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Dear PoPville – Thinking about Converting a Spiral Staircase

by Prince Of Petworth February 26, 2013 at 2:30 pm 15 Comments

Dear PoPville,

I am thinking about possibly converting an existing spiral stair case to regular type staircase. Before I start calling companies I wanted to here from architect readers if it is possible to begin with.

The spiral stair case is in the middle of an open-floor first floor and it goes two levels. The floor to ceiling height between first and second floor is 103″. First floor ceiling to second-floor floor is 14″ thick. Second-floor level isn’t open floor plan so it has three walls surrounding the staircase. Second-floor floor to second-floor ceiling is 104″. Second-floor ceiling to third floor floor is 14″ thick.

The spiral staircase opening is 75″ by 75″ square for each floor level.

Is it possible to build a staircase that turns twice or three times on each floor?

  • dat

    I am not an architect, but I’ve done a fair amount of home renovation. Here’s my 2 cents. First, you’ll only be able to have 1 turn in a traditional staircase (wood stringers) since you’ll need to maintain adequate headroom. To go from your first to second story, you need to ascend 103″+14″=117″. The maximum riser height allowed by code is about 7″. 117/7 = 16.7. That means you will need 17 risers. 17 risers will require 16 treads. The minimum tread depth is something like 9″. That means your staircase will need to be 144″ long. Divide that in half and you get two sections of 72″. Although this fits in your space, this does not account for the landing you’ll need at the point where the stairs turn. Minimum landing size, I believe, is 36″x36″

    This is going to be right — really really tight — but you might be able to make it work with some creative planning.

    • ah

      I think the added problem here is that in order for the stairs to end up where they are on the second floor, the landing will be about 48″ under the ceiling, which is not so convenient. (two 72″ runs plus a landing of 36″ means you’d need 108″ horizontal inches of space).

      Even if you make the two stair runs unequal lengths (say the lower one is 108″ and the top is 36″, then the longer run of stairs will require ducking for the last few.

      In other words, can you open up the opening for the stairs?

  • Is it “possible”? Sure, but it isn’t anything that anyone would want to, or be comfortable doing.

    The min width by code you can get away with on an internal stair is ~28″, and thats with handrails on both sides, something more akin to a metal fire escape you see in the backs of houses/apt buildings. You want to just go wall to wall then you have to kick the width up to ~36″

    While you do seem to have enough space for a three turn , you have to make up 9′ of vertical climb. The only way to do that is to make each riser a solid foot, to 14 inches. Just for comparison sake, the typical stair riser is 8 inches.

    So yes, you “can” do it but you end up with a super narrow and ungodly steep staircase that is virtually impossible to haul anything up, or rwalk up and down for most people.

    There is a reason a spiral staircase was put in originally. It was the least “objectionable” solution.

  • TG
  • “Is it possible to build a staircase that turns twice or three times on each floor?”

    Yes – it’s called a spiral staircase.

    • anon


      • Anonymous
  • When we were having work done on our 1909 Petworth home, we asked about making some changes to the basement stairs, which are straight, not spiral. We decided against it after finding out that the old stairs don’t meet current code and any changes to them would mean we would need to completely alter both the basement and first floor layouts of our home! If it ain’t broke…..

  • Anonymous

    But if the train is going 45 mph, then I think yes, the front of the train will get through the tunnel before the back of the train.
    I win!

    • Anonymous

      Assuming that the train is going forward of course. If it’s going backward, then the back of the train will make it through the tunnel first, unless there’s a headwind.

  • That’s a quick way to clutter up your spacious living room.

  • poo poo

    just move it so that it’s adjacent to the wall. problem solved.

    • ah

      1) Landing above is on wall side, so stairs seem to need to run towards where the picture is being taken from.

      2) Opening is 75″x75″. A straight run of stairs will be only ~5′ below the ceiling (or less) at the edge of the opening.

  • OP

    Thank you all for your comments and I certainly appreciate all your insights.
    The spiral staircase is actually wide and it doesn’t feel cramped at all. There is a skylight on top of it so it is bright in the entire box. The treads are 17” deep and are 30” wide from the post. The house has open-able floor cutouts on both levels so big items can easily be moved upstairs through those, so the stair doesn’t have to accommodate for that.
    If there is a way to do it, it needs to continue to be open feel just like the spiral. Also, I don’t think it is possible to widen the opening so 75” by 75” is what we have to work with. The landing on the second floor is exactly opposite from the star of the stair on the first floor which faces the front door. Second floor landing area is big rectangular area with 4 doors to four rooms plus the start of the stairs going to the third floor.
    Weather or not I am able to change this, I do need to make the steps safe for walking with socks on. Anyone installed rubber treads or any other product on top of the metal/wood staircase? If so please share info.

  • architect here.

    would need better existing dimensions. but… perhaps winders are the solution. the current building code req’s 7″ riser and 10″ (variable depending on jurisdiction) however, with winders you can reduce the tread to 6″ (again variable) at the narrow end with some restrictions.

    Depending whether you are getting proper permits for this construction, you might “pinch” those dimensions reasonably. I think you might be surprised how much stair you might fit.

    As a resale issue a regular stair even with winders is much more desirable over a spiral stair. Builders don’t like to do them as they’re labor intensive. But if you could find a good affordable carpenter, it should be an option.




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