If you are working on an old home, the windows may be badly degraded. If they were neglected long enough, or simply weren't installed correctly all those years ago, the window frame will need to be replaced. Here is what you need to concern yourself with in order to ensure correct installation.
Ensure the Window Frame is Properly Sized & Braced
When framing out a window, start at the top and work your way down. The header piece needs to be able to support the layers above and distribute the load to the side studs. The header piece should consist of two boards, flipped so that the width is facing the room, rather than the same direction as the other studs. In addition, it is vitally important that this piece reaches all the way to the studs on each side of the window. This will allow it to distribute the weight from above the window onto those studs instead of pressing down the window.
Once this crucial piece is in place, you can finish framing out the window itself. Add boards along where the sides and bottom of the window will go to give you something to attach the window to. Take your time and ensure that the opening is square and that the window will fit into the opening securely.
Give the Window Frame Plenty of Support
While the header will take care of the weight above the window, it won't do anything for the weight of the window itself. To do that, you need to add additional supports called jack studs or cripples. They should be spaced at the same intervals as the studs above and below. By placing them above and below the window they ensure the weight is securely supported, and that the window won't be able to shift position as the years go by.
Depending on the size of the window, now is the time to add additional support as needed. In particular, large windows may warrant doubling up on the sill, sides, and jack studs to ensure that nothing warps over time. When in doubt, the documentation may lend some insight on whether you need this additional support.
Make Sure the Window Is Completely Secured to the Frame
Now that everything is prepped, it is time to actually put in the window. If you've never done this before, the internet will be your friend, or (perhaps a better choice) you can follow the directions that came with your window. This is not a time for rushing the installation; pulling out a window and reinstalling it because you made a mistake can easily damage the integrity of the window.
There are two main things you need to concern yourself with during the installation: ensuring the window frame is sealed and it is securely fastened. This is not the time to be saving money by skipping caulking or insulating the window, and you should never skimp on nails during a remodeling project.Only once you are sure that the window is secure, sealed and level can you turn your attention to the final details like attaching trim and painting the frame.
Poorly framed windows have a tendency to leak, and can damage the window over time. By framing your new windows properly, you can ensure that it will work wonderfully for years to come. If you aren't up for the challenge, your local contractor like Five Star Windows Inc will be happy to be of assistance. Fortunately, once the window is in properly, maintenance will be a breeze. If not, you will be constantly trying to fill in cracks with caulk.