Code question: How much window, exposure to natural light, is required in a full basment? A percentage of basement square footage?
Thanks!
Tachi
tachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
Code question: How much window, exposure to natural light, is required in a full basment? A percentage of basement square footage?
Thanks!
Tachi
tachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
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Replies
Hello Tachi:
You plan to use the basement as living space, utility space, or just for the mechanicals?
Hmmm.... good questions. Certainly for utilities and mechanicals. Eventually, I will probably add some living spaces, but not initially. It will also be used as a work space for hobby and shop. Does that answer the question well enough? I assume that I also will be required to have a bathroom there, as well. It will also have an outside access stairwell with an exterior door at the bottom of the steps.
Regards,
Tachitachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
Tachi:
(disclaimer up front -- local codes vary so check with your building inspector). If you use the basement as living space ("habitable space") you have to meet the general building codes. A common requirement is that every room have at least 8% to 10% of its square footage as window area (depends on the code). If the windows are below grade, you need to have a clear area (window well or area way) extending from the bottom of the window at an angle no steeper than 45 degrees to grade. Some codes also require a minimum window clear area, even if a room is not a sleeping room (3.3 sq. ft. clear area, 20" x 24" opening minimums, for example -- depends on code) to provide for egress and fire fighter access in the event of a fire.
Here's an example from the Philadelphia Property Maintenance Code (applicable where I am to even existing buildings -- not just new construction or rennovation).
PM-402.1 Habitable spaces: Every habitable space except kitchens shall have at least one window or skylight of approved size facing directly to the outdoors.
PM-402.1.3 Window area: The minimum total window area of every sleeping room with 100 square feet (9.29 m2) or less of floor area shall be eight percent of the floor area. The minimum total window of every sleeping room with more than 100 square feet (9.29 m2) of floor area shall be eight square feet plus five percent of each square foot of floor area over 100 square feet (9.29 m2). The minimum total window area of every other habitable room for which windows are required shall be seven percent of the floor area.PM-402.1.2 Basement habitable spaces: The required window area serving habitable spaces in basements shall have a minimum outside horizontal clear space measured perpendicular to the window, equal to one and one-half times the depth of the window sill below average adjoining grade.
Here's an example of IRC requirements:
Minimum window area shall equal not less than 8% of the floor area of the habitable room.Basements with habitable space and every sleeping room shall have an exterior door or a window that meets the following: finished sill height within 44" of the floor, minimum net clear openable area of 5.7 square feet. Minimum width of opening is 20" and minimum height of opening is 24". Grade floor openings may have a minimum net clear opening of 5 square feet. R310. (Grade is defined as windowsill opening not being more than 44" above or below the adjacent finished ground surface.)
PS: any relation to Tachi Y. of GSK fame?
Thank you for the detailed response! That really helps. Now, I will have to look for the local variations, as you suggest.
No relation. Tachi is a nickname that I have had for over 30 years. Believe it or not, comes from Poland. My wife's parents were holocaust survivors. Her Mother's Father was known as Tatashi, which got shortened to Tachi. And my kids stuck that moniker on me, which was picked up by friends and business relations. Now, working in Asia most of the time, it has helped, because most Asian languages struggle with a name like Todd.
Regards,Tachitachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
BTW, I have heard that some communities are requiring a 2nd exit (egress windows or wallout basement) from all basements on new homes, no matter what the plans are for that space.They assume that at some time part of it will be finished.
Yes, that is the case with the area where I am planning to build. The plans do include a set of external stairs from the basement, and an exterior, secured door. But for security reasons, I did not want to put a window in that door. But maybe I will put a single light near the top, just for natural illumination.
Regards,
Tachitachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!
while you may not plan on using the space as a living/residential space, if something happens, you still need to get out, so it's in your own best interest to have the egress windows and the other code requirements needed for an "occupied" space
I hear that, and it makes sense. I would just rather not have 10 sq meters of window on every space. It does mess with security, and with the opportunity for moisture problems. So, I will ensure that I have large overhangs on the roof line, which I prefer, anyway, and make sure that the window bucks have a pipe down to the foundation drainage line. Then try to put such windows in strategic locations, etc.
Thanks.Tachitachi
Family in Tucson, business in the Far East, and heart in the Colorado mountains!