# octagonal stairs



## loneframer (Feb 13, 2009)

basswood said:


> Don't need no stinkin' risers... or stringers:


 That's pretty, but where do they keep the wine?


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## ClemS (May 4, 2009)

i'd provide adequate bolting supports top and bottom. use an lvl for the stringer. cut the stringer in without doing any other work. bolt a 1/2" steel plate to the inside of the stringer following the exact pieces you made out of wood. weld the compound miters together. 
set the platforms using steel c-channel back to the outside wall, front and back of the platform. bolted to stringer and exterior wall. bolts your composite stringer top and bottom. fill in the pieces and make pretty.

don't use granite for treads and you're in the clear.:thumbsup:


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## Cache (Sep 18, 2007)

ClemS said:


> i'd provide adequate bolting supports top and bottom. use an lvl for the stringer. cut the stringer in without doing any other work. bolt a 1/2" steel plate to the inside of the stringer following the exact pieces you made out of wood. weld the compound miters together.
> set the platforms using steel c-channel back to the outside wall, front and back of the platform. bolted to stringer and exterior wall. bolts your composite stringer top and bottom. fill in the pieces and make pretty.
> 
> don't use granite for treads and you're in the clear.:thumbsup:


Could you provide a bit more detail on how you would use the c-channel for the platforms? Can't visualize how you are suggesting to bolt the channel to the stringer and wall?? I'm probably just being stupid right now. thanks


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## ClemS (May 4, 2009)

Cache said:


> Could you provide a bit more detail on how you would use the c-channel for the platforms? Can't visualize how you are suggesting to bolt the channel to the stringer and wall?? I'm probably just being stupid right now. thanks


c-channel in lieu of the platform riser and back. you can make a welded or a bolted connection to the steel plate @ the stringer. 
bolting to the wall is a little trickier because your platform riser and back are the corners of the octagon. you don't want to just lag bolt something into the corner because lags will wear out. you need to through-bolt through the corner post. how this gets done depends on circumstances and layout. 
sometimes there's zero room to get in that first bay because of a window or just a stud that you don't want to touch, so it may get hairy. 
if you can hack up the wall to your liking then it's really no big deal to leaf the end of the c-channel to slide into a kerf in the wall, and then through bolt. 

there are other way to make a positive connection at the wall, but it's hard to gauge the appropriate way without some pictures.


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## Scribbles (Mar 10, 2009)

basswood said:


> Don't need no stinkin' risers... or stringers:


that nice of a stair ya think ya could blend out the pitch change.


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## Cache (Sep 18, 2007)

ClemS said:


> i'd provide adequate bolting supports top and bottom. use an lvl for the stringer. cut the stringer in without doing any other work. bolt a 1/2" steel plate to the inside of the stringer following the exact pieces you made out of wood. weld the compound miters together.
> set the platforms using steel c-channel back to the outside wall, front and back of the platform. bolted to stringer and exterior wall. bolts your composite stringer top and bottom. fill in the pieces and make pretty.
> 
> don't use granite for treads and you're in the clear.:thumbsup:


This is pretty much exactly what we ended up with. Consulted with two engineers about it and neither knew how to accomplish it. I drew the cad detail and delivered it to one of them as well as my steel guy. After viewing the CAD, the engineer still had to review it about five times before he understood what I was asking for. He kept wanting to spec out a the entire stair framing in steel. In the end he changed the material of the beam that the top stringer attaches to from LVL to 10x2 steel tube and stamped it. Headache gone for now, until I actually have to crane this thing into place and hope it fits.


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