Are you a contractor or builder? Do you rehab properties often? If so you most likely want to save time, because lets face facts time is money. You might think you can save money buying a stock size window from Home Depot or Lowes, and with our experience not many Philadelphia homes have standard window sizes. So what is your alternatives? Go buy a standard size window that is 2 inches to short and 1 inch to long you can deal with the height, but the width you are going to have to make up the space with extra work and effort. You will need to pack out the window frame, finish the inside, then treat the outside, by the time your done you spent more time building the frame than installing the window itself window. If you have a standard window that fits the opening correctly great! We recommend 1/4 off the width and a 1/2 off the height for your opening, Anything over the top more is very difficult to make up with caulk. We recommend any contractor to get the proper size window for the opening, now this much be more expensive than a standard window but it will SAVE YOU TIME and EFFORT! Also the job looks much better. Feel free to email us with any questions.