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

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

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 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 RidgeBoards

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

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

18. Struts Transfer Loads to Load Bearing Walls

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

24. Collar Ties

25. Common Rafter Principles Birdsmouth Max 1/3 Depth of Rafter

26. Common Rafter Principles Span – From Birdsmouth to Birdsmouth Half Span – From Birdsmouth to Centre

27. Common Rafter Principles True Rise – Birdsmouth/Top of Rafter to Apex NOTE – True Rise is not measured from TOP PLATE

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

29. Common Rafter Principles Pitching Line x-y line

30. Common Rafter Principles Measured to edge of Ridge Measured to centre of Ridge

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

32. Determine Rafter Length Mathematically Rafter 90 x 45 Ridge 125 x 19 Determine Span = 2700mm Determine Half Span = 2700/2 = 1350mm Determine Rafter Run= 1350- Half Ridge Thickness= 19/2 = 9.5 Rafter Run= 1341.5 True Length Rafter = 1341.5 / Cos 25 = 1480

33. Overhang Plan always from external wall

34. 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

35. Rafter 90 x 45 Ridge 125 x 19 In this case Brick Veneer Wall O/H = 450 + 40 + 110 cos 25 = 662mm Determine Rafter Length Mathematically Total Rafter Length Timber Frame = 1480 + 497 = 1977mm Brick Veneer = 1480 + 662 = 2142mm

36. 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

37. 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

38. 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

39. 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

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

41. Using Similar Triangles 1341/500 = 2.682 or = 2 r 341 Select Start Point Allowing for O/H Step out 2 full triangles

42. Intersection of Top of Rafter & Edge of Square

43. Using Similar Triangles 1341/500 = 2.682 or = 2 r 341 Select Start Point Allowing for O/H Step out 2 full triangles Step out 341 & use square to extend

44. Determine Roofing Angles used in Gable Roofs Plumb Cut Foot Cut

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

46. Determining Angles with Roofing Square Plumb Cut Foot Cut

47. Determining Angles Mathematically 1.Extend Line 90⁰ From Rafter

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

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

50. 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

51. 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

52. Complete Q5 in Workbook

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

54. Determine Roof Angles Graphically Extend Top Plate & Ridge

55. Determine Roof Angles Graphically Extend Top Plate & Ridge Mark Rise

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