rafter layout; one of the most interestingparts of construction. i'm robert markey, i've been doing instruction, especially framingand rafters, for many years. i'm going to talk about common rafter layout. okay, we'llassume that you know your roof pitch which is something and twelve. let's say it's nineand twelve. and we'll assume you know your rafter length, okay. and your rafter length;if you don't have it and you just know your
most essential woodworking hand tools, height and your horizontal distance it's thepythagorean theorem, a squared plus b squared equals c squared. it gives you your commonrafter length, okay. in order to lay it out well you can just use a framing square, butif you have these nice little brass thingies it makes it much easier. so, we've got em'set at nine and twelve, put the top of our
rafter. it's our ridge, and actually you want to cutthat first so you got somethin' nice to hook your tape on, and then you measure your rafterlength to the outside of your top plate. and let's assume it's a seventy two inch rafter,so we now make a mark there from the top, come down, okay. so, this is this is yourlength. now, once you have this, the rafter tail, the bird's mouth needs to be dealt withif you're using two by four walls say, or let's say two by six cause' we want more insulationyou could come over five and a half inches. if you got plywood on the outside you'd comeover six, but let's just work it this way. here's your bird's mouth right there, so therafter sits, the rafter's going to sit like
this for your rafter tail, and then it dependsvery much on what your what your trim work, what your corners work is like. and you maycome over here and you may cut this this way, you may cut it straight. you may come backhere and straight up for for something like that, and that's all in the design work, butthe essential mathematical piece of laying out the rafters; here we got it. i'm robertmarkey, and we've been talking about common rafter layout.
