitch Right Angled Triangle This angle must be 65 ⁰ 90 – 25 = 65 This angle must be 25 ⁰ 90 – 65 = 25

119 Determining Angles Mathematically 1.Extend Line 90⁰ From Rafter

120 Determining Angles Mathematically 1.Extend Line 90⁰ From Rafter 2.Extend Plumb Line from same origin at top of Rafter

121 Determining Angles Mathematically 1.Extend Line 90⁰ From Rafter 2.Extend Plumb Line from same origin at top of Rafter 3.Angle Formed is same as roof pitch

122 Determining Angles Mathematically 1.Extend Line 90⁰ From Rafter 2.Extend Plumb Line 3.Angle Formed is same as roof pitch 4.Offset = Tan (pitch) x width

123 Determining Angles Mathematically 1.Extend Line 90⁰ From Rafter 2.Extend Plumb Line 3.Angle Formed is same as roof pitch 4.Offset = Tan (25⁰) x 90 = 42

124 Determining Angles Mathematically Next we can Determine our Birdsmouth 1.Width across plumb cut = 90/ cos = 99 3.Therefore max Birdsmouth = 33 4.Distance from top plate to top of Rafter = 66

125 Complete Q5 in Workbook

126 Determine Roof Angles Graphically Plan – View We can only see rafter run

127 Determine Roof Angles Graphically Extend Top Plate & Ridge

128 Determine Roof Angles Graphically Extend Top Plate & Ridge Mark Rise

129 Determine Roof Angles Graphically Extend Top Plate & Ridge Mark Rise Draw Hypotenuse Plumb Cut Foot Cut

130 Steps In Construction Gable Roof 1.Physically Confirm Span & Plates are Parallel 2.Calculate True Rafter, Rise & Plumb cuts 3.Mark out ceiling joists, rafters & ridge 4.Install Ceiling Joists 5.Cut Pattern Rafter & test to confirm 6.Cut required rafters & install

131 Estimating Gable Roof - Rafter From Previous Ceiling Estimate Determine No of Ceiling Joists12 250/ 600 = = = Pitch = 25⁰ Therefore 22 set of Rafters = Verge = 48

132 Determine Rafter Length Span = 6900 Pitch 24°

133 Determine Rafter Length Span = 6900 Pitch 24° 1

134 Determine Rafter Length Span = 6900 Pitch 24°

135 Determine Rafter Length Span = 6900 Pitch 24° Rafter =√ ( )

136 Determine Rafter Length Span = 6900 Pitch 24° Rafter =√ ( ) =

137 Determine Rafter Length Span = 6900 Pitch 24° 1 Rafter =

138 Determine Rafter Length Span = 6900 Pitch 24° 1 Rafter =1 ÷ Cos 24° 1.095

139 Determine Rafter Length Span = 6900 Pitch 24° 1 Rafter =1 ÷ Cos 24° =

140 Determine Rafter Length Span = 6900 Half Span = 3450

141 Determine Rafter Length Span = 6900 Half Span = 3450 Run = 3450 – 9.5 (Half Ridge) =

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

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

144 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

145 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

146 Estimating Sheet

147 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

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

149 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) =

150 Estimating Sheet

151 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 = Boxed eaves will require O/H ridge = 13400mm

152 Estimating Sheet

153 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

154

155 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

156 Estimating Sheet

157 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 2 nd Rafter On top of Purlins 22/2 = HALF SPAN 3450

158 Estimating Sheet

159 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

160 Rafter True length / 600 = 6.28 = 7 (Ridge Closes) 1200 = 33.6 Say 33.9

161 Estimating Sheet

162 One Row of Purlin Each Side

163 Gable Roof Common Rafter

164 Top Plate Part of the Wall Frame Takes structural load from Roof Size must be determined from span tables

165 Top Plate

166 Exercise 1 Determine Required Top Plate Size

167 Common Rafter Principles Birdsmouth Max 1/3 Depth of Rafter


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