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mntnvew 04-13-2009 09:58 PM

Stair Stringers
 
Hi All,

Please forgive me in advance for asking this as I am sure it has been brought up a million times before...

I am planning a deck that will have a finished height of 147" off the ground. I am getting ready to plan the stairs and well, I wanted to know everyone's thoughts on stairs/stringers for a deck of this height/stair run. The lumber guy said I should be able to get the required run of stairs with three stringers from 20 foot 2x12 stock. Is this accurate? I calculated 7.75" for each stair and that equates to 19 stairs, can I get that out of a 20 foot board? Are three stringers enough to support, I do have 2 6x6 posts in the ground at 7' from the deck edge and then 2 more 6x6 posts at the end of the run? Should I dbl up the stringers or the three single stingers enough? Is this going to be steep run? I want it mild not too steep so I can carry 4x8 sheet material up without hassle.

Any other thoughts are appreciated on stair building and my situation before proceeding.

Lastly thanks in advance to all!!! :thumbup:

Wildie 04-13-2009 10:12 PM

Would it be possible to have a landing half way down?
Then you could have two runs of stairs!
The stringers would be much shorter and the stairs would be safer in case of an accident!

mntnvew 04-13-2009 10:21 PM

Quote:

Originally Posted by Wildie (Post 259550)
Would it be possible to have a landing half way down?
Then you could have two runs of stairs!
The stringers would be much shorter and the stairs would be safer in case of an accident!

Thanks!

I guess it is a possibility, I didnt account for it in the lumber delivered the other day, nor the holes with the excavator (in MT and it is really ROCKY!), but I could fix those but the landing wouldnt be but 2-3 foot, would that be acceptable/is it worth it??

Other thoughts anyone?

Scuba_Dave 04-13-2009 10:23 PM

You are just over 12' rise
I used a 20' 2x12 to rise less then 10'

Quote:

A flight of stairs shall not have a vertical rise
greater than 12 feet (3658 mm) between floor levels
or landings.

A landing has to be 3'

mntnvew 04-13-2009 11:03 PM

Quote:

Originally Posted by Scuba_Dave (Post 259557)
You are just over 12' rise
I used a 20' 2x12 to rise less then 10'



A landing has to be 3'

Well, I do have to fill in the area beneath the stairs, the pole barn was build end of last year just before winter, before I could get the ground leveled out, so there is 8 inches that will need to be filled so that the ground is up to the bottom of the barn tin/trim. That would reduce me to just under 12' so I could do it w/o a landing and still be OK with code. I think.

Ron6519 04-14-2009 06:02 AM

" That would reduce me to just under 12' so I could do it w/o a landing and still be OK with code. I think."
I think a perfectionist would do it differently. "Thinking", it will be to code would be a waste of time and money if it wasn't.
A single flight of stairs from that height make no sense.
Ron

RegeSullivan 04-14-2009 06:45 AM

If your rise is about 7.75" your tread should be about 11" for a comfortable outdoor step. Many fire codes will not allow 12 feet of total rise w/o a landing. If you need to have this inspected or plan on selling the house in the future you may have problems with a building inspector at some point with a total rise that high with out a landing.

From personal experience I can tell you the wider you can make them the better. For me 42" would be minimum, 48" would be good 60" would be great but often that is not practical. 12" OC is the most I would go on stairs so the number of stringers depend on how wide you make them. Three stringers would only give you about 24" depending on the overhang. It is unlikely you will get an entire stringer from one board so be sure your splices are supported by a post. You might want to keep the overhang to a minimum so attaching the railing is easier.

Rege

Willie T 04-14-2009 09:45 AM

Just to give you some numbers to think about.....

11" treads... 19 of them
7.75" riser height
Total rise 12' 3"
Total run 17'-7"
Diagonal stringer length... 21' 5-3/16" (bare minimum)

And it's still an illegal staircase... and kind of tiring and dangerous to navigate. Especially carrying something.

mntnvew 04-14-2009 09:51 AM

Landing?
 
What is the min. landing size allowed for safety and code?

I guess it is my only real option to go with a landing, then I can cut the 20' 2x12 boards into half and use them for the stairs and I only need to get the lumber for the landing itself. I think someone mentioned 3 foot was the min length, so I am looking for confirmation I guess.

I was going to go with 42" wide stairs, is 3 stringers enough? I saw something else about this but didnt understand if 3 was or was not enough.

Thanks again all.

PS - Ron - Thinking is how you get to an end result :)

RegeSullivan 04-14-2009 11:35 AM

You really need to check your local code requirements if that is a concern. Communities can adopt different standards. My previous home was in a community that required any outdoor stairs to be 48” wide if more than 2 steps required handrails on both sides and any stair over 72” wide required a handrail in the middle. Seems like overkill to me but those are the rules in that community.

The number of stringers will depend on your tread material. If you are using 2x it is not enough. 3 stringers on your 42” wide step gives you about 20" OC with a 1” overhang. 16" OC is the max I would go on stairs. 20" OC might be safe but you would get a lot of give (deflection) when walking up or down and it would be compounded by having a stringer in the center because you will tend to use the middle until are to old any need to use the hand rail. 4 stringers gives you about 13.3” OC so you can use 5/4 or 2x. Composite lumber would probably call for 12” OC but I think you would still be O.K.

Cutting your 20 footers in half is not an option even if you do the landing and keep the treads to 7.75 inches. You will still end up short. 7.75" treads will seem really uncomfortable to navigate over that distance and height outdoors with your. If you will only use these stairs for emergencies or very rarely you might be want to keep it 7.75”. I know the minimum for a landing but I try to keep them the same as the stair. In you case the landing would be 42” x 42” if you continue or 42”84” if you make it a return staircase.

I had to open my tool box to find this or I would have put it in my first reply. This rule of thumb was given to me by an “old guy” 35 years ago scratched on to a steel square. Now I’m the old guy… “Tread to rise - add two risers together and subtract that from 25, this gives you the right depth of the tread + or minus an inch.” So if you have a 7.5” rise (7.5” x 2 = 15). 25 minus 15” = 10. Personally I would keep the rise closer to 7” and the tread closer to 12”. You would be surprised what just a ¼ inch will do to the way stairs feel especially on a rise. I did not see it mentioned so I just wanted to say not to forget about the importance of a 1” overhang on the nose of the tread. This should not be included when calculating the tread depth.

You seem concerned about minimums and I have built lots of thing to the minimum requirement because of money or space even on occasion just because I get lazy. One thing each of those projects had in common was at some point in the future I wished I had done it a little better even when I was doing it for someone else.


Rege

47_47 04-14-2009 11:42 AM

Quote:

Originally Posted by RegeSullivan (Post 259737)
“Tread to rise - add two risers together and subtract that from 25, this gives you the right depth of the tread + or minus an inch.” So if you have a 7.5” rise (7.5” x 2 = 15). 25 minus 15” = 10.
Rege

My uncle told me the exact same thing.

Willie T 04-14-2009 11:45 AM

Most of the information you'll need can be found here:

http://www.stairways.org/pdf/2006%20...C%20SCREEN.pdf

Scuba_Dave 04-14-2009 12:05 PM

Many stairs that I see built have 3/4" down as the rough stairs while construction is going on. They then add 3/4" finish wood on top of this. That's 1.5" of wood & very little deflection with 3 stringers
I used 3 stringers on my deck stairs & they are 48" wide
One one side there is maybe a 1" overhand of the stringer
So 23 - 2.5" = approx 20" OC
I used the heavy duty stair treads = 1.5" thick
I carry 80 lb roofing bundles up without any deflection

A deck will last a long time, make sure you build it to last
I went 12" OC for my deck joists for added support

Local codes can be stricter

mntnvew 04-14-2009 12:06 PM

I live in RURAL Montana, i have NO CODES for my barn at all. However I have 2 children, 5 and 9 and I want them to be safe when using the stairs, as well as myself and wife.

I want to spend what is needed, but it is a barn deck.

Thanks All!

mntnvew 04-14-2009 12:09 PM

Quote:

Originally Posted by Scuba_Dave (Post 259747)
Many stairs that I see built have 3/4" down as the rough stairs while construction is going on. They then add 3/4" finish wood on top of this. That's 1.5" of wood & very little deflection with 3 stringers
I used 3 stringers on my deck stairs & they are 48" wide
One one side there is maybe a 1" overhand of the stringer
So 23 - 2.5" = approx 20" OC
I used the heavy duty stair treads = 1.5" thick
I carry 80 lb roofing bundles up without any deflection

A deck will last a long time, make sure you build it to last
I went 12" OC for my deck joists for added support

Local codes can be stricter

I have 2x6's for the treads, that should be nice and thick to deter deflection.


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