I have actually read that cut stair stringers longer than 6 feet in length call for mid-span assistance. Solid stringers seem to have the ability to gain to around 13 feet without support. So exactly how execute you integrate these 2 ideas as soon as you are structure 4 foot wide stairs and also the two outside stringers are solid and the two inside stringers are cut?

Can that span the whole size unsustained, or does the presence of the 2 cut stringers lug you ago to a maximum of 6 feet unsupported? In my situation, the complete climb will be about 8 feet or so, for stringers somewright here roughly the 13 feet mark.

You are watching: How many stringers for 48 wide stairs

Or is this ssuggest a better-safe-than-sorry thing and you just assistance it always?


It is not possible to use a solid stringer mid-treview, so where the code addresses boosted span allowance for use of solid stringers, there is a presumption that the middle stringers (if any) are cut. Your 48" width will need two reduced stringers, because anything exceeding 36" width need max stringer spacing of 18"OC. Tbelow is no assistance or expectations requirement that is dependent on stringer depth. Max expectancy 13" 3" (or 16" 6" for southerly pine). All stringers shall be minimum 2 x 12.

Your 4" wide 13" expectations stair will certainly have plenty of support via the 4 required stringers...


The Code needs a stair to be designed to 40 psf. (See ICC Table R301.1)

The net dimension of a stringer after the riser and also treview have been removed (depending on the precise climb and run) is about 5” - 5 1/2”. This is around the size of a 2x6 and a 2x6 can span around 13’ and also support about 45 psf.

As such, you need a minimum of 3 stringers (around 12” on center) plus the two external stringers extending no even more than 13’ (horizontally) to comply through the Code. (If you need to expectations further, you can usage more stringers...say 8” on center plus the two external stringers.)

The length of the stringers might be 16’ or so, however the exact horizontal dimension must not exceed 13’ to comply with the Code. The stringers have the right to be SPF and also have actually a grade of No.1 or better.


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