Cutting birdsmouths for rafters

Discussion in 'Shop Talk' started by Salmonberry, May 23, 2006.

  1. Salmonberry

    Salmonberry Registered Nut

    Feb 28, 2006
    Not ever having made any birdsmouth cuts I've got a question about the procedure. Is the cut made similiar to cuts made for stair stringers where a skilsaw is used to make the initial cut followed up by using a handsaw to prevent from overcutting the mark?
  2. Gideon

    Gideon Well-Known Member

    Sep 14, 2005
    That way will work great. A note of caution--use the same 2X for the pattern for them all. My Dad was "cut man" in his earlier carpenter days and kept handing the original cut up to the roof. When finished the roof had an 8" difference from one end to the other. They had to recut every one. Amazing what a 1/4" difference makes to the pitch of a roof. Dad was a superb carpenter but we all make careless mistakes that are costly-kind of like life.

  3. Blu3duk

    Blu3duk Well-Known Member

    Jun 2, 2002
    central idaho republic
    Since the answer has already been given other folks may like to learn about framing a roof fo various styles... a friend of mine years ago wrote a book on the subject and in my biased opinion it is the best written on topic.... some of his other books were ok but Roof Framing by Marshall Gross is availabe from several online places and can be had from some for used prices but worht everything a person pays..... A person could literally after reading and practicing what is in the book walk onto a construction job and frame a roof [ok so you have to be able to retain what you read and what you practice]

    And for the most part there isnt to many folks who can properly frame a roof anymore, it is becoming a lost art with the materials of todays builders have to use.

  4. tiogacounty

    tiogacounty Well-Known Member

    Oct 27, 2005
    I've cut a few thousand in my time, so I guess I'll throw a tip, or two, in. first learn to do the math with a calculator, or a construction master calculator if the geometry is too difficult. "Stepping off" with a square isn't as accurate. Next pick a great looking piece of lumber out of the pile for your pattern. Make sure it is crown free and flat. Do your layout and cutting on the pattern. Unless the tail is exposed, most cutters don't bother to finish the cut with a hand saw. Now cut another rafter using your pattern. Erect the pair and check the fit. Remember to put a scrap of 2x where the ridge board will go. If everything is cool, take your pattern and write PATTERN on both sides in big letters. This will prevent it from being used to early. Now take two small scraps of plywood (roughly 3"x6") and nail them to the top edge of the pattern near the peak and tail. These are stops, they allow you to slam the pattern tight to your rafters without having to make sure that the top edge is parallel with the pattern. Pre-mark all rafter stock with a lumber crayon, put an arrow on each piece to indicate crown. Make sure the crown (bow) is up on each rafter. This is important, if you don't do it, and end up with a crown up rafter next to a crown down, you will have a noticable dip in the roof. Trace and cut neatly and your roof will look fantastic.