You most likely have new construction windows at present. New construction windows go up from the outside by nailing through a nailing fin into the framing. Replacement windows, block or jamb liner styles, fit into an exisiting window jambs. With new construction windows and wallboard wraps you probably don't have suitable jambs to use with replacement windows.

Thanks for replying jan9. Can you tell me what it is about sheetrocked windows that makes them unable to accomodate a replacement window frame Trying to wrap my head around this, since my wallboard has not been opened up yet, and none of the concept of window installation makes any sense to me. I do get that new construction has the fin on it, but I just cant figure out why the current return makes a difference.

jess111,
I've installed windows here in the Northeast for thirty years for various companies.
Sheetrock returns are very common here and an experinced window professional will know what to do. It's a no-brainer to him.
First your new vinyl replacement opening size will be the the smallest width measurement (sheetrock to sheetrock), check bottom middle and top.
Go with the smallest width. Remember sheetrock returns are usually not all the same. You have to measure every one.
Measure the opening height the same way.
Now you have your correct window opening size. All mfgrs. will take your sizes and cut down the width 1/4" and 1/2" to 3/4" on the height. The window comes with a U-Channel top that is attached to the new window that can be slid up to fill in the top daylight of the opening.

99% of VRWindows measure 3 1/4" thick. ( Pella's Impervia is 3" even). Whether your return dimension is more or less, it doesn't matter.

Your window removal is difficult, but done all the time. I'm not going to explain the step by step proceedure here as a professional window installer and exterior metal trim man will know what to do.

Sheetrock openings are very common. Your origional windows are also very common, you just need to get people who know how to the job. REPLACEMENT WINDOWS CAN GO INTO THESE OPENINGS!

Good Luck,

The PorchGuy

Here is a link that might be useful: My Album

thank you for the info porchguy! I really hope I can have this done with replacement windows. Does anyone have any recommendations for how to go about finding a reputable window contractor in NJ? I really don't want to use a fly by night window company, but I don't want to get hosed by an Anderson or Pella replacement dealer, and not too into using a big box store for windows. I just need basic, double hung, low E, and argons I guess, with a contractor that knows what he's doing. This is tough, since I know nothing about windows. Meeting with tile, granite, and cabinet guys was a breeze. This....ugh!!! I just want it done right for a reasonable price.

jess111,
Maybe I can help you. I'm in New Jersey. Email me.

Thanks,

The Porchguy