In betweenies: flanged or not?
I am about to order some windows to install in a double stud wall, planning to use the ‘in-betweenie’ install method.
My question is, if given the choice, is it better to get flanged or unflanged windows. I’ve seen details for both (mostly details for flanged windows here, but seen some unflanged on 475).
I have never done this sort of install, so i’m not familiar with the intricacies. It would appear that the flanged windows requiring another ring of 2x material inside the buck would have slightly worse thermal performance (even with back insulation, it would be less than the wall R). But will the flashing be easier with flanged perhaps?
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Oh, which reminded me. I already have one window that i pulled from another site and it is a replacement window. It seems to me that in this type of install it should fair quite well using the non-flanged detail. Anyone used replacements in this way?
Tyler,
As you know, you can do it either way. In case you haven't seen it, you may be interested in this article that describes how to flash in-betweenies when the windows have flanges:
Windows in Double-Stud Walls: In-Betweenies
I find it easier to use flangeless windows for inset windows, but when designing for others I ask the contractor if they have a preference. They nearly always do. Either way can work just fine. With flanged windows you do need the extra layer of 2x material, but that can be helpful with flangeless windows too, depending on the situation. When using European-style windows it's always a good idea to use "over-insulation," meaning insulation that covers as much of the frame exterior as possible. When you have an extra 2x buck, it just means that you need a bit more over-insulation.
thanks for the replies. Gathering that it is largely builder preference without one being a clear winner from an energy and water management standpoint.
unflanged are way easier and cheaper. Most high-end European windows aint got flanges. Why, cuz you cant waterproof a window, but you can easily shed water off a structure (rough opening).
check this out:
https://www.greenbuildingadvisor.com/community/forum/green-building-techniques/46626/non-flanged-insert-window-replacement-flashing