Stair stringer questions

I built a 2 story 3 season room attached to basement and upper story of my bilevel house last year. Tore some miniscus cartilage, so finishing inside now. Wife changed what he wants for stairs, so tearing out temp stringers and temp boards on stairs soon. That said:

I've made stair treads of hardwood 1 1/16" thick, and risers 1/2" thick to go on new stringers, when I make them. I will be adding 1/2" plywood as base under the hardwood stair treads. Will cut risers and treads to fit once stringers are in place.

Stairs are in two sections with a landing between, all meet code here. Total rise is 54.5" for each section, and total run is 66". When figuring for stringers, do i need to take into consideration the thickness of the 1/2" plywood base under the treads, the treads for the stringers. I've only done deck stringers, so this is new to me. maybe I'm making more of this than I need to.

I'm guessing I need to figure .5" base tread + 1.0625" (1 1/16") tread thickness into equation. If I do, then i come up with 6 steps, 7 risers, 11" tread minus .5" for riser thickness. Now to remember how to cut the stringers again. Not something i do every day, but will work out.

Thanks Again to all of your help.
drammen

 

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I don't see the need in the plywood under the treads, and you didn't stipulate one. If for strength, add a stringer to the middle. The plywood may throw off your rise, which will be about 7 3/8" consistent.

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