I am rebuilding the stairs off my deck in the backyard. If I used 7" risers it would create some space problems with the total run ( although if push came to shove I could do it). I wanted to use 8" risers so as to decrease the total run. I know the general rule for 7" risers is 11" tread, but what would the tread be for 8" risers?
Intersting to note that on the osha website the table does not list the "7-11" rule. It shows for 7" risers to use 10 1/2" tread. And for 6
1/2" riser use 11" tread.
The general rule is that the tread + the rise should be between 17 and 18. For example, an 11" tread plus a 7" rise equals 18. It's a ratio that will provide a comfortable "feel" to the stairs regardless of their pitch.
For an 8" rise, you would want something between a 9" and 10" tread. Go for the wider tread if you have the room.
Note that the tread width does not include any "nosing" on the tread. This can extend about an inch beyond the tread width. So, for a stair carriage cut with 10" treads, you might have a step that is actually 11" deep.
Anthony
11 inches.
You should check you local building codes.
Rule of 17 would indicate 9" treads. Rule of 18 would indicate 10" treads.
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I think 10" treads are the minimum currently allowed.
Don't think 8" risers are allowed any more either. Seem to recall 7 or 7.5 as the max.
Of course your area could vary either way.
Colbyt
Thanks for everyones responses. After thinking about this for 2 days, I am going to play it safe and go with 7" risers. The only thing is I have to move some shrubs out of the way due to the overall longer run, but not a big deal.
This got me curious so I just measured my steps 7 1/2" rise and 9 1/2" run
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