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Community and Q&A

Window sizes and shapes?

user-1137156 | Posted in General Questions on

Is there any rhyme or reason to window sizes and shapes? I know that bedrooms have minimum width, and area along with a maximum height above floor level for egress but other than those requirements what determines how many and how big? For “day-lighting” what ratio of window area to room area is minimum or recommended? Reason I ask: I’d like to minimize the window area on the North, East and West while maximizing South facing windows which will have appropriate overhangs.

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  1. GBA Editor
    Martin Holladay | | #1

    This is an aesthetic or design issue. If you feel lost, an architect will be able to help you. If you want to learn more about the topic so that you can become a better designer, my advice is to visit a lot of houses, and to pay close attention to window sizes, especially in rooms that seem pleasing to you. Be a careful observer.

  2. faaast | | #2


    One thing we found out during our custom house project was, the sizes of the windows we had on the blue prints were way too out of proportions than what was desired by us.

    Fortunately we couldn't order our windows until the framing was started in the basement and soon we realized the windows were not only positioned wrong but their sizes were inappropriate too.

    I guess since windows are usually the first thing ordered during a house build, that's why I see many people not happy with their positions or wish they were of different sizes

    also remember, too much sun on the front door, windows and garage doors could really cause a lot beating on them, so be prepared.

    Hope that helps a little bit

  3. user-1072251 | | #3

    Also depends on views & directions & what is available from the manufacturer. So if you have a close up view of a neighbor's wall, you might use high windows which bring in light, but not views. Where you have views, install windows that will capture those views - either wide windows or multiple narrow windows. Some windows are made to order; some are less expensive when you use standard sizes. You might want windows on two sides for cross ventilation. Lots of considerations for each space.

  4. Expert Member
    Dana Dorsett | | #4

    Code requires operable windows at a minimum of 8% of the floor area of any habitable room, with a operable minimum opening of 4% of the room's floor area for ventilation (with a laundry-list of allowable exceptions):

  5. user-1137156 | | #5

    Thank you for the code reference! To me the exceptions say that operable windows,other than required for egress, are only required in houses with more than 5ACH @50PA (whole house mechanical ventilation is required for ALL with less leakage, R303.4). And with modest artificial lighting ANY glazing is optional.

  6. user-4524083 | | #6

    Jerry - Some "rules of thumb"( not accepted by all) in a tight well insulated house using high SHGC low-E double glazing on the south : shoot for 50% of your glazing to be south facing, if you like sunny, with 8-12% of the floor area of the house in south windows. More mass in the house can tolerate the upper range without overheating. All the numbers change with triple glazing. If you know the placement of the house, you can try to visualize the view you'll get with specific placement, but ideally the house should be built slowly, so that you can make changes as it takes shape. Ordering windows from Lithuania makes this last part difficult. Good luck !

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