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Small Cabin Forum / Useful Links and Resources / Laying Out Stair Stringers
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rockies
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# Posted: 16 Nov 2018 20:20 - Edited by: rockies
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One of the topics I see on this site that a lot of people have trouble with is designing and fitting in a staircase in order to get up to their second floor or loft.

Many resulting stairs end up being too steep, with risers that are awkward to climb and treads that are too shallow to properly provide support for an adult foot. Many staircases are a disaster waiting to happen.

In designing a staircase every single step MUST be the same height. As soon as you step onto a staircase your brain sets the riser height in its memory and causes your body to "expect" that riser height all the way up or down the staircase. If one step is off by as little as 1/4" your body will "jolt" from the unexpected difference and you can experience a fall.

Since many people want to build their own staircases, here is a guide on how to lay out the stringers properly.

https://www.finehomebuilding.com/2014/11/05/laying-out-basic-stair-stringers

Remember, when you take the height from the surface of the main floor's finished flooring material to the top surface of the second floor's finished flooring material you divide it by the number of risers you want. Whatever the resulting measurement is must be the height of every single riser in the staircase.

rockies
Member
# Posted: 16 Nov 2018 20:38
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Another article with video on how to design the staircase.

https://www.wikihow.com/Build-Stairs

ICC
Member
# Posted: 16 Nov 2018 20:57
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Quoting: rockies
Whatever the resulting measurement is must be the height of every single riser in the staircase.


You are allowed a little leeway...... "The greatest riser height within any flight of stairs shall not exceed the
smallest by more than 3/8 inch (9.5 mm). "

rockies
Member
# Posted: 16 Nov 2018 21:55
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A little bit of "leeway" should not be allowed at all. If every step in a staircase is 7 1/2" and the last one is 7 7/8" it's a danger. It takes just one person to catch their toe on the edge and it's a fall (or a lawsuit).

Perhaps that "leeway" is to accommodate sloppy workmanship?

darz5150
Member
# Posted: 16 Nov 2018 22:22
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Geez rockies. Reread your posts from earlier in the week when you said mwarren should flip his stairs. And it would be OK. Now, days later, you are a stair building master?
Sorry. You were wrong then. And you are wrong now. Just because you have a computer, doesn't make you a master carpenter.
Post pictures when you build something. Not just computer drawings.

darz5150
Member
# Posted: 16 Nov 2018 22:38 - Edited by: darz5150
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Rockies says: about mwarrens stairs.
It's just flipping it around so that the bottom become the top. It's still the same length and height in the same space, it's just that the risers become the treads.
There comes a point, however, where the differences between riser heights and tread depths start to even out.
It's still the same length and height in the same space, it's just that the risers become the treads.
Today:
Perhaps that "leeway" is to accommodate sloppy workmanship
Nothing personal bud. But try not to be the guy that knows everything because you can google it and become a "Jeenyus"
Instantly.

Atlincabin
Member
# Posted: 16 Nov 2018 22:58
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I gotta agree with rockies here to some degree. The less variation in step height, the less chance of a misstep. I'm willing to accept up to about 1/8" variation to account for cupping of boards and such, but no more than that.

If you must adjust a step (like change the rise to accommodate a change in flooring), best to do either the bottom one or the top one, certainly nothing in the middle of the run.

My two cents.

rockies
Member
# Posted: 16 Nov 2018 23:38
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Darz5150: You are correct. I did make a mistake in suggesting that the stairs in that case be flipped around so that the risers become the treads.

However, I did take the suggestion in that thread to use a computer design program and see what could be done, and as it turns out you can build a much safer and easier to use staircase in approximately the same space by adjusting the riser heights and tread depths.

I will add, however, that the focus of my posts are not to make myself look like a "jeenyus" but instead to point out safety issues and possible solutions.

While mwarren's cabin is certainly beautiful and probably well built doesn't mean that all I'm going to do is reply with "Hey! nice cabin! Post more pictures!"

If I see a safety issue I'm going to talk about it. I may make a mistake but my concern is genuine.

darz5150
Member
# Posted: 17 Nov 2018 00:00
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@ rockies. Understood. You had concerns and were trying to be helpfull. That's a good thing. Let's blow this episode off.


snobdds
Member
# Posted: 17 Nov 2018 02:24
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I love building staircases. I put this one in the cabin this last summer. It's six feet up to the 90 degree turn, then 3 feet up to the loft. It follows the roof line to not feel cramped. It's out of the way and is ergonomic. For some reason I can only find one picture of it.
20180901_085541.jpg
20180901_085541.jpg


neckless
Member
# Posted: 17 Nov 2018 05:01
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i have built a lot of stairs out of steel for commercial buildings....when u do the math and it 7 1/2 " riser they have to be that .... if u lay out 12 risers on a stinger and out a 1/8 here and there your last one will be short and some where there is a long one..... even a wide pencil mark can make your stair just not work out.... the brass dodads that clip to your square can make things alot easier the stairs in pic are nice but u need a 1" noseing on all stairs

ICC
Member
# Posted: 17 Nov 2018 09:34
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rockies, The permitted by code 3/8" variation between maximum height and minimum height is not there to allow for a sloppy worker but to allow for small miscalculations or a tolerance at the bottom or the upper floor levels. That also can help compensate for on the fly design changes such as not installing carpet and pad but installing hardwood or ceramic tile, etc. I cannot begin to count the number of times I've had to work around that. When the variation is at either end of the run it is seldom if ever noticed. And yes rockies, you should get your hands dirty and build something someday.

creeky
Member
# Posted: 17 Nov 2018 10:39
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My gf lives in a house built at the turn of the last century. The heights are out 1/8" or more on a number of the risers.

Interestingly, she tripped and fell on them when first looking at the house. Meh. She still bought it.

But it does show, get it right the first time. Folks will be living with those stairs for decades. For my money if I had a variance I would put it on the last/lowest step. And maybe make that step a bit larger to act as a visual indicator.

Building is the most fun. And nothing like some hands on to clarify the learnin'.

Borrego
Member
# Posted: 17 Nov 2018 12:16
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Quoting: ICC
The permitted by code 3/8" variation between maximum height and minimum height is not there to allow for a sloppy worker but to allow for small miscalculations or a tolerance at the bottom or the upper floor levels.


I've built a few stairs and the 3/8" is usually needed. When I inspected homes, it was common to find this discrepancy with almost all staircases. as a matter of fact, I don't know if I've ever seen a 'perfect' staircase.....
For those who have built them, you'll know that even the difference between 'taking' the line or not can mess up the stairs layout.....
Maybe I'm just no good though.....? But here's a pic of one of the last ones I did...
These are 'L' shaped like the ones Snobdds did...the math on those can make your brain smoke. The specs the architect called out on the plans did not work of course, I don't know why they bother...
IMG_20160313_1457422.jpg
IMG_20160313_1457422.jpg
IMG_20160906_1435026.jpg
IMG_20160906_1435026.jpg


Atlincabin
Member
# Posted: 17 Nov 2018 14:50
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Seems to me that the math isn't that bad. Just take the difference between levels and divide by the number of steps you want. A good place to start is with about 7 1/2 inches of rise per step, then adjust up or down to fit overall. There are some "ideal" numbers for the rise/run (typically the rise should be around 75% of the run), so once you figure out the rise, it is easy to figure the run as well. Of course, every situation is slightly different and may require some adjustments but those general rules work pretty well. Must be some youtoob tutorials out there too.

Greenland South
Member
# Posted: 17 Nov 2018 15:40
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Here is a website I find useful from time to time. https://www.blocklayer.com/

ICC
Member
# Posted: 17 Nov 2018 16:10
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Borrego, right, perfect stairs are seldom seen except as drawn on plans and sometimes those are drawn wrong. As you alluded to cutting on the line, to one side or the other can introduce differences. Then there can also be a variance in milled thickness on occasion plus a warp this way and another the other way.

I do have a staircase in the shop that is near perfect. Welded steel and accurately marked. But a change in flooring after all was started throws off the last riser height at the top.

IMO stairs are probably one of the harder parts of building. And dormers and hip roofs can be a problem for some diy.

toyota_mdt_tech
Member
# Posted: 17 Nov 2018 16:59
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Quoting: rockies
A little bit of "leeway" should not be allowed at all.


I think he meant the code min max, but once a step rise is set, they all should be identical.

Borrego
Member
# Posted: 17 Nov 2018 17:50
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Quoting: Atlincabin
Seems to me that the math isn't that bad. Just take the difference between levels and divide by the number of steps you want.


I didn't mean the math is difficult that way, that's easy.... I meant having the number you arrive at on paper come out right when you cut....you must be good to keep it within 1/8"....

Just
Member
# Posted: 17 Nov 2018 19:19
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I never professed to being good so i buy them precut .some one eles and rocky can work on being perfect .

rockies
Member
# Posted: 17 Nov 2018 19:58 - Edited by: rockies
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One thing that seems to result in a lot of awkward, overly steep staircases is the need (desire?) to have all the steps in one section. Mwarren did that with his staircase and the reason he did so was probably because building one length of stairs is easier than building an "L" shaped staircase with a landing.

An easy method I saw on an episode of "This Old House" involved a staircase that had a couple of steps up to a landing and then the rest of the stair heading off the landing to the left. The crew calculated the riser height as being 7 1/2" so they built a box out of 2x material for the first step and attached the tread to the top to get the finished riser height.

Then they built another box for the 2nd step (at 15" with the tread attached) and then a third box for the landing (at 22" with the tread attached). Then they built the rest of the stair like a regular staircase with stringers, 7 1/2" risers and treads.

Mwarren could do that quite easily for his staircase since the stairwell overhead seems to be completely open (there wouldn't be any issues with headroom clearances for the first step or the landing). Once he figured out the correct riser height he needed he would have a much safer staircase that would be pretty close to perfect

darz5150
Member
# Posted: 17 Nov 2018 20:49
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Quoting: rockies
he would have a much safer staircase that would be pretty close to perfect

Glad to see you still have a sense of humor.😀
Mwarrens stairs..............
Since you are good with computer designs. Maybe you could do a quick stair layout, with a landing. And since stairs waste a lot of space. Design him a storage area under the stairs with boxes and compartments to store his winter gear. Low boxes for boots. A longer rectangle for skis and snow boards. And Other spaces for his deflated ski tubes. He might like your design, and re do the stairs for safety sake and also for the storage area. 🙌🏂🎿

toyota_mdt_tech
Member
# Posted: 18 Nov 2018 10:34
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Quoting: Just
I never professed to being good so i buy them precut .some one eles and rocky can work on being perfect .


Thats the way I roll. I suppose if I had to, I could get it done and do it right, probably lots of scrap wood in the beginning.

When the inspector came to sign off on my cabin, the first thing he headed for was the stair treads, tape measure in hand. He was measuring the rise and run. I said ti him :I have to be honest with you, I cheated and bought the pre cut risers from home depot.

I had no railing either and my distance to earth required it. I told him the area he was measuring from I was actively back filling by hand when he drove up and finish grade was going to put me under the rail requirement. I have a rail on the porch, but not the stairs.
All my more elderly visitors complain no rail, I am entertaining the idea of installing one.

Borrego
Member
# Posted: 18 Nov 2018 12:08
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Quoting: toyota_mdt_tech
probably lots of scrap wood in the beginning.


Sometimes it's a good idea to get a sheet of 3/8" plywood, cut it into 11-1/2" or 13 - 1/2" (if you're using 2x14's for stringers) widths and do a test run cutting. Especially useful if you're using more costly 2x14's for stringers......
Make your mistakes on the plywood....

toyota_mdt_tech
Member
# Posted: 18 Nov 2018 20:19
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Quoting: Borrego
Make your mistakes on the plywood....


Excellent idea and if its up to snuff, use the plywood as a template and cut out the 2X14. :D

Malamute
Member
# Posted: 18 Nov 2018 20:57
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One thing Ive forgotten once was doing the rise and run math, laying it out, then.....forgetting the tread thickness in the rise calculation for the first and last treads. Height up from lowest point on the cut isnt the total rise, its the total rise minus the tread thickness.

snobdds
Member
# Posted: 19 Nov 2018 16:30
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Quoting: neckless
the stairs in pic are nice but u need a 1" noseing on all stairs


The noseing will be added when I put down the final hardwood flooring...

ICC
Member
# Posted: 19 Nov 2018 18:31 - Edited by: ICC
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Quoting: snobdds
Quoting: neckless
the stairs in pic are nice but u need a 1" noseing on all stairs


The noseing will be added when I put down the final hardwood flooring...



Not completely true when the IRC is the rule book.
And the IRC rule is more flexible than that statement. When the riser is solid (not open)the nosing can be from a minimum of 3/4 inch to a maximum of 1-1/4 inch. When the riser is open there are other rules to be followed and it is possible to not have a nosing at all if the tread is wide enough(11 inches or more). There is also a variance of 3/8"permitted between the tread with most projection and the tread with the least projection.

https://timnath.org/wp-content/uploads/2014/03/2012-RESIDENTIAL-STAIR-GUIDE.pdf

https://www.yakimawa.gov/services/codes/files/2015-IRC-Residential-Stair-Code-Require ments.pdf

The Stairbuilders and Manufacturers Association has a very good illustrated guide available. $5 and it is what the first link above is taken from. Illustrated guides are much easier to follow than reading the IRC text, IMO. https://www.stairways.org/SMA-Books Virtually all stair codes in the US are based on the IRC.

rockies
Member
# Posted: 19 Nov 2018 19:14
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Another thing to remember is the handrail design. The balusters can not be farther apart than 4" and the rail height should be between 34-38" above the nosing of treads and landings.

One safety thing I saw was to install two handrails on the wall side of the staircase, one at the code required height and another one lower down for children.

Borrego
Member
# Posted: 19 Nov 2018 19:44
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Quoting: rockies
Another thing to remember is the handrail design. The balusters can not be farther apart than 4"


If you're using balusters....I doubt many cabin builders bother with this....
You are also not supposed to build 'climbable' railings, but they sure can be cool....
Of course if it's to be an inspected project, then ya gotta do what ya gotta do....

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