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Ordering the Right Size Windows to Minimize Waste

drewintoledo | Posted in Green Building Techniques on

I’m not a builder so I have limited knowledge of building practices.
I will order my windows soon and my question revolves around the width size of windows.
Does it make sense to order window widths in intervals of stud spacing?   For example, a window measuring 110.5″ wide would fit exactly between studs, right?  Would it help when installing standard insulation batts?  Would that minimize the number of kind/jack studs?
I’d like to learn the “magic numbers” if they exist and will alter the size of my windows if it will create less waste and increase efficiency.

Thank you

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  1. Patrick_OSullivan | | #1

    > Does it make sense to order window widths in intervals of stud spacing?

    Not necessarily. Architectural elements and symmetry are usually more of the controlling elements with regards to window sizing and placement.

    > For example, a window measuring 110.5″ wide would fit exactly between studs, right?

    Sure, but how can you assure your studs are aligned such that stud layout aligns with where you want the window to be? Framers are in control of stud layout, and they will usually set layout based on what makes more sense to production, not based on your window layout. What this means is that if your window placing doesn't align with how they want to set layout, you're going to end up with extra studs in the wall even if the window RO is the "right" size.

    > Would it help when installing standard insulation batts?

    Insulation contractors are used to dealing with different size bays. It's not a concern at all.

    > Would that minimize the number of kind/jack studs?

    Maybe. What is more effective at minimizing wood is applying some advanced framing techniques:

    - 24" OC stud spacing
    - No headers in non-load bearing walls
    - No end cripples under window sills
    - Two stud corners with scrap wood for drywall nailing on the 'non-stud' inside corner.

    Houses should look nice. Let that dictate your window sizing, not how they fit between studs.

  2. Expert Member


    Patrick gave good advice - you will remember the dozen studs you might have saved every time you try and look out a window that misses part of the view you wanted, or sits lopsidedly in a room.

    Where it occasionally does make sense to think about that is when dimensioning things like decks, or wall lengths. A 8'-4" wide deck eats up a lot more lumber and decking than a 7'-11" one. Same with an 8'-4" long exterior wall that will be sheathed.

  3. drewintoledo | | #3

    I get it, and I should have mentioned that I’m aware of the architectural penalty. My plans allow for a little give and take on the largest holes in my southern exposed wall so I thought it might make sense to move the width a few inches either way.
    It sounds like to really doesn’t matter what size the window is. Ie; Any size would create the same amount of material consumption as another.
    Now youve got me thinking about sheathing, but that’s a dimension I have no wiggle room on!

  4. walta100 | | #4

    Do you have a set of plans yet?

    Window size and placement are key Architectural choices made very early in the planning stages.

    The very best windows make lousy walls and window are very likely to be the largest single non labor budget item. The best windows R value is quarter of a code minimum wall and cost 10X the wall per square inch.

    From a green and budget points of view few and smaller windows are the way to go.


    1. drewintoledo | | #5

      Yes sir. I just replied to an older thread.
      I agree with you, I won’t settle for anything less than PHIUS certified windows.
      Been planning for a couple years... looks like it might happen in the next couple of months.

      1. walta100 | | #7

        “I won’t settle for anything less than PHIUS certified windows.”

        From a dollars and cents point of view I think you have been drinking the wrong Cool Aid.

        I am sure the PHIUS certified stuff is great but in most climates given today’s energy costs there is zero chance they can save enough energy cost to pay for their very high cost.

        I say ditch the one size fits all dictatorial programs. Design a home optimized using BEopt for your location your energy costs your interest rates using your guess at inflation.

        Build the right house for you.


  5. creativedestruction | | #6

    There are optimum sizes that affect glass thickness. The rule of thumb I've often heard for residential window units is 9 SF max for 3/32" and 25 SF for 1/8" and beyond that they need tempering, otherwise thicker glass may require non-standard frame profiles. There's engineering nuance behind all that I imagine, and variance by manufacturer. If the lesser dimension is over 5 feet the number of available manufacturers diminishes. I've heard imported high performance units only use 1/8" (3mm) plus so the smaller units don't save anything on thickness.

    Don't forget about egress requirements for bedroom windows. And shim space of course -- frames need to be smaller than rough openings. Yes, I have seen folks miss that.

  6. Mark_Nagel | | #8

    Most (all?) window manufacturers will have installation dimensioning info. Need to account for all barriers/seals and sill plate materials in determining rough cut size.

    Not only is there viewing angles and aesthetics from the inside of the building, but also from the outside (though viewing angles would/could be a lesser concern).

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