Building stairs question...

[Spork]

Okay... maybe "building stairs" isn't the right subject.

I'm about to start to put in flooring upstairs and on the stairs themselves.  I'm doing it with some recycled gym flooring.  My plan was to make stair treads out of glued up flooring, cut to fit and glued/nailed into place.

In looking at the rough stairs I have... I noticed the stairs are already a bit out of spec from code.*




My plan is this: 
* Remove the rough 2x6 treads on treads number 1-4 and replace with 3/4in plywood affixed with screws/PL400.
* Cover the treads with the 3/4 in treads I've made affixed with nails/PL400, giving an effective 1 1/2 in tread.

If my math is right, I'll end up with riser heights of:
1  7 3/4
2  7 3/4
3  7 1/2
4  7 1/2
5  7 3/4

My questions here:

Is this a viable plan?
Is 3/4 ply + 3/4 maple treads a sturdy enough riser

Better ideas?

*from what I can tell, code says max riser is 7 3/4 with a maximum difference of 3/8 inch between the biggest and smallest riser.  On the latter requirement, I'm already out of code.  Note here that I'm out of the city and the letter of the law doesn't matter.  There is no building code here....  however, I DO understand that code is there for a reason.  I do want to at least have stairs that are safe and comfortable to use.

The lower 7 inch riser height on the winding portion of the stairs isn't really noticeable.... since you sort of have to re-step to make the turn.  It sounds like it's a big difference, but it feels ok.

edit: fixed typo

[zolotiyeruki]

In my house, all the treads are 3/4" *pine*, so 3/4" maple by itself should be sufficient.  If you're worried about it, you can add braces underneath the treads.  In fact, I'd just go with plain 3/4" on steps 1-4, then add 1/4" of plywood to step 5, 1/2" to step 6, and 3/4" to step 7, so that you're at least a bit closer to a uniform step height.  You didn't mention what the top half of the staircase is like, but you may be able to do something similar there as well which would allow you to go 1/2", 1", and 1 1/2" on 5-7 to get even more uniformity.

[Spork]

The top end is 7 3/4 rise ... so adding 3/4 inch on each step will maintain that height.

[zolotiyeruki]

Did I misunderstand?  It sounded like the rise for each step (7 3/4, etc) included the thickness of the tread (1.5").  If you vary the thickness of the treads, you could average out the rise for each step.  I.e, you have 51.5" total rise for the first 7 steps, so you want an average of 7.25-7.5".  So use a 1.25"-thick tread on 1 (rise: 7.5), then a 1"-thick tread on 2 (rise: 7.5), a 3/4" tread on 3 (rise: 7.25), a 3/4" tread on 4 (rise: 7.5), a 1.75" tread on 5 (rise: 7.25), 2" tread on 6 (rise: 7.25), and 2.25" tread on 7 (rise: 7.25).  This puts you right at 51.5" total height, with everything in a 1/4" range.

[Spork]

Did I misunderstand?  It sounded like the rise for each step (7 3/4, etc) included the thickness of the tread (1.5").  If you vary the thickness of the treads, you could average out the rise for each step.  I.e, you have 51.5" total rise for the first 7 steps, so you want an average of 7.25-7.5".  So use a 1.25"-thick tread on 1 (rise: 7.5), then a 1"-thick tread on 2 (rise: 7.5), a 3/4" tread on 3 (rise: 7.25), a 3/4" tread on 4 (rise: 7.5), a 1.75" tread on 5 (rise: 7.25), 2" tread on 6 (rise: 7.25), and 2.25" tread on 7 (rise: 7.25).  This puts you right at 51.5" total height, with everything in a 1/4" range.

Yes, it does include the tread.

The issue here is that:
1) the rough stair is already 7 3/4 for the first step before adding treads..
2) my treads are hand made out of 3/4 inch flooring.

What you're suggesting will certainly work (and may very well be the right way to do it).  I was trying to work with the treads I have by replacing the subfloor from 2x6s with 3/4 inch ply.   I was mostly concerned with that first step being reasonable.... though maybe I *should* be concerned by the "off by more than 3/8". 

The current temporary stairs are actually pretty comfortable... I just didn't want to wreck them by adding height.

[Shop_man]

What are you planning on using for your finished flooring in that room?  Hardwood also?  Then that would subtract off 3/4" of height to that first step.  How many stringers under the stairs?  2 or 3?  If 2 then do the two layers on each tread - plywood and hardwood as you suggested.  If 3 then then each tread would only be spanning 14-18" and the hardwood alone would work.  I would keep the each step as short as possible, but realize it is hard to do in an older home.  8" steps make you feel like a billy goat climbing them. 

[zolotiyeruki]

What I meant was on the first step, remove the 2x6's, and put down a 1.25"-thick tread made of a piece of 3/4" ply layered with a piece of 1/2" ply.

[52cents]

Rather than trying to calculate this with math, put a straight edge on the wall so it touches the nosing of the treads. Ideally they should all be in line and the same distance apart. The code is there to stop you from tripping.

[paddedhat]

Many moons ago I did field measuring and design for a custom stair building company. All of the following is based on the tricks I picked up from fellow stairbuilders I worked with, and my past experience, not necessarily anything that shows up in a book.

It's seems to me that the biggest issue is a toss up between a totally out of range first tread height, or a variance larger than 1/2" or so in the middle of the run. I never gave much concern to variations when descending a run, since you are basically just controlling gravity as you drop your leading foot on each tread, and a 1/4 to 1/2" variation when heading down doesn't seem to feel like a big issue.  Ascending is when folks have issues, since your brain is quickly doing the math on when your foot needs to be based on the last tread climbed. That's why an odd first step height tends to really cause issues, since it starts the whole process with bad information.
 When building stairs there is a step called "dropping the stringers" when you do your layout with a square, then cut the thickness of the tread stock off the bottom of the stringer.  Otherwise the first tread will be higher than the others by the thickness of the tread material. I have seen many occasions, particularly on outside deck stairs, when this wasn't done, and falling face first onto the stairs while heading up, is a regular event. Another guaranteed tripper is having a few nice even risers, then one that's at least 1/2" higher. The brain gets you nicely set up to climb, things are going well, then the toes fail to clear the lone high rise, and it's a face plant.
In the picture shown I wouldn't bother changing a thing. The slight decrease in riser height as you ascend the run is of no real consequence, and it will be just fine if left undisturbed.

[Spork]

Many moons ago I did field measuring and design for a custom stair building company. All of the following is based on the tricks I picked up from fellow stairbuilders I worked with, and my past experience, not necessarily anything that shows up in a book.

It's seems to me that the biggest issue is a toss up between a totally out of range first tread height, or a variance larger than 1/2" or so in the middle of the run. I never gave much concern to variations when descending a run, since you are basically just controlling gravity as you drop your leading foot on each tread, and a 1/4 to 1/2" variation when heading down doesn't seem to feel like a big issue.  Ascending is when folks have issues, since your brain is quickly doing the math on when your foot needs to be based on the last tread climbed. That's why an odd first step height tends to really cause issues, since it starts the whole process with bad information.
 When building stairs there is a step called "dropping the stringers" when you do your layout with a square, then cut the thickness of the tread stock off the bottom of the stringer.  Otherwise the first tread will be higher than the others by the thickness of the tread material. I have seen many occasions, particularly on outside deck stairs, when this wasn't done, and falling face first onto the stairs while heading up, is a regular event. Another guaranteed tripper is having a few nice even risers, then one that's at least 1/2" higher. The brain gets you nicely set up to climb, things are going well, then the toes fail to clear the lone high rise, and it's a face plant.
In the picture shown I wouldn't bother changing a thing. The slight decrease in riser height as you ascend the run is of no real consequence, and it will be just fine if left undisturbed.

The problem was that in adding another 3/4 ... that first step was going to be a doozy.

I've pulled off the 2x 's now and replaced them with 3/4 ply... and dry fit the finished treads for the first 4 steps.  I'm waiting on some ordered trim or I'd go ahead and affix them permanently... but I can't until it comes in.  (I should have just made the cased opening, but ... ordered it when I ordered my upstairs doors.  So now I wait for it.)  So essentially I have the same rises as the original pic (after treads are on there) with an additional 3/4 rise on #5 right before the turn.  That brings it up to 7 3/4, which is in line (more or less) with the others.

[paddedhat]

Very nice job!