To build the roof, I begin by making a template for the base. To lay out the framing, I only need two measurements from this bay window. One is the overall width: 62¼. The other measurement I need is the overall depth. But I have to realize this window is going inside the rough opening 4 inches. So I draw a line all the way across, 4 inches out—and now I measure from the outside of the window to that line, 17 7/8 inch; that’s my overall depth. I want to copy the shape of the head board onto a piece of ¾-inch OSB. This will be my guide for framing. First, I draw a rectangle centered on the sheet, using my 62¼ by 17 7/8 measurements. Then, to get the 45-degree angles, I measure in 17 7/8 inch from each end and draw the lines. Now I have an exact replica of the bay window top. But before I begin the roof framing, I have to add a roof overhang using a strap of soffit material. What I want to do is extend that out because I’m going to have a soffit overhang of 4½ inches. Line the soffit material up with the outside edges—just extend those lines right out, which represents the outside edge of the framing—all the way around.
All Videos in This Series
Now that I have outside edges, I measure from point to point to get my first set of cuts. The right is 31 7/8, and the center 30 inches. And the left is the same as the other side; 31 7/8. And this piece will have a 22½-degree angle here, and a 45 on the other end. This piece will have a 22½-degree angle on both ends, and this piece will have a 22½ here and a 45 there.
I’m going to lay them out, right along the lines, and outline the outside of the frame. Then I measure the inside—71—so I’ll cut that, put it in, and then I’ll have the base framed up. All right; that fits well. Next, I’ll cut these miniature joists to fit in here. Then all I have to do is fasten everything together. I have to put blocking in so that when I put the trim on from underneath, it’ll have someplace to catch on the outside edges.
