You’re supposed to shim to fit the rough opening.

OK, but if the rough opening is 48" why would you order a 46" window? Seems like this is a wide, unnecessary shim. Thank you so much for responding and sorry I am so clueless!

Are you more concerned with the 1x4 material (effectively a buck frame) around the perimeter, or just the "filler" on the sides?

If anything, you should have a similar gap on the top and bottom, properly measured windows do not fit "tight". They need space in case the opening is racked, space for shimming, insulation foam, etc.

In most cases, for a new construction type of installation, a standard cut back is 1/2" or so, so in that case a 47" width would be ordered for a 48" RO. Some installers take off a little more, some a little less. At the end of the day, its hard to know whether this is right or wrong without knowing what was specified in your contract and/or discussed.

As far as weatherproofing, this can certainly be sealed well if its done properly.

Perhaps a standard sized model was ordered in order to not have to triple your budget with a custom size. There is nothing essentially wrong with what you’ve shown. If it’s flashed correctly outside. (I don’t see any pan flashing there, but there isn’t enough info to judge.). And it must be waterproofed correctly inside. What waterproofing system are they using there?

Thank you, HomeSealed. Would your information about the 1/2" cutback be the same for replacement windows (what this is)? The contract specified nothing about the actual size of the window. The GC came out one day and measured. The manufacturer then sent him a drawing with the size specifications and configuration, which he forwarded to me. I assumed, since he measured himself and it looked good to him, that all was correct and told him to go ahead and order. The windows are twice as off on the width as on the height.

Would like your opinion as to how to approach this. We are going to meet with him tomorrow. Thank you!

Typically I would order a window 3/4“ under rough opening and that is after leaving enough room to taper the sill. It is more difficult to get the exact measurement when there is an existing window there as in old construction like you have. In cases like these the outside dimensions are typically what I like to use. I’d be curious on what they did on the outside. The interior side can be covered by trim or tile. I would have like to have seen a tapered sill , flashing and room for shims and foam.

For the outside, they've framed it in and will cover it with flashing. So should I make a big deal of this, ignore it? I'm just disappointed they missed it by at least an inch on the width. The window appears so much smaller than what it is replacing. Let me know how you think I should talk to the project manager tomorrow or if you think I should just let it go. This is the third mess-up they've had and we've just started. Thank you so much!

You flash, then install the window. Widows aren't "covered" in flashing.

Celadon, thank you. They are using the Schluter-Kerdi system. It's dark and raining now, but in the morning I hope to take a picture. I hope it's OK!

I'm not sure if it's universal, but when I had replacement windows done in my home (Kolbe Wood Windows) they all appeared smaller than the original windows. I was upset, but then did some looking around and it seems I read that the actual glass area would likely be smaller on replacement windows.

@Deanie Jo, can you post up any exterior pics? I would say no, it's not worth making a big deal about the size as there may be some unknown circumstances and its not very far off. That said, it would certainly be worth making a big deal about it the overall install was poor. While the pics shown so far don't confirm that without a doubt, they leave the door open for that possibility.

Hope you can tell from this. It's dark out, but my camera has a flash. Thanks.

looks fine. i would not order a new window over that.