I have always found that windows do a lot for a home. They help let in air and light into your home. They add a tonne of visual character to the outside of your home. But there are downsides if they are not installed properly. Water can find its way into your home and also cold air in the winter if not sealed properly. This can also cause some rotting to happen around the window over time. So lets go through the steps to properly install a window.
First of all lets look at Windows frame and rough opening as the following diagram displays.
Instructions To Protect Against Water Infiltration:
1. Measure your rough opening from all angles (Top, Bottom, and Middle)
2. If you notice that there is a opening larger than the difference between all three widths or notice one of your measurements height measurement of the opening is more than 1 inch you will need to cut some tapered filler strips from you stock of studs and nail them to the sides that are not level.
3. The outside dimension of the window should only be about 1 half an inch shorter and 3 quarters of an inch narrower than your smallest width/height measurements.
4. If they are not then you will need to order a new window to fit these dimensions or you will need to re-frame your window again.
5. Now its time to keep the water out by cutting your self-adhering water proof membrane or builder’s felt.
6. You will only need about 6-inch wide strip of the self-adhering water proof membrane or about 9 to 12 inch wide strip of about a 15 pound builder’s felt give or take.
7. Make sure it is about 18 to around 24 inches longer than the whole windows width
8. Also make sure that the top edge of the membrane/felt does not go above the edge of the opening otherwise you will have problems.
9. Along each side of the opening cut yourself 2 more strips of membrane or felt about 1 foot longer than the entire opening height.
10. Make sure they are center and hook them up along each side of the opening of the window and also make sure they are completely overlapping the strip under the window.
11. Along the top cut yourself another strip of membrane or felt 1 foot longer than your window width
12. Make sure it is center and attach it across the top of the rough opening and also make sure it overlapped the 2 side strips.
13. Make sure your seams never face upward at all to prevent water from getting in.
14. Now you can start going through the steps of installing your window without having to worry about water