Adding a 3rd stringer to deck stairs

We had a PT deck, with steps leading from the lower level (basement/ground) to the upper deck (1st floor). The steps were 3' wide, and we had a series of 2, 2x6 on each riser, for a total of 11 risers. We had two stringers for the steps.
We had the PT flooring on our deck replaced with TimberTech. On our steps, we used 5/4" planks. The 5/4" planks have a 16" spam requirement, which means we now need to add a 3rd stringer in the center of our steps. Unfrotunately, the steps were put up before we realized the spam requirement.
Is it possible to add a 3rd stringer (down the middle) of 2x12 without taking off the steps?
If yes (or even if no), what is the easiest way to make another stringer to match the current two?
THANKS in Advance...
-- Jim
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Yes. If there is room to get in there. You need to consider how you support it at the bottom and how it attaches at the top. If you can figure that out then it should be no problem to fit a new one. If you "had it replaced" then it seems that the problem lies with the person who did the replacement. They should have noticed this at the time. Depending on the deal you had with them, I'd consider having them come out and pull the planks off and then add the stringer. They would have to be pretty clueless to put that stuff down with a 3 foot span. You would notice a problem after you installed the first board.

Get some cardboard. Fit a square into each angle formed by each step. Tack them on to the existing stringer. Tape them together. Cut along the bottom of the stringer. Untack. Place on new 2x12. Mark Cut.

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On Tue, 2 Sep 2003 13:54:42 -0700, someone wrote:

All that cardbpard and taping is more trouble than it will help, IMHO, and asking for error to creep in what with that taping together and then having to take the taped together mess to the new work piece. That much length of taped together cardboard will be quite flexible even across the flat way that you are depending upon being rigid.
Its "just" a matter of measuring and laying out. And yes, I used to be the layout man guiding a crew of union carpenters on complex framing jobs. BTW, don't be too obsessed with following every minor inaccuracy in the existing steps; layout the new stringer "right" based on the rise & run, and then fit it, there sounds like there is enough flex to take up the minor eighths that are probably floating around in the job.
Stairs are not rocket science, they are rise & run, I have detailed both wood and steel stairs for the shop to have the pieces pre-cut and then put together on site.
MHO, -v.
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[snip!]
What haven't you done? Did you used to shoot photos for Playboy, too?
Dimitri
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On Tue, 2 Sep 2003 23:40:04 +0000 (UTC), someone wrote:

I have a tendency to own businesses. What can I say. At one point I ended up starting a commercial framing company. I had done the drawings for a project, and then a major sub went belly up, and the GC was calling around looking for someone to do the job on short notice, and that's how I ended up framing for a while....

Welllll actually.... not in Playboy, but yeah I have done stuff like that, Nikon F & did my own color printing, how did you know....
;-)
-v.
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Had I felt he was comfortable with measuring, I'd told him the same thing, but since he was asking, I made another assumption. Absolutely it will be better to lay out the job, and any mismatch will be easily compensated with the flex in the comosite treads. The cardboard templates will be better if they are not cut out until stapled to the new board, even then, one good edge wll be enough to keep them lined up.
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wrote:

it
Unbelievable. You mean muddle is a word? I would have thought spell check would have got that.
I do proof read, but they still slip by once in a while. :-)
Try middle, instead of muddle!
-- Jim in NC
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"If yes (or even if no), what is the easiest way to make another stringer to match the current two?
=============Now, kids, he DID say EASIEST, not "Most Proper", right? OK then.
Easiest: trace a template from the edge of the existing stairs, being sure to include the edges of treads on the drawing. Cut it out like paper dollies and lay it on the new stringer stock. Now just gnaw it out, Bucky.
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