Curved Stairs

SAcarpenter

Can anyone tell me the method for framing a curved saircase and the rake wall that supports the rail and ballusters. Or at least the math required, or even an article on it. I've framed alot of stairs but never a curved set. I just cant seem to grasp it. Am I just an idiot or is this as hard as I think it is?

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Warren

SA, It depends on the situation. I had never done one for 20 years and then I finally did a couple. Sam another carpenter doing a set once and got some pointers from him. If you have the radius wall to go against it makes it much easier. Not much to say about the math since each tread will be the same, just a series of wedges. Do a search here and see if you find any info. I know there are pics as I have posted some myself.

strathd

I scanned an article out of a book I have that explains how to build and layout curved stairs. If someone can tell me how to get them from my scans to my pics I will be able to upload them. Been trying to do this for a half hour.

If not I will take pics of them and post them in a while.

strathd

Have'nt had the opportunity to build one yet. Does'nt look to tough though. It's all about establishing the radius and the layout on the floor.

SAcarpenter

How would you make the inside stringer if it was to be self supporting

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strathd

The third pic gives a generalization. Maybe you ought to read it again ?

ClemS

there are several factors to consider building these sets. I never framed one out because all our stairs are shop-built, but I've laid them out many times.

Usually you're somewhere between a 7' and an 8' radius. Could be a much greater radius, but usually not shallower because of the tread requirements and aesthetics. On a tight radius, keeping the inside tread at a minimum of 6", your outside tread will become very deep and unsightly.

So. See what radius works best for the number of treads and the room that you have. Pin your point and scribe the outside and inside stringers. Take the circumference of either one and split that up into the number of treads you have. Snap all your tread lines back to your pin point. Then it's just a matter of cutting pieces.

As far as structural stringers go, it's a laminating process. You have to rig a temp wall, set your tread points on it and then laminate the stringer wild and cut plumb and level once it sets. Pain in the neck to do in the field, but if I ever get enough $ for one I'd love to give it a shot. You can build up girth with 1/4" ply to whatever you feel comfortable with given the number of treads. Shops usually give us a 2"x12" lam stringer for a 10' tall stair.

It's as time consuming affair as anything you don't do every day, that's why it pays to farm this type of stuff out to stair shops. They're geared up with all the widgets and movable walls and CAD sheets.

trimmerdennis

I built a curved stair a few years ago. As far as I can remember the outside radius was about 10', with the inside radius, a wall built by the framing crew. I established the outside radius on the floor, about 4' from the inside. Built a temporary wall at that line, with every other stud at the face of the riser. Useing a story pole, I then established each tread on those studs. then laminated 1/2" plywood, screwing the first layer to the studs on that line, then 3 more layers glued and screwed to that one. After all layers were glued up inside and out, I layed out the treads and risers. then before cutting it all out I installed my rough risers in between the two stringers, glueing and screwing it all together. At this point the false wall can be removed, and everything cut out. I then added 2 by material as rough treads between the stingers to strengthen it more. The finished product was very strong and graceful.

woodworkbykirk

the closest i did in regards to this was work on the floor openings and curved walls for curved stairs. it was while i was a registered apprentice and working on a framing crew. our crew consisted mostly of apprentices so the boss hired a friend of his on part time who had retired from carpentry but is a master stair builder. learned quite a bit from him. if memory serves correct the curve wall has to have studs on the flat 12" o.c and the inside radius can be no less than 98" roughly.

also in my apprenticeship courses we were given modules which covered circular stairs, im pretty sure i know where it is. if i can get to it ill scan it and email it to you. cant guarentee anything right now as im pretty busy but ill try

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Cache

If you want it to have an open handrail, the easiest is to do it with steel.

Girlscanbld2

Check out the pic's on the "Random framing pic's" thread...Timuhler posted photos of a staircase that may help you.

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trimmerdennis

Building up a curved stringer out of 3/8 or 1/2 " ply, makes for a very strong stringer. Essencially you are building a curved glulam beam. I build them out of 1/2" ply 16" wide 6 or 8 layers if it was to be self supporting, maybe more. Once its glued up and braceing between stringers, very very strong.

RobQuillin

I always lay the tread layout on the floor to get the layout how I wanted it. Then I built a temporary wall and laminated 3/8 plywood to the wall at the angle I needed the stringer. Once I did that I was able to transfer my tread layout to the stringer by leveling up from my layout on the floor. ONce I did that I just boxed in my treads and risers and finally removed my temporary wall.Just remember that the inside tread can't be any narrower that 6 inches and you typical tread width needs to be 18 inches ron the inside handrail. If you keep this in mind than even if the steps have a double curve to it they will be a comfortable staircase to use.
I also did a custom handrail for the staircase. To do this I ripped wood down to 1/8 inch strips to laminate togeather for the handrail. Once I did this I installed L blocks to the treads directly below where the handrail will go. Once this was done I placed waxed paper over the steps and glued and clamped the wood togeather clamping it to the L blocks. This will create the proper bend and twist to the wood that the handrail needs. Once the glue is dry then you just sand and shape the wood to the profile you want.

Timuhler

I've got some pictures here http://picasaweb.google.com/TimothyUhler/Hawkstone# of how we did it. John Kirkpatrick walked me through it over email. He has done this fairly often I think.

We laminated enough layers to make a 3 1/2" stringer, so that is 14 layers of 1/4" ply. That was time consuming, but it had very little bounce in the outside stringer.

There is some math on Joe Bartok's site for the "plate" on top of the rakewall. I'll try and find it when I get home tonight. As far as the stairs go, it was less than 8 hours for me to frame that stair. That was my first one. It really is not hard, its all components. So you can get a lot done fast. Cut all your risers and put them in a pile. Cut all the studs, 2 per riser height and then stack those against the wall. Same with treads, then its just putting it all together and keeping it plumb.

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Tim Garrison PE

I can address the math part of a curved stairs. I designed a curved stair for my home a few years back and was struck by the complexity of the math involved. So being a gearhead I wrote a spreadsheet to solve it. Also being in the software business I recognized that my neat little spreadsheet might be useful to others, so I spiffed it up and now sell the thing. If you're ever faced with designing a circular stairs, download the free demo, StairCalc Pro, and play around with it. You will learn quite a bit about how circular stairs work and their parts and pieces.