Do I need a third stringer for my deck stairs?
stratford1
straight answer on this. I'm using closed outside stringers spaced 36"
and will use metal tread brackets to attach two 2x6 treads for each
stair. Some info I've found says I DO need a third stringer in the
middle for support...others have suggested I DO NOT need a third
stringer as long as my span isnt longer than 36". Any suggestions on
this? Will my 2x6s hold up ok or should I do the third stringer
regardless to make my stairs stronger?
Mikepier
> On Sun, 10 Aug 2008 21:56:06 -0700 (PDT), stratford1
> However my steps are one solid 2x12, not two 2x6's. Of course I only
> have 2 steps because the porch is only about 2 feet high.
>
> 36" is narrower, but you're using 2x6 which is much weaker. I doubt
> they will break from normal use, but if your friends are 300lbs (or
> more), or you intend to move appliances on them, I'd add the middle
> stringer. Or just add one anyhow because you'll have stronger steps.
> The cost is not that much more unless your steps are going up 15 feet
> or so.
A 2X6 maximum span is 24" , so you definately need a 3rd stringer.
I have 3 stringers on my deck stairs and the treads are 5 feet wide.
Phil Again
Did you ask you local building inspector's office if they have any
spacing requirements for stair stingers?
Phil
Art Todesco
My 2 deck steps are about 4' wide using
2 - 2x6s for each step with the
stringer supports about 3' apart (6"
overhang on each side). I've never
noticed a problem in their 20 years of
existence. If I bounce my 200
pounds in the middle of the step, I can
feel a little .... a very little, give.
I never even gave it a thought until I
read this email.
Jim Elbrecht
If you were using 2x12 Douglas fir or yellow pine for treads I might
say OK---
But using 2x6's, likely 'white wood' from the borg, you're nuts if you
don't protect yourself from a personal injury or a lawsuit by adding a
stringer.
Jim
Chip C
A few years ago I was building a deck with steps very much like the
OP's, except using 2-by cedar and with wooden cleats under the ends of
the steps. Doing it to code, permits, inspectors, the works. Local
code very specifically said 3' of 2x material was ok with no stringer.
When I took the permit app in I deal with a couple of older guys who
seemed to know what they were doing; one of them drew a line down the
middle of the steps and said, "you need a stringer there". I said code
didn't say so, and he said, "yeah, but it'll bounce, put in a
stringer." So I did. Lot more work, since the steps were faced onto
the two side stringers I hadn't done any of the design work on cutting
risers and steps out of a stringer (it was a non-stock rise/run), and
had to get a cedar 2x12. But it made a nice job.
Bottom line: if you're wondering about, put it in. Bouncy steps will
leave a shoddy impression in people's mind, even if the rest of the
job is top-notch, and designing a stringer for a custom stair is an
interesting and satisfying exercise.
Chip C
Toronto
Robert Allison
My rule of thumb is that I don't leave a 2x6 unsupported less than
2' OC. If it were me, I would put in the middle stringer and be
happy with the stiffer stairs. If you want to eliminate the middle
stringer, then go with 2x12 treads.
Try this; take a couple of 2x4s and lay them down on some flat
concrete spaced 36" apart, outside to outside. Lay a 2x6 across
them cut at 36". Now step on the middle of the 2x6 and see if you
feel good about the flex. If you do, then go and get about 50 lbs
of groceries in your arms and step on it again. If you still like
it, ask your wife to step on it with you. If you still like it,
then go for the unsupported span. If you don't, add the middle
stringer.
--
Robert Allison
Rimshot, Inc.
Georgetown, TX
Phisherman
Sounds wide, I'd use a middle stringer.
Harry K
So why are you debating using one? The cost of adding a third
stringer is minimal and you already know in your mind that without it,
it will be 'springy'.
Add the third stringer. It won't need any fancy cleats, etc, just cut
to fit under the treads.
Harry K
stratford1
Thanks for all the input! Yes, some of you are asking the right
question...why am I set against not doing the third stringer, since
its minimal cost and work to add it and will make it more safe? Well,
originally I wasnt crazy about the asthetics of having the third
stringer visible between my steps, since they will be spanning from
closed stringers on the ends and will not have a riser board attached,
but its not the end of the world. An injury on my deck would be MUCH
worse. Anyway, thanks for all the help!
sdur...@augustusenergy.com
>
> - Show quoted text -
I struggle with this issue from an engineering perspective and I'm
hoping another engineer can set me straight.
Deflection of a simply supported beam with a concentrated load is: y=
(F L^3) /(48EI)
Using an L/480 stiffness criteria gives an allowable deflection of 36"/
480 = 0.075"
A standard 2x6 has an I = 24.1 in^4 and E = 1.6 e6 psi
Therefore the allowable force on a SINGLE 2x6 would be: 2975 lbs !
That's a 10X safety factor for a 300 lb man !
Spread the load over two boards and the allowable load would double.
Given these calculations, why would a third stringer be even remotely
necessary?
aemeijers
load. Hence the term, 'springy' feeling. I know from experience that an
end-supported 2x6 3 feet long will indeed flex under a walking man,
probably not enough to be dangerous, but enough to feel creepy.
(temporary construction steps while the thicker pretty custom treads
were safely stored away till us jackbooted thugs were done with the
messy work.)
If I was OP, I'd change the design to either 2 'underneath' stringers
inset from the end, or use the full-width treads with the grooves that
drain water and resist splitting, or use a center stringer. If
appearance is an issue, a dark stain on the center stringer before it is
installed can make it visually blend into the background more when seen
from a low angle. Same trick as painting the rocker panels on a car
black to make it seem sleeker.
--
aem sends...
Rick
<sdur...@augustusenergy.com> wrote in message
news:d43f1df2-5624-4503...@x16g2000prn.googlegroups.com...
Well, for one thing, you're using the wrong axis for the moment of inertia...
sdur...@augustusenergy.com
> <sdurr...@augustusenergy.com> wrote in message
>
> - Show quoted text -
You are absolutely correct.
I had looked it up in a table, which didn't specify the axis. Since I
wasn't sure of the axis I did actually check it with bh^3, which
coincidentally gives 24.1 in^4, which caused me to stop right there,
forgetting of course that the actual formula is bh^3/12 !!!
So correcting my original post, the allowable load on a single 2x6
spanning 36" would be 247 lbs which might be a little close for
comfort.
Thanks for the help.
Rick
<sdur...@augustusenergy.com> wrote in message
news:59af7615-ecbf-40c6...@i20g2000prf.googlegroups.com...
You are absolutely correct.
Thanks for the help.
***What dimensions are you using for a 2X6?
SteveBell
> On Aug 29, 11:24 pm, "Rick" <no...@goodone.com> wrote:
> > <sdurr...@augustusenergy.com> wrote in message
> >
> > news:d43f1df2-5624-4503...@x16g2000prn.googlegroups.c
> > om... On Aug 11, 3:44 pm, stratford1 <jegrimsl...@gmail.com> wrote:
> >
> > > On Aug 11, 9:52 am, Harry K <turnkey4...@hotmail.com> wrote:
> >
> > > > On Aug 10, 9:56 pm, stratford1 <jegrimsl...@gmail.com> wrote:
> >
> > > > > I'm building a set of stairs on my deck and CANNOT seem to
> > > > > find a straight answer on this. I'm using closed outside
> > > > > stringers spaced 36" and will use metal tread brackets to
> > > > > attach two 2x6 treads for each stair. Some info I've found
> > > > > says I DO need a third stringer in the middle for
> > > > > support...others have suggested I DO NOT need a third
> > > > > stringer as long as my span isnt longer than 36". Any
> > > > > suggestions on this? Will my 2x6s hold up ok or should I do
> > > > > the third stringer regardless to make my stairs stronger?
> >
> > > > So why are you debating using one? The cost of adding a third
> > > > stringer is minimal and you already know in your mind that
> > > > without it, it will be 'springy'.
> >
> > > > Add the third stringer. It won't need any fancy cleats, etc,
> > > > just cut to fit under the treads.
> >
> > > Thanks for all the input! Yes, some of you are asking the right
> > > question...why am I set against not doing the third stringer,
> > > since its minimal cost and work to add it and will make it more
> > > safe? Well, originally I wasnt crazy about the asthetics of
> > > having the third stringer visible between my steps, since they
> > > will be spanning from closed stringers on the ends and will not
> > > have a riser board attached, but its not the end of the world. An
> > > injury on my deck would be MUCH worse. Anyway, thanks for all the
> > > help!- Hide quoted text -
> >
> > I struggle with this issue from an engineering perspective and I'm
> > hoping another engineer can set me straight.
> >
> > Deflection of a simply supported beam with a concentrated load is:
> > y= (F L^3) /(48EI)
> >
> > Using an L/480 stiffness criteria gives an allowable deflection of
> > 36"/ 480 = 0.075"
> >
> > A standard 2x6 has an I = 24.1 in^4 and E = 1.6 e6 psi
> >
> > Therefore the allowable force on a SINGLE 2x6 would be: 2975 lbs !
> > That's a 10X safety factor for a 300 lb man !
> >
> > Spread the load over two boards and the allowable load would double.
> >
> > Given these calculations, why would a third stringer be even
> > remotely necessary?
> >
> > Well, for one thing, you're using the wrong axis for the moment of
> > inertia...- Hide quoted text -
>
> You are absolutely correct.
>
> I had looked it up in a table, which didn't specify the axis. Since I
> wasn't sure of the axis I did actually check it with bh^3, which
> coincidentally gives 24.1 in^4, which caused me to stop right there,
> forgetting of course that the actual formula is bh^3/12 !!!
>
> So correcting my original post, the allowable load on a single 2x6
> spanning 36" would be 247 lbs which might be a little close for
> comfort.
The Sagulator sag calculator at
http://www.woodbin.com/calcs/sagulator.htm
(assuming Ponderosa pine) says you'll have a 0.09" sag with a 300 pound
dead load. Of course, a walking person is a live load, so doubling to
600 pounds says the sag will be 0.17". I'm ignoring the second 2x6,
since almost all the walker's weight is on the edge of the front board.
You would definitely be able to feel a step that bounced by almost a
quarter of an inch. Whether you would care is something you'll have to
decide for yourself.
--
Steve Bell
New Life Home Improvement
Arlington, TX
Scott J.
If you have enough nose hanging out over the steps you could add 1 X 8 riser
boards on the vertical face of the stairs. This will cut way down on the
springiness on the outer part of the step. A lot easier than adding a
stringer. I'm an Engineer but I'm also practical and lazy.
--
for full context, visit https://www.homeownershub.com/maintenance/do-i-need-a-third-stringer-for-my-deck-stairs-324459-.htm
Uncle Monster
> replying to SteveBell, Scott J. wrote:
> If you have enough nose hanging out over the steps you could add 1 X 8 riser
> boards on the vertical face of the stairs. This will cut way down on the
> springiness on the outer part of the step. A lot easier than adding a
> stringer. I'm an Engineer but I'm also practical and lazy.
> --
>
[8~{} Uncle Sad Monster
Brad
so you should have 4 stringers...
ItsJoanNotJoann
>
> replying to Mikepier, Brad wrote:
> so you should have 4 stringers...
>
>
>
You're NINE YEARS too late with your 'helpful' post.
Gman
--
For full context, visit https://www.homeownershub.com/maintenance/do-i-need-a-third-stringer-for-my-deck-stairs-324459-.htm
Rod Speed
> Nuts? Its pretty common to spread 2x6s on a 36 inch span on stair treads
Peeler
Speed, the auto-contradicting senile sociopath, blabbered, again:
>> Nuts? Its pretty common to spread 2x6s on a 36 inch span on stair treads
>
> Its unlikely that he hasn’t worked it out in 12 years.
abnormal trolling senile CRETIN!
--
Richard addressing senile Rodent Speed:
"Shit you're thick/pathetic excuse for a troll."
MID: <ogoa38$pul$1...@news.mixmin.net>
cshenk
depends on the load value.
Ed Pawlowski
people over.
micky
>Nuts? Its pretty common to spread 2x6s on a 36 inch span on stair treads
I played 3rd string for the Otumwa Mudhens and I didn't help the team at
all.
cshenk
neighborhood built for a friend of mine. I was sort of 'project
manager' I guess. We did it all with donations so no go-fund-me used.
It took us months but we managed to make it so at all times, she could
use it. It's 46inches wide on the ramp but the rails make the inner
part 40 inches. Even though a 'ramp' it still uses a support like a
stringer. We had a center one and 7 4x4 posts to support the central
stringer.
Workers replacing hot water heaters and other heavy stuff can use it
safely. Electric wheelchairs will not be a problem. She's not heavy
but her electric wheelchair is. Guessing combined may be 300lbs?
bruce bowser
Tekkie©
On Mon, 26 Apr 2021 19:01:30 -0500, cshenk posted for all of us to digest...
>
> Rod Speed wrote:
>
> > Gman <35fce865ae42ff65...@example.com> wrote
> >
> > > Nuts? Its pretty common to spread 2x6s on a 36 inch span on stair
> > > treads
> >
> > > -- For full context, visit
> > >
> https://www.homeownershub.com/maintenance/do-i-need-a-third-stringer-for-my-deck-stairs-324459-.htm
> > >
>
> And a center stringer is advised for long term durability but really
> depends on the load value.
--
Tekkie