How to Frame in Windows to the Outside of a House

Whether you are building a new house or adding an addition to an old one, it is very likely that you will have to create a rough opening for a window. As you work, remember to always keep the window opening level and plumb. Here are a few suggestions to do the job correctly the first time that you attempt it.

Things You'll Need

• Circular saw
• Sawhorses
• Galvanized framing nails (#16)
• Safety glasses
• Carpenter's square
• Tape measure
• Framing lumber 2-by-4s
• Header material (2-by-6s or 2-by-8s)
• Plywood (3/8-inch)
• Box nails (#8)
• 4-foot level
• 2-foot level
• 20 oz. framing hammer

Instructions

1. Obtain the size of the rough opening from the window manufacturer.

2. Transpose the size of the rough opening to the bottom plate of the wall. Mark the location on the top side of the plate for the two double posts that border the window.
   For example, if you have a 36-inch rough opening for a window, and the opening begins at the 4-foot mark from the edge of the wall, then you will have to make two perpendicular marks on the face of the 2-by-4 plate. One will be at 48 inches, and other will be at 84 inches. The first mark will be proceeded by two 2-by-4s (This is a double post), and the second mark will be followed by another double post. Each post will take up 3 inches, so mark that distance on the plate and put a big, visible double "X" to mark the exact location for each post.

3. Put the wall together and raise the wall into place. Every stud or post should be true and plumb in both directions, especially the double posts for the window. Double-check this with a 4-foot level.

4. Cut a 36-inch piece of 2-by-4 for the sill. Calculate the correct height and toenail the board into place between the two posts. This board must be level. Check it with a 2-foot level.

5. Place jack studs underneath the still. They are just 2-by-4s that run from the bottom plate to the sill. They should be in line with the other wall studs at 16 or 24 inches on center. The posts may or may not be part of this pattern.

6. Build a header for the top of the window. It will usually be made from two 2-by-6s (2-by-8s if the window is wide) and a piece of 3/8-inch plywood. All pieces should be 36 inches long (the plywood is 5 1/2 inches wide), and they get nailed together to form one unit that is 3 1/2 inches thick.

7. Nail the header above the sill near the top plate to create the correct height of the window opening. This piece must be leveled and then nailed tightly with framing nails. Use the smaller box nails to put the header together.

8. Add the cripples. These are 2-by-4s that line up with the jack studs and run from the top of the header to the bottom of the top plate (the top plate is also a double plate). Toenail these with the framing nails.

9. Go 1 foot on both sides of the posts and add a single upright 2-by-4 stud on each side. Nail these at both the top and bottom, and then place blocking (several horizontal pieces of 2-by-4) between this stud and the adjacent post.

Tips & Warnings

• Don't split the blocking; space the studs at least a foot apart.

• Be careful if you use a pneumatic gun to do the nailing.