Conventional Wood Roof Framing Terms and Tips

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Trusses? We don’t need no stinking trusses! Not when you conventionally frame everything! Well, actually, you might need trusses. If so, check out our article on building with trusses. While this tough task isn’t for everybody, it does look good (but it might not be cheaper than trusses). Go old school on your next framing project by using these tips, terms and techniques for conventional roof framing.

Roof Framing Lingo

There is a little bit of terminology that you need to know before you break out the framing square and saw. The following list includes a few of the basic terms you’ll need to know before you can talk the conventional roof framing talk:

  • Rafter/Ceiling Joist- These are the boards that support the roof sheathing. There are common rafters, hip rafters, jack rafters and white water rafters (the latter isn’t part of your framing though)
  • Common Rafters – The main rafters that support the roof.
  • Hip Rafters – The rafters that create the hip on a roof.
  • Valley Rafters – The rafters that create the valley of a roof.
  • King Rafter – The longest rafter on the side of a hip roof line – also known as the Elvis rafter.
  • Jack Rafter – The shorter rafters that connect to the king rafter on a hip roof.
  • Barge Rafter – The rafter on top of a gable end. Sometimes it forms the roof overhang as well.
  • Collar Tie – This board provides additional support underneath the rafter where it comes together at the ridge board. It is not something you have to wear with a tuxedo.
  • Seat Cut – This is the notched cut where the rafter board sits on top of a wall’s top plate. A seat cut also happens when you are wearing tight pants and you bend over and hear “Riiiippp”!
  • Heal Cut – This is the perpendicular cut to the seat cut that runs down the length of the wall. It’s also when you step on a razor blade with your foot.
  • Birds Mouth – This is where the seat cut and the heal cut come together to form the shape of a birds mouth. No joke needed here, it’s funny enough sounding on its own.
  • Ridge Board – This is the solid piece of wood (typically a 2×12 or larger) that spans the length of the roof to create the ridge. The rafters all tie into the top of this board to form the peak of the roof.

I could really go on and on with terms and definitions, but it might take up a few pages and you’d fall asleep, so we’ll just skip to the more important parts of the framing.

Valley rafter

How to Layout a Common Rafter

Common rafters are one of the easiest types of rafters to layout. Since you’ll be using more than one of these suckers, it’s a good idea to familiarize yourself with this method before getting into the tougher stuff.

To layout a common rafter, first you’ll need to know the pitch of the roof. For this demo, let’s just say our roof pitch is going to be a 6/12 pitch. A 6/12 pitch simply means for every 12 inches of run (the horizontal distance of the rafter) it rises 6 inches.

Start at the top of the rafter and mark a common 6/12 pitch. On the long part of the square, you’ll need to find the first 12 inch measurement and make a small mark. Now you can step down with the square to complete the total run of the rafter.

Valley, hip, ridge and common rafters
Valley, hip, ridge and common rafters – sorry it’s so dark!

Once you get to the end of the run, you can create the bird’s mouth. Measure from the heal cut the width of the wall to create the seat cut. Now you can simply flip the square to create the overhang. I like to leave them all long and cut them using a string line later on.

After you’ve got the length all squared away, you’ll need to trim the common cut to accommodate for the rafter. Just nip off ¾” for the perfect fit.

Now you can get to cutting. Just be sure that you use a hand saw to cut the birds mouth out or else you’ll cut too far into the rafter and compromise its structural integrity. Test fit the rafter and if it’s all good, then you can use that rafter as a template to cut the rest. Happy framing!

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About Eric

Since Eric built his first skateboard ramp in his parents driveway; he’s breathed, slept and eaten DIY construction. As a second generation master carpenter who runs two Florida-based construction firms, Eric’s had the chance to work on everything from Mcmansions to your local mall to the cat lady’s bathroom. So when it comes to dealing with construction s@#t; he’s the man—literally. There isn’t a tool or construction material that Eric hasn’t used and abused, and if there is; it’s rocking in a dark corner nervously waiting for him to show up for work.

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3 thoughts on “Conventional Wood Roof Framing Terms and Tips”

  1. Here are some additional hints. Think of the entire roof in terms of the centerlines of the rafters, ridge board, etc. Also, purchase a good framing square. A quality framing square has a rafter table to aid in calculating the rafter length based on the pitch of the roof. For example, on a 5/12 pitch roof, the unit rafter length from the table is 13-inches. (you can also use the Pythagorean thermo to calculate this) If the total run (half the span of the building) is 15-feet, multiply 15 x 13-inches to get 195-inches or 16’ 3” from the birds mouth to the center of the ridge board.

  2. I think you meant cut 3/4″ off the top of the rafter to accommodate 1/2 the thickness of the ridge board. Not rafter.

    “After you’ve got the length all squared away, you’ll need to trim the common cut to accommodate for the (rafter). Just nip off ¾” for the perfect fit.”


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