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I am extending the width of my stairs, and need to remove the existing sub treads and risers. They appear to be glued (construction adhesive I'm guessing because it is brown) and nailed. Is this going to destroy the stair stringer when I remove them?

In case it is helpful, the reason why I am removing them is that I want to install new, wider subtreads and risers so that the wood flooring that is attached to them has a continuous surface. The new wider subtreads and risers would be attached to two new trus joist stringers that will be installed where the previous pony/cheek wall was (where you see the exposed 2x4s in the images below).

An alternative would be to just add new subtreads/risers for the additional width of the stairs, and make sure that they are level. But I think that is risky because there would be effectively 2 separate surfaces/platforms that the finished treads and risers would be attached to, which could lead to problems in terms of wood movement, etc. I'm trying to decide which is the less risky path.

Images

Picture of Stairs Existing condition Sketchup drawing showing existing and new Detail showing subtreads and risers attached to stringer

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  • Here is what I ended up building: !stairdetail1 and ![stairdetail2] (i.imgur.com/FnBf2IW.jpg) and !stairdetail3 and !stairdetail4
    – Oren B
    Dec 7, 2014 at 6:50
  • I installed two TrusJoist Stringers for each section of the stairs, joined to the existing stair stringer and upper and lower ledgers (all connections used structural screws). It might be overbuilt (I needed to err on that side of things since I rent this property) but I think this is especially important because I will be mounting a metal railing system to this section of the stair when done. The good thing about using 2 stringers (3.5" of total material width) is that the lag screws for the railing posts will have something very solid to 'bite' into.
    – Oren B
    Dec 7, 2014 at 6:56
  • If I had to do it all over again, I would seriously consider just rebuilding the whole stairs, because the tread/riser dimensions were different and at irregular angles on every stair. Trying to match the new stringers to the old ones took lots of adjustments. If anyone sees anything "off" about what I ended up building, please let me know. I will be adding 2x4 studs below the new stringer, but those are pretty much just for attaching drywall. I'll keep adding pictures as I complete the project.
    – Oren B
    Dec 7, 2014 at 6:59

2 Answers 2

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I think the least invasive way to handle this is to add two more stingers, one right against the existing stairs(essentially just a nailer) and one out at the ultimate width of the new treads. This way you don't have to remove the old sub-treads/risers or change the height of your treads, which would cause you grief when you get to the top of your staircase. Once you've got your new stringers in just apply sub-treads and riser to match the existing construction and you're good to go. The bigger problem is that no matter how you construct it, the landing or the the lower staircase will have to be modified to make the intersection work properly. enter image description here This illustration shows how the problem could be fixed by lengthening the landing and pushing the lower stairs out (assuming you can do this). You could accomplish the same effect by pushing the landing to the right but it looks like your landing is captured on that side in the pictures. Although this fixes the stairs the railing system will still have an unusual transition but it's not too bad depending on how far you need to extend your treads.

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  • Thanks a lot for the feedback/ideas! To confirm that I'm understanding this: you think it would be ok to install subtreads and subrisers only over the new section of the stair? By new section of the stair, I mean the parts of the stair created by the addition of the 2 new stringers. This was the part I had concerns about, whether it was a bad idea to have 2 separate pieces of plywood per stair tread/riser. I'm working on drawing up the answer to the other problem you pointed out (you can kind of see it in the new drawing where we extended the landing just a bit for the new stringer).
    – Oren B
    Nov 12, 2014 at 5:53
  • Yes, it should be fine to scab on sub-treads/risers as long as they're supported well. Just belt sand off any disparities before applying your finished treads/risers. I would argue that floating your treads as Mazura suggests (although doable) has the downside of not providing enough substructure to attach your railing/mid newel in certain circumstances, and given the unusual nature of your project you're going to want to have every option available to you. Just my two cents, but I do tend to err on the side of over-building;)
    – user23534
    Nov 13, 2014 at 2:54
  • Here's what I actually ended up building: !stairdetail1 and ![stairdetail2] (i.imgur.com/FnBf2IW.jpg) and !stairdetail3 and !stairdetail4
    – Oren B
    Dec 7, 2014 at 6:45
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If you used 1" solid oak stair treads they could float that distance; you're going to use hardwood flooring? stair-treads.com enter image description here

Stair treads could be directly applied to the existing sub, so long as it will still be an acceptable rise. Continue with hardwood on the second floor to meet the new landing height, transitioning back down further into the hallway if necessary.

To answer your question; it's entirely possible and I'd expect at least a few of the stringers' beds to split-off unevenly. Prepare for having to make new stringers or at least repairing them; otherwise leave it alone.

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  • Thanks for the feedback. We are using 1" solid reclaimed oak stair treads, fabricated by a high-quality supplier. When you say 'float the distance, you mean that the 1" tread would be able to span the distance of the old pony wall (~4.5") without support underneath?
    – Oren B
    Nov 12, 2014 at 5:58
  • @OrenB I'm not a structural engineer, but I don't see why not; the railing is going to take up... +3"? I don't envision them ever being exposed to enough weight to lever them. The risers will help hold them down. -The stair treads can float but don't support the ends of the top-rail from them if you can avoid it. It should attach to the wall at the top and have its own post to the floor at the bottom (and probably one where it kinks). Take a look here to see why I'm not so concerned; you can't step there.
    – Mazura
    Nov 12, 2014 at 6:23

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