Once the walls have been plumbed and lined you can begin the cut and install the rafters of the roof framing. To begin this process, you need to know the width of the wall in the direction of the pitch. Divide this number by two and mark the spot on the two ends. Look through your pans to establish what pitch of roof you’ll be cutting. A 5 and 12 pitch means that the roof rises 5 inches for every 12 inches it goes in. but before you can install your first rafter you need to place your ridge member. These can be beams or 2X materials also. In order to know the height of the top of the ridge you simply Multiply the pitch of the roof by the distance to the center of the wall.
Example if the wall is 24 feet wide and you have a 5 & 12 (24 divided by 2 =12) then multiply 5 X 12= 60 60” is 5’. Now multiply the width of the ridge you’re installing remembering that the ridge must be thicker than the rafters to accommodate the angle of their cut.
If your ridge is a 2×12 these members are usually 11&1/4 inches so cut your temporary brace 4’&3/4” determine this line throughout the center of the area then place and brace these temporary supports. Once this has been accomplished measure the distance from the top edge of the ridge of the ridge to the far edge of the wall the rafter will be setting on. Do this for the other side if you have the ridge centered this number will be the same. If yours differ then make them the same. Let’s say your number is 158 inches. If you have a 2×12 ridge you would have 2×10 rafter that are cut from 2x10x16’ materials. Pull one of these boards and lay it upon you saw horses or cutting table. Look down the narrow side of this member to determine the crow or the bow of the board these always go up. Take you square out and place the 5’ mark on one edge and the 12” mark on the same edge. I like to put brass stair guides on my square to mark these locations. The angle of this cut should be towards the crown of the member. Cut this angle. Then take your measuring tape and hook the point of the angle and pull across the board to mark the seat of the rafter at 158”. This is an ark, not a line. Take your again find the 5 and 12 pitch positions square and but this time the angle of the ridge or the short side of the square isn’t used the long side is, the square gives not only the ridge cut, the opposite angle given is the seat cut. If you want your rafter to have 3 &1/2 inches sitting on the top plates then side the square up or down until this angel give you the 3&1/2 inches you desire take you square and mark the right angle from the intersection with the line of the angle being the establishing line. Mark this point. Use it to establish the line. If you do not want any tail then that is your cut. If you want a full tail then only cut out the small triangle you marked out. If you want 2×6 tails then measure from the top of the rafter down 5 & ¼ inch in a few locations of the tail area. Scribe the line from the end to the intersection where it crosses the line if you would have left no tail. Carefully cut this out and then dry-fit it. The nailing method used should be in the pains but typically its five nail through the ridge into the rafter at the top and 2 and 1 into the top plate these nails are 12 g commons. But you plains may calls out hangers or nailing the rafter into the ceiling joist.
If this fits properly use it your pattern and cut four more. These rafters center and support you ridge at each end after being placed on opponent sides at the ends. Cut pair of these rafters off this pattern and place them in the location of every forth or fifth rafter set. Once this has been achieved the temporary support braces are no longer needed, however you do need diagonal bracing to keep the system from falling to a side. simply nail a 2x member to thew ridge and to another 2x member on a cross member running the direction of the ridge. I tend to do this after the first rafter have been establish and plumbed.
From this point your simple fill in the missing rafters one side at a time then do the required blocking. As you fill in the rafters the ridge become straight. If you can trust your cutting then these rafters will cause the wall or the ridge to come into alignment, your walls have been plumbed and lined and the bracing is still up the ridge’s location is established. When this has been finished you may snap you line ate the desired tail length and cut the tails as desired. If you are going to hang fascia the ridges angle is used for the plumb cut.
Once the rafters have been sheeted and nailed of properly the braces from the aligning the walls may be removed.
Note: Images on this blog site are from a free source or taken by the author. No image or group of photos is intended to represent the people the author serves. The author does not care about Race (that is a politically correct term that he does not like because we are all of the same Race, the Human Race. He prefers the term ethnicity, color, religion, sex, gender, marital status, disability, genetic information, national origin, source of income, Veteran or military status, ancestry, citizenship, primary language or immigration status.) He is a service provider for all people. We will all rise together when we band together and help one another. Joseph Erwin is a Real Estate Broker, DRE # O2131799, and a CA general contractor # B 696662. He’s a member of the CRMLS and The East Valley Association of Realtors located in the Inland Empire region of Southern California.
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