ralphfravel

I am replacing my existing stairs from the entry to second level in a split-level home. I plan to preserve the overall dimensions (rise 7.6", tread 10.3") since they work well and meet IRC code. However, I plan to change the design so that all treads are open on the both sides with 2 balusters per tread. Length of each tread will be a 47". I have two questions:

1. How many stringers do I need? I've read on other posts to use one stringer per 12" but this works out to 5 stringers which seems (gut check) to be too many.

2. I've read in a Taunton Press book about stairs that stringers made from glued-up 3/4" plywood are the best way to avoid squeaks and other problems due to shrinkage. Has anyone tried this method and/or does anyone have suggestions for stringer material?

Thanks in advance for your thoughts.

NailedIt

I build stairs with at least (3) stringers minimum, and the 12" tread-width per stringer is what I use. Generally speaking I don't use plywood for stringers unless the builder/homeowner/designer requests that I do so. But... plywood is considered dimensionally stable as opposed to solid dimensional lumber, such as a 2x12. Shrinkage in the dimensional lumber may cause some squeaks. This is usually mitigated/minimized by glue(PL400 or eq.) between the treads/risers and the stringer and by using screws vs. nails in assembling the stairs. I'd use 1" or thicker plywood if you go that way. You could use PSL for stringers if you have a span longer than 8'.


2x12 are usually adequate in a single-family residence.

ralphfravel

Thanks for your reply NailedIt. After more looking into available materials, I decided to go with four 1.25" x 11 7/8" TimberStrand stringers. For me this was the best tradeoff of my time, money and need to avoid squeaks in the future.

thekctermite

Short of spending big money on LVL, Timberstrand is the best material for stair stringers in my opinion. Timberstrand rim board is listed for use as stringers, where most other brands of engineered rim board are not. I think you're wise not to try to use plywood.

__________________
The building code is a minimum standard, and merely meeting it instead of exceeding it equates to building your project to the worst standard that the law will allow.

ralphfravel

Thanks for the affirmation TKCT. I'll let you know how it turns out.