Advice needed on finishing basement stairs

Old 01-05-14, 07:37 PM
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Advice needed on finishing basement stairs

On of the first things I'd like to tackle on finishing the basement in my house is making the stairs safe and more than just functional looking.

Ideally, I'd like to finish them such that the side closest to the camera in the picture below is open underneath (where I currently have a dog kenel built) with a small wall going up from the stairs that has balusters and a railing. The staircase being open underneath (on the near side) is somewhat critical to the initial draft of a floor plan to keep the basement from feeling to closed in and cramped when you first come down the stairs as well as providing a decent entryway into a planned kitchen area to the left of the picture

The red lines outline roughly where I'd like the mini-wall holding the ballusters to be. The yellow outlines and vertical lines are roughly where I'd like the ballusters and railing to be.

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I plan to carpet the stairs and am hoping to use the existing stringers, risers, and treads.

I've tried finding information on how to go about building such a mini-wall for an open-underneath staircase like this on the web, but I haven't been very successful (although I've seen a few pictures of such a thing). I must not be using the right search terms or there just isn't a lot of info out there about this. "Knee wall" and "open staircase" generally result in things not too terribly useful.

There are two main things (and lots of other things) that I don't really know a lot about. The first is structural support for stairs. It seems like I could move the 2x4s that run along the bottom of the stringers on the outside to the inside of the stringers. I'm guessing it'd be a bad idea to just remove the 2x4s I've marked with green lines in the above picture - they were there before I built the kennel. Would it be possible to get rid of them if I added a third stringer in the middle of the existing two?

Below is a picture of the underside of the staircase.
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The other main thing is how I would go about building the mini-wall on the near side of the staircase while leaving it open underneath. I'm planning to build a floor-to-ceiling wall on the far side of the staircase.

Below is closer picture of the treads/risers on the near side of the first picture.
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Should the treads/risers be cut back to flush with the stringer and the 2x studs for this mini-wall (that the balusters would attach on top of) be attached to the stringer? Would that be too much torque on the stringer? Could that be avoided by 2x lumber between the stringer and the other one (or perhaps a third one as mentioned above)?

Another thing is how to deal with the pole that holds up the I-beam that holds up the house? It's spaced just far enough from the stairs to be a problem for a wall that is 3.5" + .75" (2x4 + drywall). It is 3" from the stringer, 2" from the tread. I'd rather not have the pole move because of the cost of doing that.

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Here are a couple examples a mini-wall on a staircase I found on the web.

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Thanks in advance for any helpful ideas, insight, or advice.
Old 01-07-14, 11:02 AM
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Your inspector is not going to like the dog kennel under the stairs.
Old 01-07-14, 03:09 PM
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Yeah, I forgot to mention that the kennel is going away when I finish the stairs.
Old 01-08-14, 01:21 AM
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I suspect the vertical 2 x 4s were installed by someone to stiffen up the stairs, to minimize the wobble effect when used. Typically, 3 stair stringers are normally used, but many installations having just 2 stringers are working adequately. Stringer lumber species and dimensions are usually the determining factors as to how stable they perform in service. Adding a middle stringer might just make things work well for your plan.

As an alternative, an option I'd consider would be to remove the 2 x 4s, and replace them with longitudinal 2 x 4s glued and screwed to the bottoms of the 2 existing stringers, oriented in the "flat" direction. The inverted "L" feature will stiffen the stairway considerably, as it creates bottom flanges similar to those on bridge girders (making the section modulus much larger), which increases the resistance of the stringers deflecting under load. The resulting arrangement could easily be framed in and hidden, is relatively cheap and simple to install, and would be a lot less work than (accurately) cutting and installing an additional middle stringer.

Regarding that pesky column, you could possibly conceal it by incorporating it into a floor-to-ceiling baluster for the stairway's railing. Properly trimmed out, few people would realize there's a column hiding inside.

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