Bay-Window Roof: How to Build the Wall Cleat

Now that we’re done with the template for the base, I’m going to remark this a little bit to create the cleat, which is the nailer for the rafters against the wall. The first thing I do to get the right proportions for the cleat is a really neat trick: Measure the outside edge of the angle and just swing it along inside, and mark that spot so I have the same distance along the bottom here; then I simply transfer that mark up to the top edge of the nailer and go from that spot down to the outside edge–and that’s the roof angle.

Now I do the same to the other side. Measure the top edge of the angle, mark it along the bottom, transfer to the top, and draw a new line for the angle at the cleat. All I have to do is cut it out.

From this point, follow the red line up to the top, cross to this line, and follow the red line down. Once we cut it out, we’ll have our rafter cleat. Here’s the rafter cleat that gets nailed up against the wall like this. The size is correct along the length-except we have one problem right here in the corner. The rafter cleat is the right size-the back of it comes even with the outside edge of the framing-but because the framing is at a 45, the front of the cleat sticks out ¾ inch. That’s no good. We can adjust this in two different ways. One way is to cut a bevel along the entire rafter cleat-along the top and down the other side, about 45 degrees-and that would make this come even. A simpler way of doing it-which would actually bring it back like this-is to cut ½ inch off the bottom, so when we raise it up, the front edge is even with the framing. The only thing left is cutting the rafters.