Why use a birdsmouth

GP, for example, has a 52 page technical manual available for free download. The documents have detailed pictures and installation instructions. As mentioned earlier, I have a friend who is a framer.

He primarily built high-end homes in California. His experience there was vastly different than New Mexico due to the earthquake requirements. In any event, we were actually just discussing birdsmouth on I-joists, and he referred me to the GP website. They do not recommend cutting a birdsmouth without beefing up the web. In a non-cut installation, they have a diagram of the i-joist laying flat over a second top plate that has been beveled to the angle of the roof.

This provides more surface area for the joist to rest on, provides a larger nail surface, and another surface for the Simpson fastner. In talking with my friend, he indicated that for a simple gable roof one could use the same technique for traditional 2X framing and save a whole bunch of time. The second top plate would provide enough surface area to absorb transfer the load downward.

He indicated he had seen the technique used years ago. I'll defer to the experts here for additional guidance, as I am not a framer, and my friend is mostly retired. The simpson connector pictured would work well for 2X material. Seems I've hit something here that either people don't know about, or I am very confused This I-beam stuff is used all over but I still don't see how one attaches them to a ridge board or ledger board Seems to me that there needs to be 2X material at both places where the I-beams are attached to the building.

What am I missing? I took a look at the apawood. I guess I understand a bit more, but with all of the stiffening, filler blocks, squash blocks and such required for this engineered lumber, I'm wondering if I shouldn't just go with conventional 2X material.

Do they make 18' 2x8s? Would simplify my project. Thanks for all the input guys. I-joists are quite good for long spans and stiffer floorsI see less value when used for rafters except they are much lighter and somewhat easier to handle up high for small crews. There other advantage is no warping or shrinkage like you sometimes get from the quality of lumber you see now. Quote from: hnash53 on January 07, , AM.

Pages: [ 1 ] Go Up. Divide this figure width of building by 2. Subtract half the width of the ridge plate, and then multiply that number by itself. Finally, add Result A and Result B together and find their square root. This figure will be the length of your rafter where your birdsmouth will be cut. You have to be careful to make sure that the birdsmouth will not be more than half of the total depth of the rafter. On the rafter, you want to cut, measure its overall depth, and divide it by 3.

Using this figure, measure and mark two points on each side of the vertical line, which indicates where the birdsmouth will be cut. It is going to intersect with the plumb line that specifies the location where the heels and seat cuts intersect at 90 degrees. Flip the square over so that the short side is to the left. We will leave an overhang of 9 inches in this example, so slide it to the left with your framing square in the same position as it was in the step above, making sure that the 8 and 12 marks stay on the bottom edge of the rafter until the 9 on the long side is inline with the plumb line.

Using your circular saw, cut along the plumb and horizontal lines. Be careful not to cut too deeply. Remove the little triangle of wood and admire your new birdsmouth cut. Next, test the birdsmouth cut by setting the rafter in place. Does it have the correct angle for the roof pitch you want? After double-checking everything, you may need to adjust your calculations and cuts. As with any project involving saws, make sure you follow all safety protocols.

Sometimes this technique is called side-nailing or skew-nailing. When installing the rafters, you will need two assistants. Step 3 — Install the Rafters. Step 4 — Install the Other Rafters.

Step 5 — Cut the Rafter Ties. Step 6 — Fit the Rafter Ties. What is the difference between ceiling joists and rafters? The main difference between Joist and Rafter is that the Joist is a horizontal structural element transferring load from flooring to beams, typically running perpendicular to beams and Rafter is a structural members in architecture. Can ceiling joists run perpendicular to rafters? Rafter ties resist the outward thrust that rafters exert on the exterior walls.

When ceiling joists run perpendicular to the rafters, inspectors may find rafter ties installed above ceiling joists as framing members every 4 feet running above the ceiling joists connecting opposing rafters.