I'm off meds now, papadave, but I'll come help if I can just get outa work So, unless you can wait another month and a half
This is basically what I went through during my window & residing project. 2x4 and 1x4(which will need to be ripped as they are wider than 3.5" unless your walls are deeper than dimensional 2x4) I used all PT wood. You're going to want to consider the side-side placement if the siding is staying as the trim boards to fill the gap will be a PITA to fit unless you plan to scribe from the new window. I found the easiest way to shim the sill after foil backed rubber tape was installed was lay shims with a level and tack them with a brad set widow nail one upper corner then side shim, test operation, side shim then nail off the flange. Then you get to deal with the sheetrock void
Thanks basod. No sheetrock yet, so I can do what want inside w/o issue. The outside will be interesting though. I just need enough fill to be able to nail off the flange. Flanges are usually about 1.25", I think. Until the windows are onsite, I'm playing a numbers game hoping it'll work out. Biggest concern I have is how to make up the difference outside once I fill in the RO with a stud, and/or 1x. Couldn't I rip some 1x or OSB to flush up the exterior?
Are your walls framed with more modern 2x's or more distant past, rough sawn-closer to true 2x's? What was used for sheathing? These questions will answer how you fill in the void.
New enough that they're 1.5x3.5". Sheathing, I'm unsure about. Been thinking about tearing out some of the trim outside this weekend as it's partially rotten anyway, so I can see what we'll be working with. That way, I can get the materials needed. I don't wanna' stop in the middle of this to make a "parts run".
Sounds like a "first move" plan. If you have current nominal 2x's, I'd still keep them to the inside, and shim to the exterior.
You should be fine filling the exterior space with OSB strips be sure to measure the existing sheathing thickness most are 7/16" but if you have some older plywood sheathing it could be 1/2" Just make sure when firring out the RO that your 2x4 & 1x4 stay on the same plane as the existing studs on the exterior wall. If you end up with a bulge at a corner the window frame will toe out and the sashes won't operate properly. And make sure the framing nails are flush/countersunk they will come back to bite you with shim placement
Thanks again basod. Very good advice. I think I've got this straight in my noggin'. The sheathing is 1x12" (11.25"), but I'm pretty sure there's another "insulating" layer of a sort of fibrous stuff with a tar like coating. I'll know more when I tear into it. I would think the old window flanges should be nailed to the 1x, but with this house.....dunno. One of my biggest peaves is not having studs flush in framing. Similar to not having things plumb and square....comes back to bite ya' every next step of the process.
Of course, you could get 2x6 (or x8) and rip to total wall thickness(framing+sheathing+fibrous tar coated stuff[not tar paper?]), eliminating the other fillers.... Just a late breaking thought.....
Sounds like Cellotex or similar sheathing product. You obviously won't know the nailing flange dimension until the windows are onsite but when building out the RO to make sure the window nails aren't going to go through a seam in the framing
Heading to HD tomorrow, so I can check the flange size. What I can find re: Celotex, I don't think that's it. This is a small example of what I think is on the outside sheathing.
Papadave, 3 words to remember when installing a window. Square, Plumb and level. Make sure the window is not racked in the opening... use shims to correct it if it is. Measure the diagonals to check. With a level check to make sure the window is vertical in the opening ... even if the wall is out of plumb, again use shims to correct in or out. Then make sure the window is level horizontally. All windows today are manufactured to operate with the window installed correctly. Finally, window tape the exterior and think like water when you install the tape. Start at the bottom and overlap as you move toward the top. You could also back caulk the nailing fin to help seal the window, but that is just added insurance. Finally, any gap between the window frame and the jamb fill with insulation. If fiberglass don't put in too much and put it in loosely. use a shim to "chinck" it in. What ever you fill the opening with to make it small should work but Basod method is my method too. We have installed full frame replacement for going on 25 years so it is second nature to me. You'll do fine. If the window jamb is short of the drywall you can correct that with a jamb extension, which I can walk you through later. Get those windows in the hole Square, Plumb and level and we can coach you through the rest.
Thanks Marty. I'm not a complete rookie, and have installed a few windows using all those techniques. I've squared up cabinets using the "diagonal" method plenty of times (had a small cabinet shop with younger brother many moons ago), so I'm very familiar with all that. I've not ever had to fill an RO in an existing structure though. This is a new one for me, and I get the idea, but have no practical experience doing it. I plan to use window & door foam after install. If I can pick your brain, I bought some sealing tape that I've used before, but am wondering if there's a better alternative.......and where to get it. Sorry for the pic quality. Got it at HD. Really looking for something to use on the sill framing.
Forgot to mention that I made the run to HD today to check out the window, and of course, they've changed the window & door dept. layout. Always trying to "improve" stuff. What a PITA. The 400 series didn't have one of those pivoting samples to check the flange/fin size. I grabbed a few 2x6 in case I can use that method. I doubt my brother will be here the same day the materials arrive, so I'll have a chance to really get a good look at the Grabbed a tarp too, while I was shopping, so I can cover it all while waiting for install.