How do you install the header, king studs, and trimmer studs for a window or door opening?

1 Choose the right lumber

The first step is to choose the right lumber for your framing. You need to consider the size, grade, and moisture content of the wood, as well as the building codes and regulations in your area. Generally, you want to use 2x4 or 2x6 lumber for the studs, and 2x10 or 2x12 lumber for the header. The header is the horizontal beam that spans the top of the opening and transfers the load to the king studs. The king studs are the vertical members that run from the bottom to the top plate of the wall and support the header. The trimmer studs are the vertical members that support the sides of the opening and the window or door.

2 Mark the layout

The next step is to mark the layout of the opening on the wall. You need to measure and mark the width and height of the opening, as well as the rough opening size. The rough opening size is slightly larger than the actual window or door size, to allow for some adjustment and shimming. Typically, you want to add 2 inches to the width and 1 inch to the height of the window or door size. For example, if you have a 36-inch by 80-inch door, your rough opening size should be 38 inches by 81 inches. You also need to mark the location of the header, king studs, and trimmer studs on the wall. The header should be flush with the top of the rough opening, and the king studs should be aligned with the edges of the header. The trimmer studs should be spaced 1 1/2 inches from the edges of the rough opening, to allow for the casing.

3 Cut and assemble the framing

The final step is to cut and assemble the framing for the opening. You need to cut the header, king studs, and trimmer studs to the right length, according to your layout. The header should be twice as thick as the wall thickness, so you need to nail two pieces of lumber together to form the header. The king studs should be the same length as the wall height, and the trimmer studs should be the same length as the rough opening height. You also need to cut two cripple studs for each side of the opening, to fill the gap between the header and the top plate. To assemble the framing, you need to nail the header to the king studs, and then nail the king studs to the top and bottom plates of the wall. You also need to nail the trimmer studs to the king studs, and then nail the cripple studs to the header and the top plate. You can use 16d nails for the header and king studs, and 8d nails for the trimmer and cripple studs.