BC CARPENTER APPRENTICESHIP PROGRAM

Transcription

1 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 COMPETENCY H-5 COMPETENCY H-5: Build Hip Roofs

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3 Acknowledgements and Copyright Permission Copyright 2015 Industry Training Authority This publication may not be reproduced in any form without permission by the Industry Training Authority. The Industry Training Authority of British Columbia would like to acknowledge the Carpentry Articulation Committee and Open School BC, a division of the BC Ministry of Education, as well as the following individuals and organizations for their contributions in updating the BC Carpenter Apprenticeship Learning Guides: Carpentry Articulation Curriculum Committee members Dennis Carlson, Tom Haag, Erik Hardin, Alf Leimert, Geoff Murray, Don Naidesh, Stephen Pelley, Al van Akker Writers: Gary Backlund, Geoff Murray Reviewers: Roy Mironuck, Geoff Murray, Stephen Pelley Open School BC Christina Teskey, project manager Dennis Evans, production technician, photographer, graphics, art coordination Brian Glover, production technician Shannon Sangster, copyright management Christine Ramkeesoon, art coordination Max Licht, artist Greg Aleknevicus, editor Keith Learmonth, editor Queen s Printer Contact Director, Crown Publications, Queen s Printer at Image Acknowledgments Cover image licensed from Thinkstock. Every effort has been made to secure copyright permission for the images used in this document. These materials contain information that has been derived from information originally made available by the Province of British Columbia at: and this information is being used in accordance with the Queen s Printer License British Columbia available at: ca/standards/2014/qp-license_1.0.html. They have not, however, been produced in affiliation with, or with the endorsement of, the Province of British Columbia and THESE MATERIALS ARE NOT AN OFFICIAL VERSION. ISBN: Please note that it is always the responsibility of any person using these materials to inform him/herself about the Occupational Health and Safety Regulation pertaining to his/her work. The references to WorkSafeBC safety regulations contained within these materials do not / may not reflect the most recent Occupational Health and Safety Regulation (the current Standards and Regulation in BC can be obtained on the following website: We want your feedback! Please go to the BC Trades Modules website ( to enter comments about specific sections that require correction or modification. All submissions will be reviewed and considered for inclusion in the next revision. Ordering Crown Publications, Queen s Printer PO Box 9452 Stn Prov Govt 563 Superior St. 2nd Flr Victoria, B.C. V8W 9V7 Phone: Fax: crownpub@gov.bc.ca Web: Version 1, July 2015

4 COMPETENCY H-5 Build Hip Roofs Contents Learning Task 1: Hip Roof Components Self Test Learning Task 2: Calculate and Lay Out Hip Rafters Self Test Learning Task 3: Lay Out Hip Jack Rafters Self Test Learning Task 4: Build a Hip Roof Self Test Learning Task 5: Lay Out Cuts for Roof Sheathing Self Test Learning Task 6: Calculate Quantities of Ceiling and Roof Framing Materials Self Test Answer Key BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

5 COMPETENCY H-5 Build Hip Roofs Roof construction is a major part of wood-frame construction. Whether the roof is a truss roof or a rafter-framed roof, knowledge of roof framing is a vital skill for carpenters. Objectives When you have completed the Learning Tasks in this Competency, you will be able to: name the components of a hip roof use rafter tables to calculate the length of hip rafters and jack rafters determine the adjustment for hip and jack rafters lay out a hip rafter lay out a jack rafter assemble a hip roof lay out sheathing cuts erect hip roof trusses Competencies Written: Build Hip Roofs You will be tested on your knowledge of hip roof terminology, layout methods, adjustments, calculations, and the use of rafter tables and framing squares. Practical: You will be required to calculate, lay out, cut, and erect a hip roof. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 5

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7 Learning Task 1 Competency H-5 LEARNING TASK 1 Hip Roof Components Specific terms are used to describe the components used in hip roof framing. Hip Roof Framing Terms A roof with hips at both ends is referred to as a cottage-style roof. The hip rafter extends from the corner of the building to the ridge. In plan view, on an equal slope roof, it runs at 45 to the ridge and plate. Jack rafters are common rafters that are cut to meet the hip rafter. The jack rafter extends from the wall plate to the hip. The end common rafter is a common rafter that extends from the plate to the ridge on the hip end of a building and is supported at the top by the end of the ridge (Figures 1 and 2). The theory length of an end common rafter is the same as the theory length of a common rafter. Hip rafter Ridge Jack rafter Common rafter Wall plate Hip rafter End common rafter Figure 1 Hip roof terms BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 7

8 Learning Task 1 Competency H-5 Jack rafters Common rafters End common rafter Hip rafter Figure 2 Plan view of a hip roof Cheek cuts are angled cuts used to fit hip and jack rafters to other rafters. The hip usually has a double cheek cut and the jack a single cheek cut. There are opposing right and left hand single cheek cuts (Figure 3). On an equal slope roof, these cuts are made with the circular saw set to 45. Single cheek cut Double cheek cut Figure 3 Single and double cheek cuts Working points are created by the intersections of the theory lines of the rafters. Often the working point for one rafter is the working point for other rafters. The working point is located at the centre line of the rafter. 8 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

9 Learning Task 1 Competency H-5 The tripod method (also called the tripod connection ) is the typical way of connecting the commons, the hips, and ridge (Figure 4). The two commons and the end common form the three-legged tripod. Half the thickness of the ridge End common Working point Half the thickness of the common Figure 4 Tripod connection showing adjustments for commons and ridge Now complete Self Test 1 and check your answers. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 9

10 Learning Task 1 Competency H-5 Self Test 1 1. Identify the rafters shown in Figure 1. c. e. a. d. b. f. g. Figure 1 a. b. c. d. e. f. g. 2. What type of cheek cut is used for a hip rafter? 3. What type of cheek cut is used for a jack rafter? 4. Sketch the plan view of the connection of the ridge, common, end common, and hip rafters using the tripod method. Only show one end of the ridge and draw the rafters full size. Use a ¾" thick ridge and use 1½" thick common, end common, and hip rafters. The hip rafter fits into the common and end common at a 45 angle. 10 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

11 Learning Task 2 Competency H-5 LEARNING TASK 2 Calculate and Lay Out Hip Rafters A gable roof consists of two sloped surfaces meeting at the ridge. A hip roof has a sloping surface at each end of the roof that meets the two slopes at the sides of the roof. Figure 1 Hip roof (isometric view) The hip rafter supports the joint between the roof slopes. On an equal slope roof, the slope on the end surface is the same as the slope of the side surfaces. (e.g., if the common rafters have a slope of 8 in 12, the end common rafters have an 8 in 12 slope as well.) In plan view, the hip rafter forms an angle of 45 to the outside walls. 45º Figure 2 The angle formed by the hip when seen in plan view Drawing Rafters in Plan View The rafter locations are often not shown on blueprints it s the carpenter s role to make a roof plan. To draw the plan view location of a hip rafter on a rectangular building, draw a line from the corner of the building toward the centre of the building at exactly 45 to the outside wall. Use a set square to lay out this angle. Draw the other hips toward the centre as well. Where these lines meet is the location of the tripod and the end of the ridge (Figure 4). BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 11

12 Learning Task 2 Competency H-5 Even the most complicated intersecting roof can be drawn using this simple principle. 45 Right-angle Triangle A 45 right-angle triangle is a special triangle formed by drawing a diagonal across a square (Figure 3) º 12 Figure 3 45 right-angle triangle Compare the right angle triangle in Figure 3 to the plan of the hip roof in Figure 4. Notice that the run of the common rafter is the same as the distance from the end of the roof to the tripod point, which is the run of the end common. Tripod point Run Run Run Span Run Figure 4 Location of the tripod point Ridge Theory Length The theory length of the ridge for a hip roof is equal to the length of the building minus the run of both end commons. This is the same as the length of the building minus the span of the building. In Figure 10, the theory length of the ridge is 30' (2 10') = 10' 12 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

13 Learning Task 2 Competency H-5 Ridge Adjustments The working point for the ridge is at the centre line of the common rafters at the tripod. The actual length of the ridge is the theory length plus the thickness of the common rafter (half the thickness at each end). Plus half the thickness of the common at each end Working point Figure 5 Adjustment to the ridge board for a hip roof End Common Rafter The line length and layout of the end common rafter are the same as a common rafter except for the adjustment at the ridge. For an end common, the adjustment is minus ½ the thickness of the common. For a common rafter, the adjustment at the ridge is minus ½ the thickness of the ridge. Working point End common ½ the thickness of the ridge ½ the thickness of the common Figure 6 The end common rafter adjustment at the ridge BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 13

14 Learning Task 2 Competency H-5 Hip Rafter The hip rafter rises to the same height as the common rafter, but the hip runs over a longer horizontal distance. The hip has a flatter slope than the common. For a roof with a slope of 8 in 12, both the hip and common rafters rise 8" at 12" square from the outside corner of the building (Figure 7). Hip slope Wall line Wall line Figure 7 Slope of the hip rafter Plumb Cuts on Hip Rafters In Figure 3, where the sides of the square are 12", the hypotenuse is 16.97". This is how far the hip runs when the common runs 12". In metric, if the sides of the square are 250 mm, the hypotenuse is mm. (Remember that run is horizontal, so the 16.97" and mm lengths are horizontal dimensions in plan and section views.) When laying out a plumb cut on the hip rafter, use 17" as the unit of run (Figure 8). (If using metric, use 354 mm as the unit of run.) 8" 12" 8" 17" Common Hip or valley Figure 8 Plumb cuts on rafters 14 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

15 1 2 3 Learning Task 2 Competency H-5 Mark on the unit of rise side of the square to lay out the plumb cut and on the unit of run to lay out the level cut. Line Length of the Hip Rafter The triangle formed by the run of the common and the run of the hip is the basis for calculating the theory length of the hip rafter. For each unit of run in the common rafter, there is a unit of run in the hip rafter. Only the size of the unit is larger. The run of the hip does not usually need to be calculated simply use the same number of units of run as the common. The line length of the hip is found by multiplying the number of units of run by the Length of the Hip Per Unit Run (LHPUR). The LHPUR is given on the second row of the rafter table on a framing square (Figure 9) COMMON RAFTER LENGTH PER FOOT OF RUN HIP OR VALLEY RAFTER LENGTH DIFF IN LE NGTH OF J ACK S 16 INCH CE NTR E S DIFF IN LE NGTH OF J ACK S 24 INCH CE NTR E S SIDE CUT OF JACKS SIDE CUT OF HIP OR VALLEY /8 43 1/4 6 11/16 8 1/ /4 24 5/ / /16 1 Figure 9 Rafter table on the framing square The dimensions given on the framing square can also be calculated: 2 2 The LCPUR for an 8 in 12 slope roof is ( )= " 2 2 The LHPUR is ( )= " On a metric roof with a slope triangle of 200 mm in 250 mm: 2 2 LCPUR = ( )= mm 2 2 LHPUR = ( )= mm The line length for a hip rafter is found by multiplying the number of units of run in the common by the LHPUR. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 15

16 Learning Task 2 Competency H-5 Example 20' 2' Typ 2' 30' Figure 10 Imperial hip roof rafter layout The building in Figure 10 is 20 feet wide with an 8 in 12 slope. The calculation for the line length of the hip rafter is as follows: 20'/2 = 10' (run of the common rafter) 10'/1 = 10 units of run " = 187.6" Line length of the hip = 187 5/8" Hip Overhang The hip projection has the same number of units of run as the common projection. If the projection is 24" (2 units of run), and the roof slope is 8 in 12, the hip overhang is equal to: " = 37.52" Hip overhang = 37 ½" 16 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

17 Learning Task 2 Competency H-5 Hip Rafter Layout The hip rafter is laid out in four steps: 1. lay out the three working points and plumb lines 2. make adjustments at the ridge 3. lay out the bird s mouth 4. make adjustments at the tail Working Points and Plumb Lines The layout of the working points is similar for a hip rafter as a common. The plumb lines are also laid out in the same manner as for the common, except that a unit rise of 17" (354 mm with a 250 mm unit of run at the common) are used on the framing square as the unit run. Adjustments at the Ridge The hip rafter connects into the intersection of the end common and the common rafters (the tripod ). The line length of the hip is measured from the working point, which is at the centre of the ridge. The hip must be shortened by ½ the diagonal thickness of the common rafter. Hip Working point End common ½ the thickness of the ridge Figure 11 Shortenings at the ridge ½ the thickness of the common If the common rafter is 1 ½" thick (38 mm), the full diagonal is 2 1/8" (54 mm) and half is 1 1/16" (27 mm). The diagonal measurement can be calculated, but it s easier and more accurate to lay out a 45 line across the actual rafter and measure the diagonal. (It s more accurate because if the rafter is slightly more BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 17

18 Learning Task 2 Competency H-5 or less than 1 ½", the difference in thickness will be reflected in the diagonal measurement.) This technique is especially important when using custom size or timber frame lumber, or anything other than typical 2 dimension lumber. Figure 11 is a plan view. The measurement for ½ the diagonal of a common rafter is therefore measured on the level. When measuring any adjustment to a rafter, the adjustment is measured on the level or, in other words, square to the plumb cut " Working point 4" 17" Figure 12 Adjusting for the thickness of the common rafters The 1 1/16" distance is used for any slope of roof framed with 1½" stock because it s measured square to the plumb cut. Double Cheek Cut After laying out the adjustment for the thickness of the common, the hip is cut with a double cheek cut at the shortened point. The layout of single and double cheek cuts is the same for any situation needing these cuts. The layout is made by measuring ½ of the thickness of the rafter being cut in each direction from the line that locates the point of the double cheek cut. This is the solid line 1 1/16" from the working point in Figure 13. The dashed lines are the cut lines. Working point " ¾" 2 6 hip rafter Figure 13 Layout of a double cheek cut Saw Directions The saw is set at an angle of 45 when making cheek cuts. 18 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

19 Learning Task 2 Competency H-5 The double cheek cut is laid out on the face of the rafter. Both cheeks are cut from the one face. Set the saw to 45. The first cut is made down the line closest to the working point (W.P.). This leaves the layout mark for the second cut, which is made up the second layout line. Remember to keep the saw on the waste side of the layout for both cuts (Figure 14). First cut Second cut Keep both cuts in the waste wood After the first cut After the second cut Figure 14 Direction of cutting for double cheek cuts Bird s Mouth The bird s mouth of the hip rafter requires a tricky layout. Looking at a plan view drawing of the hip at the corner of the plates (Figure 16), notice that the hip must be cut at the working point line for the rafter to clear the corner of the building. To align the tops of the rafters (to ensure the sheathing lays flat), the wood above plate (WAP) for the hip must be the same as the common rafter. This cut must be made at the point where these plumb WAP lines line up at the edge of the plate. For the hip rafter, the side of the hip crosses the plate ½ the thickness of the hip towards the ridge from the working point line. Using 1½" (38 mm) thick dimension lumber, this is ¾" (19 mm) up the hip, towards the ridge. Building line ½ the thickness of the hip W.P. W.P. Point where the hip meets the building line Figure 15 Point where the hip meets the building line BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 19

20 Learning Task 2 Competency H-5 The WAP at the bird s mouth of the common sets the WAP at the bird s mouth for a hip rafter. Hip jacks also have the same WAP as the commons. Hip rafter Hip jack rafter 3" 3" W.A.P. Figure 16 Depth of the bird s mouth Measure half the thickness of the hip towards the ridge from the working point. As with other adjustment measurements, make the measurement square to the plumb cut. Then measure down this new line the same WAP as that was used on the common (Figure 17). Half of the thickness of the hip Working point Wood above plate Figure 17 Bird s mouth on the hip rafter Cut the bird s mouth through to the working point. The bird s mouth will always look large on hip rafters. This is due to the lower slope of the hip and because the hip rafter is at least one nominal size larger than the common. Adjustments at the Tail If the projection is measured to the outside of a rough fascia, the thickness of the fascia board will have to be cut away from the end of the hip rafter overhang. The adjustment is the full diagonal of the rough fascia. 20 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

21 Learning Task 2 Competency H-5 Projection Building line Full diagonal thickness of the rough fascia Outside of rough fascia Working point Figure 18 Plan view of rough fascia The full diagonal of a 1½" thick rough fascia is 2 1/8". Measure 2 1/8" from the working point towards the ridge square to the plumb cut. ¾" Working point 2 6 valley rafter 2 1 8" Figure 19 Adjusting for the rough fascia The layout of the double cheek cut at the end of the tail of the hip is identical to the cut at the ridge. An alternate method to calculate and lay out the overhang of the hip rafter is to subtract the thickness of the fascia when determining the number of units of run. Using the example of an 8 in 12 slope roof with a 24" projection, subtract 1½" from 24" to get 22½". 22.5" 12 = units of run " = " = 35 3/8" BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 21

22 Learning Task 2 Competency H-5 Measure down from the working point at the bird s mouth 35 3/8" and lay out the double cheek cuts from this mark. The adjustment for the thickness of the fascia was made in the calculations, not the layout. Template Layout To build a cottage-style roof, four identical hip rafters are needed. The first hip is laid out and used as a template for the others. Double-check the measurements and adjustments used for the first hip. When using a common rafter as a template, the shape of the rafter is cut out. When using a hip as a template, do not cut out the hip. Cutting out the hip will remove some of the layout lines needed to mark the other rafters. Align the template to the next hip to be cut and transfer the marks with the framing square Figure 20 Using a hip template Calculation Example for an Imperial Dimension Hip Roof The following spreadsheets are useful for organizing the calculation and layout of rafters on multi-sloped roofs. Using the example of Figure 10, for a building built with SPF #1 lumber, in Kamloops, start by determining the size of the common rafter using the Building Code. With a span of 20 feet, the run of the common rafter is 10 feet = m. (Remember, the BCBC uses the term span for the run of the common.) Kamloops has snow load rating of 1.8, which is rounded to 2 for use in Span Table A-6 (Figure 21). Given the rafter spacing of 24" o.c. (600 mm), 2 6 commons and 2 8 hips can be used. A 1 8 ridge will be used. 22 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

23 Learning Task 2 Competency H-5 Name Run # Units Length/unit of run Theory length Common rafter 10' /16" Common overhang 2' /16" Ridge 30' (2 x 10') = 10' 120" Hip n/a /8" Hip overhang n/a ½" Common overhang (alt) Hip overhang (alt) 1' 10 ½" Adjustments Amount Cut ½ thickness of ridge 3/8 Square plumb full thickness of subfascia 1 ½" ½ thickness of common at each end = 1½" half diagonal of common 1 1/16" Double cheek full diagonal of fascia 2 1/8" Double cheek /16" n/a Double cheek n/a /16" n/a Double cheek End common /16" ½ thickness of common ¾" Common difference in jack rafters 16" " Longest jack " = = 123" ½ diagonal of hip 1 1/16" Single cheek 3rd jack ( ) = = 849/16" Single cheek Fascia 30' + (2 2')= 34"; 20' +(2 2') = 24'; 2 ( ) =116' Figure 21 imperial hip roof rafter length spreadsheet 20' 2' Typ 2' 30' Figure 22 Imperial hip roof (copy of Figure 10) BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 23

24 Learning Task 2 Competency H-5 Calculation Example for a Metric Dimension Hip Roof Using the example shown in Figure 22, for a 200 in 250 slope roof, built with SPF #1 lumber, in Kamloops, start by determining the size of the common rafter using the Building Code. With a span of 7.2 m, the run of the common rafter is 3.6 m. (Remember, the BCBC uses the term span for the run of the common.) Typ Typ Figure 23 Metric roof plan Kamloops has snow load rating of 1.8, which is rounded to 2 for use in Span Table A-6 (Figure 23). Given the rafter spacing of 600 mm o.c., commons and hips can be used. A ridge will be used. 24 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

25 Learning Task 2 Competency H-5 Name Run # Units Length/unit of run Theory length Common rafter Common overhang Adjustments Amount Cut ½ thickness of ridge 10 Plumb full sub fascia 38 Plumb Ridge = 3 m 3000 Hip n/a Hip overhang n/a Common overhang (alt) Hip overhang (alt) +½ thickness of common at each end = 38 Square ½ diagonal thickness of 27 Double cheek common full diagonal thickness of fascia 54 Double cheek n/a n/a Plumb n/a n/a n/a Double cheek End common Common difference in jacks Longest jack rafter = 3842 ½ thickness of common ½ diagonal thickness of hip 19 Plumb 27 Single cheek 3rd jack 4610 (3 768) = 2306 Single cheek Fascia (2 0.6) = 11.4; (2 0.6) = 8.8; 2 ( ) = 40.4 m Figure 24 Metric hip roof rafter length spreadsheet Now complete Self Test 2 and check your answers. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 25

26 Learning Task 2 Competency H-5 Self Test 2 1. What figures on the framing square are used to lay out the plumb cut on a hip rafter? 2. What figures on the framing square are used to lay out the seat cut at the bird s mouth for a hip rafter? 3. Calculate the line length of a hip rafter for a building that s 28' wide with a 5 in 12 slope. (Use Figure 1.) / / / /8 25 5/ / / /2 24 3/4 11 5/ /16 Figure 1 Portion of the rafter table 4. Calculate the overhang length for a hip rafter if the projection is 450 mm and the roof slope is 175 in BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

27 Learning Task 2 Competency H-5 5. Draw a sketch showing the layout of the hip. Show in detail, including measurements, the adjustments and cut lines. Use a roof slope of 5 in 12, a 1 8 ridge board, 2 4 common rafter, and 2 6 hip rafter. 6. On a metric roof, using an 18' board to include the overhang, what is the offcut of the 4th jack rafter? 7. Where can the off-cut from question 6 be used? BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 27

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29 1 2 3 Learning Task 3 Competency H-5 LEARNING TASK 3 Lay Out Hip Jack Rafters Hip jack rafters are common rafters that are cut to meet the hip. The lengths and layout for hip jacks are based on a common rafter in that the slope, bird s mouth, and overhang are the same as for the common. Jack rafters Figure 1 Jack rafters on a hip roof Common Difference in Line Lengths of Jack Rafters The line length of the longest hip jack rafter is found by subtracting the difference in length of the jacks from the line length of the common rafter. The difference in length of jacks is found on the third and fourth rows of the rafter table on a framing square (Figure 2). This dimension is also referred to as the common difference COMMON RAFTER LENGTH PER FOOT OF RUN HIP OR VALLEY RAFTER LENGTH DIFF IN LE NGTH OF J ACK S 16 INCH CE NTR E S DIFF IN LE NGTH OF J ACK S 24 INCH CE NTR E S SIDE CUT OF JACKS SIDE CUT OF HIP OR VALLEY /8 43 1/4 6 11/16 8 1/ /4 24 5/ / /16 1 Figure 2 Rafter table BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 29

30 Learning Task 3 Competency H-5 The common difference in jacks can be taken from the rafter table (Figure 3). This dimension is how much shorter (or longer) one rafter will be from the next. The longest hip jack is spaced off the common by the on centre spacing. A spacing of 24" o.c. means a greater common difference than an o.c. spacing of 16". Diff in length of Jacks 16" centres Diff in length of Jacks 24" centres / / / /8 25 5/ / / /2 24 3/4 11 5/ /16 Figure 3 Portion of the rafter table The difference in length of jacks for a 4 in 12 slope with jacks at 16" o.c. is 16 7/8". To get the line length of the longest jack, subtract 16 7/8" from the line length of the common rafter. Subtract 16 7/8" from this length to get the line length of the 2nd longest jack, and so on. (Off-cuts from the longer jacks can often be used as the shorter jacks.) Difference in length of jacks " 12 4 W.P. W.P. The bird s mouth and the overhang of the hip jack are identical to the common Figure 4 First hip jack W.P. is measured from the common rafter W.P. 30 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

31 Learning Task 3 Competency H-5 Because the single cheek cut on the jack is laid out differently than the ridge cut of the common, the difference is measured from the working point of the common rafter, not the cut line. The common difference is the difference in length along the slope of the rafters. The numbers on the framing square are calculated as follows. Given an o.c. spacing of 16" and a slope of 5 in 12 (with a LCPUR of 13"), the common difference is: (13 12) 16 = = 17 5/16" Notice that the common difference for jacks spaced 24" o.c. (the fourth line on the rafter table) is twice the LCPUR (the first line on the rafter table). Similarly in metric, with a roof slope of 125 in 250, with rafters spaced at 400 mm o.c., the LCPUR is and the common difference is: ( ) 400 = 447 mm Hip Jack Adjustments and Cheek Cut Once the line length is measured and the adjustments and the cheek cut are laid out on the first hip jack, the second hip jack is measured from the actual cut line. Because the adjustments are the same for each jack rafter, the common difference can be subtracted from the cut line. This way the single cheek cut for each rafter does not need to be laid out. In plan view, the hip jack rafter fits into the hip rafter at a 45 angle. The adjustment for the jack rafter is half of the diagonal thickness of the hip. Half of the diagonal thickness of the hip rafter (1 1 16" for a 2 6 hip) W.P. Hip jack Hip Figure 5 Plan view of adjustment for the hip jack BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 31

32 Learning Task 3 Competency H-5 The adjustment from the working point is measured towards the tail of the jack. Measure the adjustment square to the plumb cut (Figure 6). The layout of the cut line can be made in either direction, but it s easiest to cut on the long point. For a typical right-handed circular saw, this means the cut line layout is made up the rafter, towards the hip " W.P. Single cheek cut line ¾" Figure 6 Adjustment and cheek cut for a hip jack rafter Direction of Cut The cut lines are to the long point of the cut. Set the saw to 45 and cut downward along the cut line (Figure 7). On a typical right-handed circular saw, the base of the saw is supported by the rafter stock and the off-cut can fall away. W.P. Direction of cut (set the saw to a 45º angle) Cut line Figure 7 Direction of cut Pairs of Jacks Hip jack rafters are in pairs, one on either side of the hip. Both rafters in the pair are the same length and the layout will be the same except that the cheek cuts are on opposite sides (Figure 8). Jacks are best installed in pairs in order to keep the hip straight. 32 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

33 Learning Task 3 Competency H-5 A pair of hip jack rafters Figure 8 Pairs of hip jacks Subsequent Hip Jacks Since the single cheek cut layout is the same for each rafter, the second, third, and remaining hip jack rafters are laid out by measuring the difference in jacks from the cut line of the first hip jack (Figure 9). Careful layout and cutting will allow for the off-cuts from the longer jacks to be used as the shorter jacks. Difference in lengths of jacks 12 4 W.P. for the common rafter " " " " W.P. Cut line for the first hip jack Cut line for the second hip jack Cut line for the third hip jack Cut line for the fourth hip jack Figure 9 Layout for cutting subsequent hip jack rafters BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 33

34 Learning Task 3 Competency H-5 Efficient Use of the Template The layout shown in Figure 9 is a typical template for a cottage-style roof. The template is laid out and double-checked. It is then used to cut all of the common rafters. Next, the template is cut off at the end common layout and used to cut the two end commons. Then it is cut off at the first hip jack and used to lay out the four pairs of jacks at that length. The same is done with the second, third, and fourth pairs of hip jacks. Using the same template for all commons, end commons, and hip jacks ensures that the layout of the tail is exactly the same for all rafters. If the walls are straight before installing the rafters, the eave line will be straight after the rafters are installed. Another technique is to make a template for the bird s mouth and tail. Once the line length of the jack rafter is calculated, the measurement is made from the working point at the bird s mouth up to the top of the rafter. Now complete Self Test 3 and check your answers. 34 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

35 Learning Task 3 Competency H-5 Self Test / / / /8 25 5/ / / /2 24 3/4 11 5/ /16 Figure 1 Portion of rafter table 1. What is the difference in lengths of jacks for a 4 in 12 sloped roof if the jacks are at 24" o.c.? 2. What is the difference in lengths of jacks for a 3 in 12 sloped roof if the jacks are at 16" o.c.? 3. Draw a sketch showing the layout of a hip jack rafter. Use a 5 in 12 slope and a 1½" thick hip and hip jack rafter. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 35

36 Learning Task 3 Competency H-5 4. What is the common difference for hip jacks for an 8 in 12 slope roof spaced 16" o.c.? 5. What is the common difference for hip jacks for a 200 in 250 slope roof space 600 mm o.c.? 36 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

37 Learning Task 4 Competency H-5 LEARNING TASK 4 Build a Hip Roof After the ceiling joists are installed and the ridge and rafters are cut, the assembly of the hip roof can begin. Building the Tripods The tripod consists of an end common and two common rafters. The commons that form the tripod are set first and the ridge placed between them, similar to a gable roof. The end common is added next. This forms a stable structure that s braced in all directions. After the tripods are built, the rest of the common rafters are installed. It s good practice to place a string line along the ridge to ensure it stays straight. Installing the Hips The hip rafters are installed into the tripod. The top corners of the double cheek cuts of the hips should be flush with the top edges of the commons. (This will ensure the roof sheathing lies flat.) The centre of the hip will be slightly below the edges of the common rafters and the ridge. Sight across the roof to ensure the tops of the hip and commons have formed a flat surface. Installing the Hip Jacks The hip jacks are nailed to the sides of the ceiling joists and to the side of the hip. The top edge of the single cheek cut of the jack should be flush with the edge of the hip. (This will ensure the roof sheathing lies flat.) The pairs of hip jacks should meet and look symmetrical. Sight the hip for straightness as the jacks are installed. Installing the Rough Fascia Check the ends of the rafter tails (where the fascia will be fastened) for straightness. If there are irregularities, use a chalk line and trim the tails as needed. It s important that the tails be straight, as this is often a visible sightline when viewing the house from a distance. The eavestrough, fastened to the fascia, needs to be straight. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 37

38 Learning Task 4 Competency H-5 There are several ways to install the rough fascia. It must support the bottom edge of the roof sheathing. The rough fascia is installed so that its outer top edge is in line with the top of the rafter. Flush with rafter Figure 1 Installing the rough fascia The rough fascia can be also installed so that the outer edge of the sheathing is flush with the outside of the fascia and covered by the finished fascia. Figure 2 Finished fascia covering edge of sheathing Now complete Self Test 4 and check your answers. 38 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

39 Learning Task 4 Competency H-5 Self Test 4 1. Describe how the tripod is built. 2. What is done to ensure the roof sheathing lies flat where the hips are connected to the tripod? 3. What is done to ensure the roof sheathing lies flat where the hip jack connects to the hip? BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 39

40 40 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

41 Learning Task 5 Competency H-5 LEARNING TASK 5 Lay Out Cuts for Roof Sheathing Installing the Roof Sheathing Lumber or panel-type roof sheathing can be used for sheathing hip roofs. The installation is similar to the installation on gable roofs. Where the sheathing meets the hip, it s common practice to let the sheathing run wild and cut it off as the sheets are installed. Use a chalk line to mark the cut of the sheathing at the hip. Hook the chalk line on a nail at the working point at the top and pull to the corner of the fascia each time to ensure a consistent straight line. The saw angle is set by placing the base of a circular saw on a connection of a jack rafter and the hip. Figure 1 Setting a circular saw for plumb sheathing cuts Adjust the bevel angle so that the blade is plumb, touching the side of the hip. Make a test cut and check the angle. When working at heights of over 10 feet from the ground or the floor, fall protection is required. For roof framing, this can be either scaffolding, or lifelines and harnesses. Layout of Sheathing Cuts If lumber sheathing is used, the angle cuts on the boards can be laid out using a framing square. The figures used are the LCPUR, the unit run, and the unit BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 41

42 Learning Task 5 Competency H-5 rise. The edge cut defines the angle that the saw is set to, and the face cut defines the line to follow with the saw. Marking the Face Cuts The LCPUR and the unit of run are used to lay out the face cut. Mark the cut on the unit of run. Unit of run LCPUR Figure 2 Marking the face cut on lumber sheathing Marking the Edge Cuts The LCPUR and the unit of rise are used to lay out the edge cut. Mark the cut on the unit of rise (Figure 3). The square is held across the edge of the board. If the board is in place on the roof as shown in Figure 3, the square will not be in a plumb position. LCPUR Figure 3 Marking the edge cut 42 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

43 Learning Task 5 Competency H-5 An easier way to set the saw angle is to place the base of a circular saw on a connection of a jack rafter and the hip. The base of the saw is in the plane of the roof. Adjust the bevel angle so that the blade is plumb, touching the side of the hip. Make a test cut and check the angle. Panel-type Sheathing Cuts As mentioned above, it s common to cut the sheathing on the hip as you go. This can be a difficult and dangerous procedure. The off-cut needs to be supported so it doesn t fall off the roof. The cut at the bottom of the first row of sheathing is very exposed and far from the fall protection anchor. Sawdust on the roof makes it slippery. Combine these factors with the fact that you may be two or three stories up, on a windy day, and the task is not only difficult, it s dangerous. A cautious approach is required. It s not difficult to lay out the sheathing cut for the hip on a sheet of plywood. The long point will be at the bottom of the sheet. The short point will be at the top. To find the layout point for the short point, calculate the run for a line length of 48" (the width of a sheet of plywood). Example On an 8 in 12 roof, the LCPUR is = X 48 X = " = 39 15/16" Make a mark 39 15/16" from the top corner (that would run wild over the hip) and chalk a line down to the bottom corner. This is the cut line for the hip. Cut off the square end to the middle of the furthest rafter over. Now complete Self Test 5 and check your answers. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 43

44 Learning Task 5 Competency H-5 Self Test 5 1. How do you mark the line to cut the plywood over the hip? 2. What numbers do you use to lay out the face cut on lumber sheathing? 3. Calculate the offset for the short point of a sheathing cut over the hip on a roof with a slope of 200 to BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

45 Learning Task 6 Competency H-5 LEARNING TASK 6 Calculate Quantities of Ceiling and Roof Framing Materials A quantity survey of the material required for a hip roof is similar to that of a gable roof. Calculations are made based on the plan. On a simple building, numbers can simply be counted from the roof framing plan. The actual lengths of the framing members will be determined on-site. Calculated dimensions are used as a starting point for the estimate. Lumber is available in 2' increments, so some waste is normal. Rounding up to simplify calculations is common it s not always necessary to carry three decimal places. Determining waste factors is difficult and depends on the design of the building and experience of the builders. A hip roof will likely have more waste that a gable roof due to its more complex design and the angle cuts on rafters and sheathing. 20' 2' Typ 2' 30' Figure 1 Plan view of imperial hip roof The ceiling joists will be 20' long if they span the entire width. Depending on the floor plan, the ceiling joists will likely span to an interior bearing wall and lap with a joist spanning from the other side. For estimation purposes, assume a 1' overlap. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 45

46 Learning Task 6 Competency H-5 Stub joists run perpendicular to the width. Estimate stub joists at 4' long, spanning two joist spaces. Ceiling joists: 30' (2 4') = 22' 22' 24" o.c. spacing = 11 spaces + 1 to start = 12 per side 12 2 = 24 pieces at 12' Stub joists: 20' 2' = 10 spaces + 1 to start = 11 per end 11 2 = 22 pieces at 4' (11 pieces at 8') Ridge The ridge is 30' (2 10') = 10'. Because the ridge needs an adjustment at each end, its actual length is 10' 1½". (1 piece at 12'). Common rafters Common rafters are estimated as if the building were a gable end. This requires careful use of the off-cuts of longer jack rafters as shorter jack rafters. End commons need to be included. 30' 24" o.c. = 15 per side + 1 = 16 per side 2 sides = 32 pieces + 2 end commons = 34 commons The commons have a line length of = 144.2" which is just over 12'. When possible the overhang is the same piece of lumber, so = Total length of common including overhang = = " = ' (16-foot pieces). Hip rafters The roof requires four hip rafters. Total length, including overhang, is 187.6" " = ' = 18.76'. This requires 20-foot pieces which may not be available. Several alternatives are available. One is to use LVL material for the hip rafter which is available in long lengths. Another is to stop the hip rafter at the plate and lap a second piece to the side of the hip to create the overhang. Sheathing The area of the roof is 34' 24' ( ) = sq. ft. (The slope gain ratio is ) A sheet of plywood measures 32 square feet (4' 8'), so = sheets are needed. There will be some waste due to the hips. Including 5% waste will require 33 sheets. 46 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

47 Learning Task 6 Competency H-5 Fascia The fascia extends all the way around the building: 34' + 34' + 24' + 24' = 116'. The hip ends require two 12-foot pieces each. The long sides require three 12-foot pieces each. Fasteners Fasteners for sheathing include 2½" common nails, galvanized common nails, or staples. The Code minimum nailing pattern for sheathing is 150 mm o.c. along the edges and 300 mm o.c. on intermediate supports. Estimate an average of 35 per sheet. There are about 145 2½" common nails per pound. Fastener estimates for dimension lumber are often estimated by the board foot of lumber in the building. For example, it takes about 20 pounds of 3½" nails for every 1000 board feet of roof framing lumber. Each lineal foot of 2 6 is 1 board foot so, if 2 6s are used for the ceiling joists, stub joists, and common rafters, 920 board feet are required (288' + 88' + 544'). The hip rafters will be 2 8s (which have board feet per lineal foot), so = 107 board feet are needed. The total is 1027 board feet, so just over 20 pounds are needed for the roof framing. It s most common to purchase nails by the 50-pound box. Leftover nails move from job to job. There will be several deliveries or trips to the lumber yard during the construction and getting another box of nails is easy, as long as the carpenter anticipates the need and has the nails on site when required. # of pieces Length Total Lumber order Ceiling joists 24 12' 288' lineal 24 12' Stub joists 22 4' 88' 11 8' Ridge 1 12' 12' 1 12' 1 8 Common rafters (including jacks and end 34 16' 544' 34 16' commons) Hip rafters 4 20' 80' 4 20' Sheathing 33 4' 8' 981 sq feet 33 sheets Fascia 2 12-foot per end 3 12-foot per length 116' 10 12' Fasteners 35 per sheet of plywood 2½" = per pound = 8 pounds Fasteners Joists and rafters 3½" 20 lb./1000 bd ft. 20+ pounds H clips 4 per sheet of plywood Figure 2 Spreadsheet for estimate of material 4 33 = H clips BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 47

48 Learning Task 6 Competency H Typ Typ Figure 3 Plan view of metric hip roof Ceiling joists Stub joists # of pieces Length Total Order (2 1.2) = 7.8 m = = 14 per side 2 = = per side = 13 2 = m 202 m 28 12' 1.2 m 32 m 13 8' Ridge ' Commons, end commons, and jacks Hip rafters (including overhang) Sheathing Fascia = = 18 per side 2 = end commons = (line length + overhang) 205 m 38 18' m 4 24' ( ) / 250 = sq.m. 4 sides = sq.m. per 4' 8' sheet (11.4 2) + (8.4 2) = 39.6 m = 41.3 sheets = (round up to 44 sheets) Lengthwise: 4 14 Widthwise: 4 14 Figure 4 Metric estimate of material Now complete Self Test 6 and check your answers. 48 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

49 Learning Task 6 Competency H-5 Self Test 6 1. What do waste factors depend upon? 2. Referring to Figure 2, how many board feet of commons, end common, and jacks are ordered if 2 8s are used? 3. How many pounds of nails are required for the material from question 2? BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 49

50 Answer Key Competency H-5 Answer Key Self Test 1 1. a. common rafter b. wall plate c. ridge d. common e. hip f. hip jack g. end common 2. double cheek cut 3. single cheek cut 4. Check answer with instructor. Self Test 2 1. rise and 17" (rise and 354 mm for a metric roof) 2. rise and 17" (354 mm for a metric roof), mark on the 17" or 354 mm 3. 28'/2 = 14' (14 units of run) 14 units = = /16" mm / 250 = 1.8 units of run LHPUR for 175 in 250 = 305 mm 1.8 units 305 = 549 mm 5. Check answer with instructor. 6. 4th jack length = 4610 (4 768) = 1538; plus 768 overhang = 2306 mm; 18' = 5486 mm Off-cut = = 3180 mm 7. 3rd jack rafter, including the overhang is 3074 mm 50 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1

51 Answer Key Competency H-5 Self Test /16" 2. 16½" 3. Your drawings may vary LCPUR = ( )= " ( ) 16 = 19.23" = 19¼" LCPUR = ( )= 320 mm ( ) 600 = 768 mm Self Test 4 1. The commons that form the tripod are set first and the ridge placed between them, similar to a gable roof. The end common is added next. 2. The top corners of the double cheek cuts of the hips should be flush with the top edges of the commons. 3. The top edge of the single cheek cut of the jack should be flush with the edge of the hip. Self Test 5 1. Hook the chalk line on a nail at the working point at the top and pull to the corner of the fascia each time to ensure a consistent straight line. 2. LCPUR and unit of run (mark the cut on the unit of run) 3. Width of panel-type sheathing: 48" = 1219 mm 2 2 LCPUR = ( )= mm = X 1219 X = 952 mm Self Test 6 1. the design of the building and experience of the builders ' = 912 board feet 3. ( ) 20 = pounds BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 1 51

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