Innies or outies?
I’m struggling to decide between “innies” and “outties”, have nice 12 over 12 colonial traditional wooden windows, no nailing flange, i have completely restored and looking to install in a barn frame i have moved and reassembled. dreams of one day becoming a home. labor of love. progress is decided on what sort of craigslist or reclaimed deal i stumble upon, and plans have altered once again with stumbling up a great deal on 1″ XPS rigid foam.
Currently i have 2×6 framing with Zip sheathing. i now plan to wrap that in two layers of 1″ XPS (R10) meeting the climate zone 5 external insulation minimum or R 7.5. i would like to incorporate my true 1″ furring strips in the second layer of 1″ foam as to not build out the wall further than i need to; synthetic slate roof (another craigslist score) is already on and my overhangs can not be altered. over that i will have rain-slicker rain screen mesh and then my siding.
With only two inches of external rigid foam, and another 1″ of siding and rain screen, the finish siding will only be 3″ off the sheathing. so now to the question:
If i was to install my windows as “innies” and then box them with 1×4 PVC trim it leaves me a 1/2 ” reveal past my siding on this “exterior jamb extension” and then 2 1/2″ off my original window trim/brick-mold. it kind of adds another depth feature to all the trim which i don’t mind while the other part of me thinks its not the traditional look.
If i was to install as “outtie’ windows my thought was to picture frame the RO with a layer of 1″ ZIP R (1/2 zip osb, 1/2 rigid foam) on top of that would be 2X4 on the flat, padding me out 2 1/2″ off the sheathing and allowing me to then install windows at that plane. all stacks up to traditional installation and reveal with siding.
Does having thew windows in 2” really help with efficiency and longevity? again wooden windows traditionally putty glazing. would be nice to protect a tiny bit more for longevity. does it really just come down to appearance and aesthetics?
Any opinions or experience would be great, i’ve read almost all the articles and threads, oh and its pretty much going to be me on this project and theres about 50 windows! LABOR OF LOVE! HELP
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Replies
If it works with the look of your house, I prefer outtie windows. I find the deeper jambs make the windows look more substantial and the deeper window sill is great for plants.
Mostly the decision comes down to what look works best for you. Getting the window to last is more to do with getting the flashing details right than window location.
Absolutely innies. A window is warmest when 30-60% within the wall. Lots of science behind that.
Since you have one vote each for innies and outies, I’d like to offer a third option: an “in betweenie”. If you set the window partly into the wall with respect from the exterior, so it’s not really and outie, you can get much of the benefit of an innie (better insulation) with much of the benefit of an outie (better light gathering, and some people prefer the exterior appearance of an outie).
You have a lot of flexibility with the exact placement as long as you’re careful with your flashing to make sure you don’t have water ingress problems. You might want to check out the thermalbuck product too.
Bill
30-60% is still considered an innie because you still have to do some fine jam work around. Usually using a window buck for support.
The best way to shelter wood windows is to reduce the wetting events they "see." Pull these windows in as much as you can.
Peter
The Passive House Intro course I took recommended "in-betweenie" window location, as they show less heat loss around the window perimeter. Outie allows coldest part of the wall to be near the interior side of the window. Innie allows cold air farther into the building envelope, nearer the interior of the home. So they argue to avoid these two issues and install windows "in-betweenie" to minimize heat losses around the perimeter of the window (and show nice color graphics of temperature across the wall and window, which unfortunately I can't find to post here).
Personally I prefer either outie (deep interior window sills are preferred by most people) or "in-betweenie". You can have insulated and/or protective exterior shutters that will close into the exterior of the window indentation with "in-betweenie" windows. Without shutters, "in-betweenie" windows would provide some protection from the elements that Peter noted, just not as much as innies.
These windows are flush with the Zip sheathing and sit about 6 inches from both the exterior and interior casing so I would call them "in-betweenies." We still need to add shutters. I like the added depth and shadow lines that you get on the exterior with this placement and I am not a fan of the extra deep interior jambs and sills you get with outie windows when you have thick walls. From an air sealing, water management perspective, it is much easier to tape the exterior face of the window to the sheathing when they are on the same plane. I spent a lot of time in a boom lift taping windows and I am glad I did not have make any inside corners, bow-ties or alligator cuts out of sticky tape on those hot summer days. For the inside face, I was able to pre-tape most of the doors and windows using both Pro-Clima's and Siga's double-sided tapes. You need to make "rabbit ears" in the corners so that you have the extra slack needed to reach the rough opening. Eliminates the need to make inside corners.
I appreciate the replies and am trying to figure out a plan for the “inbetweenie” approach. Been drawing some stuff up and figuring out flashing plans, about to just cut a whole in the sheathing and see what looks beams and makes the most sense. Thanks for the feedback.
That looks great. Beautifully detailed. I agree with you and Michael that an exterior real really adds something to a house.
Modern windows sit too flush to the siding, creating a flat, planar look. Traditional homes had shadow lines that provided character to the exterior. At minimum, I would put the face of the window in line with your sheathing, which also makes it easy to continue your WRB and airtight layer, if those are at the sheathing layer as well.
I can't let a mention of XPS go by without asking why you don't use polyiso instead. The blowing agents in XPS are potent global warming gasses, 1400 times worse than CO2, and over the course of a few years the foam degrades to about R-4.2 to 4.4 per inch. Even derating polyiso for its lower performance in cold weather, it still outperforms XPS, and its blowing agents are much more benign.
Like I said the progress is decided by craigslist deals and when you come across 250 sheets of 1” XPS for more than 80% off it allows me to move forward. So XPS it is.
I understand the blowing agent concerns and I think I’ve made up for it in the R58 I was able to build up in the roof, completely reclaimed. And about 80% of it was free.
Again restoring old windows......50 of them rather than just buying new. I’m trying to do my part.
Thank you for all of the feedback, I really appreciate it. Nice to have some other thoughts coming in from the outside and not just my own brain turning on itself over and over.
Here’s the windows, over 550 panes off glass removed, frames restored and painted and glass reinstalled. About 50 windows total, frames completely built from scratch, only original sashes were salvaged not the frames too...bummer. Oh so I also couldn’t afford any sort of decent lumber and figured if I was putting my time into these I didn’t want just pine, so the sills are from someone’s reclaimed mahogany deck.
But I’ve got more hours into these and this project than you can imaging and it’s going to be quite something to look back on.
My labor of love!
Chris,
What a great project! Well done so far - and good luck!
one more question: would it make a difference which layer of foam i incorporate my furring strips in? have 2 1" layers going on and was planning on putting them over 1st layer and then filling between with the second layer, again don't want to put them outside both layers as i'm a bit restricted on eave overhang. of course this would only leave me with R5 behind my 1x3 furring strips in a climate zone 5 ( calls for R7.5) but i think it should be fine if its just behind the furring strips. or would it be better to have the furring incorporated in the first layer and have a complete exterior layer of foam and then just longer fasteners for siding of course.
any thoughts or does it not make a difference. figured on 2nd layer i would be able to see them when fastening siding and make for easier instillation.
thanks