The Speed Square : Swanson's Book of Rafter Lengths and Roof
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t THE SPEED "SPEED LINE " SQUARE SWANSON'S BOOK OF RAFTER LENGTHS AND ROOF CONSTRUCTION Frame Your Roofs as Easily as Your Studdings or Joists You've got our Square .. Now, Get our Saw Set! HEAVY D UTY SAW SET Stop f ighting dull saw blades. Reset the teeth with a SWANSON SAW SET ENLARGED SECTION Fast and Easy - Right on the Job OF DEGREE SCALE (see inside back cover for more detail) 10 15 • I • I THE SCALE. o.,o DEGREES. ACROSS BOTI0h4 (LONG Write to Swanson Tool Co. for current LEG) OF SQUARE ALLOWS US ER TO ""4ARK AND t,,,1EASURE HIS WORK IN DEGREE S. THE LONG LINES prices, or ... see your local dealer. WITH A HEAVY BLOCK LINE BETWEEN MAKES IT h4UCH EAS IER FOR THE EYE TO PI CK OUT A LOCATION ON THE SCALE. Nol• : E•d1 hu ... y blod Ii"• i1 1° SWANSON TOOL COMPANY, INC. wide. Eed1 1peu i1 2° wide . P. 0 . Box 434, Oak Lawn, Illinois 60453 Ph one : (312) 599-9 029 THE "ONE NUMBER" METHOD COMMON RAFTER : One running at right FOR ANY PITCHED ROOF angles (90°) from plate to ridge. The common rafter will form the diagonal leg (hypothe The one number method developed by the nuse) of a 90 ° triangle, with the rise and run Swanson Tool Co. simplifies roof framing to forming the 90 ° angle of the triangle ( Fig. 1) . where roofs are really framed as "easily as your studdings or joists." Fig. 1 also shows correct points from which to measure. Study them and remember the Following is a brief description of the vari picture when you are on the job. Where the ous rafters, how to get the different cuts, arrows show I• Rafter Length •I. these are where to measure from, what is meant by the lines to measure from. When your lumber "run" and "rise," information about the hip is not straight, always put the crown or high and valley rafter, etc. side up when laying out any rafter. When lay This book has been rewritten with the use of ing out rafter as shown in Fig. 1 (lets assume more pictures in the hope it will be of greater 5" rise), start at top end of rafter. Lay s:i:uare benefit to those who are not as familiar with on face of rafter, with "T" bar of s:i:uare roof construction as the tradesman. Good plan down over the edge of rafter. Pivot S1Uare to ning will save time and material. where number 5 on common scale lines up with same edge of rafter as pivot point. Keep pivot point tight against edge of rafter. Start your mark at pivot point, marking along top edge of square. See drawing in front of book. NOW WITH FULL 90 DEGREE SCALE This gives the top plumb cut, to fit against The square has been redesigned with the ridge. addition of a full 90 degree scale, which will M easure the rafter length along top edge of enable the user to mark any angle in degrees, rafter. Mark another plumb cut same as above. as well as all the angles represented in "inch This line represents outside wall of the build rise per foot run." You can easily· convert de ing. (The same point from which you meas grees to inch rise or vice versa at a glance. u·red the width of the building). Add what The square makes an excellent guide for the ever length you want for a tail or eave to the electric saw to run against and is very handy rafter lengths given in the table in back of for trim work. book. Mark at end of tail on rafter is plumb 2 3 cut, same as one at top end of rafter ( Fig. 1). common rafter rises 12" in only 12" of hori The tails of the rafters may be cut on the zontal run. This requires a different angle for ground, or wait until rafters are all in place the plumb cuts. In Fig. 4, square is held on and mark t he ends to a line and cut- what ever r after and pivo ted in the same manner as wit h is the easiest. To get the Bottom or Heel cut a common rafter, but using the Hip-Val scale. see Fig. 2. If building is out of square, one hip will be cut a little shorter, depending on how great VALLEY RAFTER: One running diagon the error is. Keep longer corner at top end of ally from the plate to the ridge at the inter hip u·p even with top of ridge. Keep ridge and section of gable extension with main roof hips well propped up until roof boards are ( Fig. 7) . nailed. Watch that you don't put a bow in HIP RAFTER : One running diagonally ridge or hip while nailing other rafters to from the plate to t he ridge (Fig. 7). them. Since both hip and valley rafters run at a To find intersection points of center of hips 45° angle to the common rafter, they both on ridge, leave ridge about a foot too long at represent the diagonal or hypothenuse of a point where both hips intersect the ridge. right triangle; the three sides being the h ip, Take a regular length common rafter (such plate and common rafter, or the valley, ridge as used on main roof). Set bottom cut over and common rafter. Therefore, the cuts and edge of plate and in line with ridge. Make sure lengths apply equally to hip and valley rafters your walls are straight. Place top end of com (Fig. 3) . mon rafter along side of the ridge, bringing You will notice the square has a separate top point of common even with top of ridge Hip-Val Scale which must be used for either ( Fig. 5). Mark across top of ridge at this of these two rafters. But always use the s a ' )'W point. This mark is the center line of the two number on Hip-Val scale as yo u used on t he intersecting hips. The common rafter used to common rafter scale- the number representing get this intersection point would be placed in inch rise. The reason for the separate Hip-Val the same position as the one in Fig. 7 that scale is that the hip and valley rafters run at comes in line with the ridge and runs under 45 ° to the common rafter, and therefore must neath the little dormer on the 20'0" wall side. be longer. In Fig. 3, the hip rafter has a This way you know the rise of the hips will horizontal run of 17" to rise 12", while the be the same as the rise of the common rafter 4 5 on main roof. Leave the bottom ends of the sate for 1/z of the ridge thickness ( or for hi ps (eave end ) a li ttle short so they will :not jacks, % of valley or hip thickness). There is interfere with lining up the facia boards at no problem in laying out these angles on t he the corner. rafters as long as you keep in mind which side of the hip ( or whatever ) you want t he rafter JACK RAFTERS: One which does not ex to fit against. Usually a carpenter will space tend from plate to ridge. Hip Jack - one run the ceiling joist from an outside wall and ning from plate to hip at 90 ° to plate. Valley working to a 48" center. This gives proper Jack - one running from ridge to valley at spacing for dry wall or panelling 01' wh '.l tever 90 ° to ridge. Cripple Jack - one which neither is used. Proper spac ing of ceiling joist wi ll ai d touches the ridge nor plate, but runs from a hip in roof construction. Measure shortest jack rafter to a valley rafter at 90 ° to the ridge first ( usually running next to a ceiling joist) , (Fig. 7) . from plate to hip rafter. The difference in The rise and run of a jack rafter are the length of the rest of the jacks is taken from same as that of a common rafter. When m ark chart. Set each rafter along side ceiling joist ing jacks use the common rafter scale and and spike well. The ceiling joist then ties the same number (inch rise). Where rafter rests roof together. against hip or valley, mark plumb cut. then Figure the rafter material lengths so you· cut at 45 ° angle along this mark. This will can cut a long and short jack rafter from each give both plumb cut and side cut ( Fig. 4 ). piece. When you have cut your shortest jack, When resting on ridge or plate, lay out the the angle of the long end will then fit on the same as for the common rafters. For cripple other side of the hip. Do this all the way up jacks, mark plumb cu ts on both ends and saw the hip, always leaving the cut off end for t he at 45 ° as above. other side. If lumber has crown in it, put When measuring the length o'f the jack crown up on longest cut off piece. rafter, measure from longest corner (plumb In some cases a carpenter will build the cut on 45 °) to other plumb cut mark. along valley on top of the main roof, not using a Top Side (same as shown in Fig.