Building Homes or Extensions/Calculating Stairs


QUESTION: Hi, Im trying to help someone to put in stairs from one landing to the next. The rise is 50 inches from one landing to the next. Ive tried using the calculators but the area is only 40 inches across. It keeps saying a 60 inch run which I dont have. I hope this is making sense. I know as a rule treads should be 10 inches(min) Im thinking the risers could be shorter? Its an older home and there is really no where to go sideways. Thanks for your advice.

ANSWER: Hi mike, per most building codes your risers should max out at 8-81/2".  If your overall rise is 50" then this would require six risers of 8 11/32" and with your 40" run five treads of 8".  Which is not too bad, two risers plus one tread should be somewhere around 24-25".  It's not the best step in the world and you might try leaving the risers open and using a 2x10 tread (91/2") with an inch and a half overhang on your stringers.  Which means your bottom tread will stick into the room 1 1/2" which  you might be able to live with.  Don't forget that when making your stringers your bottom riser will be minus the thickness of your tread material so that when the treads are in place the risers will all be of equal height.  Sincerely Bruce Johnson

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ok if I have this right 8-81/2 for riser, is this including tread? I was under impression that code preferred a more normal rise of 7 inches. The reason I ask is what was there was a rise of 8 inches and 5/4 on top. The treads were only 6 inches which is practically impossible to walk up. I mentioned the 40 inches as that would be the run which I gather you figured. The problem is the lower landing is actually just inside this hall door. and is 45'd. I dont have an issue really with the rise but agree its not ideal Im just looking for the best way to make wider treads, even if it means leaving the risers open. Thanks for your help.Im just trying to make sure Ive digested this right before marking the 2x12 and cutting thanks

Hi again Mike, let's face it with your 40" run and 50 inch rise you are not going to  have a code compliant set of steps no matter what you do.   If you have a door right there and other issues that compounds the problem as well.  If the layout lent itself you might be able to build a corner stair which is similar to a circular stair layout with the steps tapering from wide to narrow.  I have seen attic steps with a 10" rise and an 8" tread..but they were difficult to walk on and one had to be careful.  I'm not sure of your situation, who will be using the stairs and other circumstances or possibilities..but the problem with stairs is they require a certain amount of room to work.  If you don't have the room you have to use the room you have.

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Bruce E. Johnson


I can answer any construction related question in regards to carpentry, concrete, drywall, masonry, structural elements of any type of building, residential or commercial. Interior or exterior.


Custom Commercial and residential buildings. Churches, theaters, schools and auditoriums. Most recently I am working with the Catholic Church on several design build committees. I have a website related to scheduling and project supervision. Although my expertise is more related to multimillion dollar commercial, educational and theatrical projects my generous credentials in residential and remodelling construction make me a viable source of information regarding all forms of building questions.

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