You will get a more cost efficient home from switching out your aluminum window frames for newer vinyl ones that will offer more UV protection as well as insulation. In most cases, you can get windows the appropriate size to replace the old ones without problem. It is wise to take all corner measurements before buying new replacement windows to ensure that they will fit into place with limited alterations made. When shopping for new windows, know that triple pane windows provide better insulation than two pane or single pane units. Be sure you are buying the best ones for your needs and that they have a warranty in place that covers you in the case of breaks and smashes during installation.
Step 1 - Remove the Old Window
The first step is to remove the old aluminum window frames and set them aside. generally, the framing for these are very leaky when it comes to air pressure, as they are simply screwed into the window face. They are held in with screws that go through the window jam and into the framing of your home or workshop. Remove the windows to prevent them from falling out while disassembling them, and set them aside. They should have sliding pins that you simply push to the sides to unlock the windows from the frame. If you tip the window out toward you and then turn it on an axis of 45 degrees, they should just pop out.
Next, you will unscrew the metal jam from the opening where your aluminum window frames come together. The screws should be located along the top and bottom of the unit. Simply remove these, and the jam should simply pop out without too much effort. Once the old metal frame is cleared out, you should be looking at the 2 by 4 inch stud walls across all sides of your opening.
Step 2 - Inserting the New Framing
Once your aluminum window frames are removed and out of the way, you will want to install your new sill. Check your measurements before moving forward to avoid having to reverse your work. If your window is wider or longer than the opening you are working with, you may want to extend the opening outward so that it will fit. To do this, you can use the crow bar to pop out the old studs and then extend them as needed, remember you are going to want 1 to 2 inches around all the edges of the window jam to allow for adjustments going forward.
Step 3 - Installing the Windows
Now you should have a vinyl casing in place where your aluminum window frames used to be. You will want to use the shims and your level to make sure they are level and in place properly before mounting them to the frame. This is to ensure that your windows will open and close and have a tight seal when they are closed. Once you have everything level, simply attach the window frame trimming, which will hide the working parts of the window from view.