stringer 2x10?

[MarkAndDebbie]

We have been eaking out the last bit of headroom under our open riser stairs (still working on the sketchup). We are doing a 7.75 risers with a  9" tread (it's a modification in our code - IRC is 10" min tread). We'll do 2 treads - then a landing - then 10 more treads. So the long stringer will span 10 x 9" = 90".

THe question is can I use 2x10's instead of 2x12's for the stringers? Should I use more stringers? 3? 4?

Let me know if you need more detail.

Thanks!

[PEG688]

Use 2 x12's , we space them no more than 12" apart and use 2 by tread material , YMMV.

[MarkAndDebbie]

Use 2 x12's , we space them no more than 12" apart and use 2 by tread material , YMMV.

In the loft we're spanning almost 4' with 2x6 t&g, but here we don't even go the 18" to the edge of a 36" stair? Is there something more than the deflection working in the center of the stair? (This is actually what I was thinking when I asked if I could go to 2x10 - add another stringer to take some of the load.)

So PEG. How about 4 2x10s

Also, would it help to not notch them? Something more like this

[PEG688]

One thing that is for sure there's ALWAYS another way . I'd call that a ladder not a stair system.  

Spanning 3' with a single 2x6  or even 2 x12 is two far IMO . Stairs can and do get big loads placed on then , furinture , appliances , groups of people passing , etc .

So IT DEPENDS on conditions not in evidence / presented / admitted to / revealed.

I answer questions based on what is "normally done " , there are exceptions and wide / strange / odd / and just wrong that people do every day . I can't cover all those variables in a short answer , given 1/2 or sometimes less , of all conditions .    

[MarkAndDebbie]

That one is definitely a ladder.


I wasn't complaining PEG. You did a good job answering my question. I was just reaching/grasping Trying to understand the forces at work.

[Ernest T. Bass]

2x10s would be fine as long as you don't notch them.. Perhaps you could beef up the treads to make the 3' span without a third stringer? Maybe you could go for more of a timber staircase.. 4x10 stringers and 3'' or 4'' treads or something like that.

[PEG688]

Yes a timber stair could work , either with the bracket shown in your photo , or a trapped tread routed into the stringers . Heres  a recent thread from Wooden Boat Forum  on stairs like that.  

 http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=66459