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diy'er on LI 09-11-2010 10:33 PM

replacing windows.. modifying a rough opening by less than 2 inches?

we're about to transform our 1st floor office into our son's bedroom. (I already posted our problem about closing off the room from the living room with a door on the remodeling board......)

The (original) windows in the room need replacing. They're in such bad shape that we're not even going with replacement windows.... We intend to replace the entire window, and DIY the installation. **We never installed a window before**

We pulled off the trim molding and measured the exact window sizes. The rough opening (at least the drywall) is exceptionally close to the original window frames. Our local anderson dealership notified us that the old windows are CLOSE to some anderson sizes, but none are exact. Unfortunately, both anderson windows are slightly LARGER than ours. The dealer seemed unconcerned, and said that the size down was substantially smaller than ours (3-4"), and would require adding siding to the outside, and drywall to the inside....
ours: 51 1/4" x 34.... New: 52 7/8" x 33 5/8"
ours: 39 1/4" x 25".... New: 40 7/8" x 25 5/8"

So here's the question: How difficult would you expect installing these new windows might be? Would it be easier to install the smaller windows or the larger windows?

We're reasonably skilled (redoing closet shelving, doing trim work), but have never modified wall studs or installed a window before. I watched several youtube videos showing window installation, but none showed the scenario where the new window was a slightly larger size than the original. I'm getting DIY'er cold feet! Other than electrical and plumbing, my other major DIY fear is messing up something on the exterior of the home and causing water damage.....

Thanks for yor help!

rjniles 09-11-2010 10:52 PM

The dimensions that you say are the existing windows, are those the size of the windows or the size of the rough openings? If those are rough opening sizes, it will be a huge job to increase the size of the openings. I would order custom made windows or try to find another manufacturer that has a better size match. Yes custom windows will be expensive.

Just Bill 09-12-2010 06:45 AM

What he said, probably. The actual size of the window and the opening are critical. Doubtful that the new window will fit the opening, but a slim chance. To enlarge the opening, even for a couple of inches, the header must be enlarged, definitely a major job. Most companies offer custom sized widows, but for some, the cost difference might be worth altering the opening. And most windows use a nailing fin to secure it in the opening. This requires removing some siding.....something else to consider.

Scuba_Dave 09-12-2010 08:38 AM

Do they have the window in stock to measure the actual width ?
My experience has been that there is a lot of play on either side of the window
So a window that states a RO of 52 7/8 might fit into a 51 7/8" opening
That would leave 5/8" to shave off to fit
So shaving 3/8" off each jack stud would work
I might do that, depending upon the width of the window, load above etc
It is a PIA to shave off each stud

As an example...widths
2 of my Andersen windows state RO of 30 1/8, actual stated size of window 29 5/8"
actual window measured size 29 1/8"

Gary in WA 09-12-2010 10:53 AM

Please don't shave 3/8" of each jack stud to fit.

That is 1/4 or 25% weaker to hold up the same load above.

Manufacturers require 1/4" (usually) space above the window for settling of the loads above and the side space for expansion and contraction from the seasonal changes in humidity. Not keeping this space voids the warranty. The R.O. they give is for the window operating properly and the warranty.

I agree, easier to go smaller, just tell them it's for egress on one window. Most sidings are easy, if not time consuming, to fix, with drywall being fairly easy.


diy'er on LI 09-12-2010 02:42 PM

sorry... let me clarify the dimensions....
When I measured the old windows, I pulled off the trim and measured the actual frame. Similarly, the new window dimensions represent the frame, not the rough opening.

The old windows were original to the house... so the drywall is precisely cut around these windows. There is less than 1/8" between the window frame and the drywall. I have no idea what the studs / framing looks like beneath the drywall.

OK, as a DIY'er, I always try to find the path of least resistance. So I think I'll go on anderson's website, confirm that there is nothing closer in size, and then I'll parouse other brands. The last thing I want is a big ol' framing mess that we don't have the skills to fix!

Thanks so much for your input...

diy'er on LI 09-12-2010 02:49 PM

oh and by the way, I'm already getting burned by this project, and the windows aren't even ordered yet! Last night I was surfing the net and watching window removal/installation videos and I managed to get not one, but TWO trojans!!! My windows defender was unknowingly uninstalled, and my antispyware programs were corrupted. I had to do some major computer stuff to backdate my system to last week, and restore everything to its former self.

So, my lesson has been learned. Use firefox with the WOT ratings when roaming on random websites. Even DIY sites can smack your system down! sigh....

Tom Struble 09-12-2010 03:17 PM

cut some of the drywall away so you can get an r.o. measurerment:huh:

Scuba_Dave 09-12-2010 04:13 PM


Originally Posted by tomstruble (Post 499986)
cut some of the drywall away so you can get an r.o. measurerment:huh: need RO measurements :thumbsup:
My old windows still had the rope & weights in the sash pockets
So I was able to install windows that were on average at least 3" wider

diy'er on LI 09-12-2010 04:25 PM

ok. We'll do that as well. I think i have to be very careful doing that with the smaller window, as I can't find the stupid paint can for that room anymore!:wallbash: (And yep, basement organization is on the winter list.......)

Tom Struble 09-12-2010 06:12 PM

well don't put in a smaller window just because you can't find the paint,thats ridicules

diy'er on LI 09-12-2010 07:59 PM

no no no... Of course I won't do that. I'll practice chipping away the drywall around the bigger window (where we're repainting), and then I'll gently chip around the smaller window to figure out the rough opening size.

i'm more optimistic of these results after Scuba_Dave's comment... I hope there's a lot more room in there than I expect....

alas, it's a new work week... tomorrow my 90 min commute begins again. That along with my toddler will probably prevent me from getting very far with this project before next weekend :(

diy'er on LI 09-18-2010 08:56 AM

OK, another work week is done...... We're prying back the drywall and investigating the rough openings right now. And Scuba_Dave is right again!!! Our rough opening is almost EXACTLY what we need. So it's a close call, but we have the 52 7/8" that we need. The vertical measurement is more forgiving... a bit larger than the rough opening we require. The small bathroom rough opening is also larger.

I'm so relieved!
We did discover another big ol' mess. When we removed the drywall, we can see directly to the outside!!! What the heck?! We have shingles out there that partially covers the hole, but no insulation, and obviously, no tar paper or waterproofing. NO WONDER that room always seemed damper than the rest of the house.... I hope that doesn't turn into another big issue. I'll have to research how to properly water proof (add tar paper and other moisture barriers and feed it under the shingles and over the exterior tar paper. Good grief. I'm glad we dug in there before we took out the window! Thanks for your help,

rjniles 09-18-2010 09:09 AM

Since most new construction windows come with a nailing flange that is installed under the siding material, I would remove the shingles to insulate and water proof the wall properly.

And if that room has no insulation, I suspect the whole house may be the same.

luvdairish 09-18-2010 06:43 PM

Depending on the local code, you could more easily add a taller window by cutting the studs below the window and leaving header intact. That might open up some other sizings for you. Additional width would be significantly more difficult (i.e building a temp wall and replacing header and some adjacent studs), but wouldn't be that difficult if you thought things through. If money isn't tight, get the custom size. Just remember if you are going to expand width you will need to remove some siding and cut back the plywood sheathing as well. I'm a DIY'er and made similiar mods just recently. It can be overwhelming at some moments, but very rewarding in the end.

Hope that doesn't make your decision more difficult. There is plenty of experience in this forum to help you along with anything you do! These guys are great :thumbsup:

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