What is the minimum allowable elevation change in floor level? A good friend is adding on to his cape cod. He has an un finished second floor now, and plans on finishing it once the addition is complete. Currently the floor joists for the second floor are 2×6@ 16″ o.c. They are small, but the spans are short. 11′ maximum. In order to get approval for living space above the addition, he needs to use atleast a 9.5″ I joist. In an effort to keep the floor level on second story, he wants to step it down into the new addition on the first floor. Going from a 2×6 to a 9.5″ I joist translates to a 4″ drop. Would this be considered a tripping hazard? The step down would be at a door way if that makes a difference. the only other thing I could suggest to him would be to use 11.875″ I joists which would make the step 6.375″ Still low, but not as bad. He doesn’t want to get into dropping the floor down below an 8′ ceiling either. Would the 4″ drop be a mistake? I can’t find much on it as far as IRC. Everything I’ve found deals with maximum riser height.
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I don't understand this part;
translates to a 4" drop. which would make the step 6.375" Still low, but not as bad.
How is a 6" drop not as bad as a 4" drop? Anyway, it becomes a step, which I would prefer oveer a 1' or 2' drop, which might not be seen when walking. As far as being in a doorway, I would extend it like a small landing.
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
I was having a hard time trying to explain it. If he uses a 9.5" TJI, the ceiling would drop 4" becasue te existing joists are 2x6. Thats the 4" difference. So to keep the ceiling height 8', he plans on dropping the floor as well. I kinda think a 4" step would be a tripping hazard, but I could be wrong. The other option is to use 11.875" TJI's. The difference between the 2x6 and the 11.875 TJI's is 6.375". Again, dropping the floor down to match this would be a 6.375" step. He would rather not use the oversized TJI's since it would be a waste of money, but if thats the only option, than thats what it will be I guess. I also suggested making the ceiling 9' in the addition essentially dropping the floor another foot making it a 1'-4" difference. that woudl be great to have (2) 8" steps, but he would be cutting a foot off of a couple hundred 2x4's.
order 9' studs from the buuilding supply. Shouldn't be a problem if you need several hundred."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
It's an option I guess. I'll run it past him. No idea on the minimum riser height though huh? Even if just for future reference?
I'm a little confused as to all the ceiling/floor heights, but I think there could be a problem with the step being at a door. You might be required to have a landing. Check the IRC or whatever codes you are under.
I would MUCH rather have a change in ceiling heights than a change in floor elevations
Maybe this will help
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For my little 2 cents worth I think two steps is less of a 'trip hazard' than one step. Yes it's giving up quite a bit of floor space but I'm sure people are more apt to notice two steps and act accordingly, than take the tumble over one step they didn't see.Let's not confuse the issue with facts!
Ok, a picture is worth 100 words. Why do you need to maintain the floor level in the attic? Looks like that space is not really useable due to the slope of the roof. I would think you would want to keep the lower floors even."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
What is the span on the TJI's?I'm no engineer, but possibly it could be spec'd for 1-3/4 x 7 lvl's 12'' o.c.. and make the downstairs 7'-11''.
Best place to ask, will be your local AHJ (Authority Having Jurisdiction), as they are the group that "tells" the BI what "passes."
From the top of my head, all sets of steps are supposed to be even, and also fit the stairs table your locally enacted Code requires. Now, if you have a "landing," then, that specific area might could have a different rise than adjacent stairs.
Or, the BI might up and redtag it without looking. That's why asking the AHJ is good.
After all, for ordinary egress/accessibilty, anything over a 1/4" is a "trip hazard."
Hmm, depending on what the AHJ uses, to have a "landing" that would not be under the stair table, it probably needs to be bigger than the width of the stair treads in at least one dimension. Please remember, I'm making a WAG here. But, for, oh, 38" wide treads, I'd guess you'd need a "landing" that was at least 38" x 44"; then some other riser dimension would be "good."
But, that's a clean guess.