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Concrete stairs in hillside.

borgward's picture

I need advice about constructing concrete stairway in hill side. 5" rise, and 12" run. 9 treads 48" wide and 4" thick w/ 4" wide beams at each side. Do I need to use rebar, or wire mesh?

I have not to decided to excavate steps into the hillside, and pour over them (sand between concrete and the soil), or excavate a slope under the stairs. I think a flat slope would better isolate the stairs from the underlying soil that has a high shrink swell factor. What keeps the concrete at the top stair from flowing down to the bottom of the stair during the pour?

(post #106409, reply #1 of 19)

Should we assume there is a 48" frost depth to deal with?  Or more?


 

(post #106409, reply #2 of 19)

No Frost

(post #106409, reply #3 of 19)

you start from the bottom and work your way up. thats what keeps the concrete in the top step from flowing down to bottom during the pour.


i would use wire mesh to reinforce it with, and you should have a few (maybe 6?) postholes dug as footings or piers to give the flat on the bottom concrete structure some purchase on the hillside.


where are you? 

(post #106409, reply #17 of 19)

>where are you?

>>Central Texas

>>Where are You?

(post #106409, reply #18 of 19)

i am in missouri

(post #106409, reply #19 of 19)

where are you?

(post #106409, reply #4 of 19)

I need advice about constructing concrete stairway in hill side. 5" rise, and 12" run. 9 treads 48" wide and 4" thick w/ 4" wide beams at each side. Do I need to use rebar, or wire mesh?


I'm confused, is it 9 @ 4" = 36" for the total rise, or 9 @ 5" = 45" total rise?


See, for exterior stairs you want taller rises, 8"-9" typically.  If you use a "half-height" rise, you need twice the tread distance (think 24" deep).


You definitely want to have a "footer" at the top and bottom of the stair unit "cutting" into the undisturbed soil of the hill (you use dowels, rebar lengths, to keep sidewalk or patio slabs at top & bottom from "floating" out of alignment).


You will hate trying to bend woven wire mesh into stair forms.  It also won't do very much good to strengthen the steps, either.  I'd run a #4 bar 12" in from each side, and one in the middle, and "ladder" that with a 36-42" #4 bar @ 12" O.C.


When you order/mix the concrete, you want a very low slump mix.  If you are mixing this, that means not very wet at all (but wet enough, concrete is zen like that).  You place the concrete from the bottom step to the top.  Your formwork will have boards for each riser, but not the treads. 


So, you load in from the bottom step until it gets level to the tread, then you start loading the next step up.  This will "want" a specific sort of pacing--and you will be able to tell, it will push out from lower treads if you go too fast, or with too loose a mix.  If it does, lay off more work for a bit. 


You will want to review the code in your area, you may need to have this inspected before pouring.  You may need railings on one or both sides, too.  If you need railings, go and size them now, so you can get sleeves in place before pouring (it's 10x easier before, and 100x easier with this all being a thought exercise--don't ask me how I know).


Occupational hazard of my occupation not being around (sorry Bubba)
I may not be able to help you Occupational hazard of my occupation not being around (sorry Bubba)

(post #106409, reply #8 of 19)

>I'm confused, is it 9 @ 4" = 36" for the total rise, or 9 @ 5" = 45" total rise?

>>I was thinking concrete 4" thick when I get to the side walk from the bottom of the stairs to the house. Now that I think about it, The depth of the concrete in the steps is going to be more than 5" The Rise is 5"

>See, for exterior stairs you want taller rises, 8"-9" typically. If you use a "half-height" rise, you need twice the tread distance think 24" deep).

>>In any case, that is a moot point, as due to existing restraints at the site, 5" rise and 12" is what works, and that's what feels comfortable to she who must be obeyed.

>>We went to the state capitol where she showed me a variety of stairs that worked for her. I was surprised to find a lot of stairs on the grounds that were way out of standard, but were easily traversed. There was no uniformity from one stair to the next. Those stairs date back to the mid 1880's. I wonder where the 17" number came from. I hear it from a variety of sources

>you want a very low slump mix.

>>How low, what slump do I ask for, low being relative to who you are talking to.

>You will want to review the code in your area.

>>No code or inspection here.

(post #106409, reply #10 of 19)

>>We went to the state capitol where she showed me a variety of stairs that worked for her. I was surprised to find a lot of stairs on the grounds that were way out of standard, but were easily traversed. There was no uniformity from one stair to the next. Those stairs date back to the mid 1880's. I wonder where the 17" number came from. I hear it from a variety of sources


Yeah, I'm not finding my landscaping reference (naturally), but the 17" number is almost always an interior value.  And then there's a note off somewhere that you use a larger value when outdoors.  ADA-compliance moots almost all of that, making for generally awful stair runs.  I've always used 8" rise dimensions as a planning point (it courses with masonry and is generally "modular" for design purposes).


I've also been subjected to a number of atypical exterior stairs and walks, too--cusrt eve'y one of them, too <g>


But, if the Design Committee hath spake, then She must be obeyed.


>>How low, what slump do I ask for, low being relative to who you are talking to.


If ordering redimix, I'd ask for 2" and let them talk me into 3" and be very stingy with water on site.  You might could ask for "curb mix" (meaning the batch mix made up to cast curbs).  I'd probably only use form oil on the riser front form boards too (although brownbagg might disagree with me there, and he's much more a pro at 'crete, too).  I've seen some hands trying to place curbs with 10" slump "soup"--felt uniformly sorry for those hombres every time, too.


>>No code or inspection here.


Well then, that's good and bad.  Good in that you need not go pull permits or wait on inspectors.  Bad in tha


t some contractors in the are may be used to "getting away with" various things.  Have you thought of, decided upon a railing for these stairs, you are in the neighborhood of a 4' grade change only 5' deep, and some sort of railing seems apt, that being around 40º or so of slope.


Occupational hazard of my occupation not being around (sorry Bubba)
I may not be able to help you Occupational hazard of my occupation not being around (sorry Bubba)

(post #106409, reply #11 of 19)

>ask for 2" and let them talk me into 3", could ask for "curb mix".

>>Thanks, been a long time since I've dealt w/concrete.

>railing for these stairs?

>>No. but I appreciate the advice. We've been walking a plank from the drive to the porch for about 5 years. Besides I do not want to obscure the view of the front of the house. These stairs will be a luxury. Will take it up the old Kazoo if I have to add handrails later. I know, I know.

(post #106409, reply #12 of 19)

When you are excavating and forming these stairs allow for a minimum of 4" of concrete below the intersection of the back of the tread and the bottom of the riser.
Run rebar (3-4 pieces ) down the run of the stairs from top to bottom in that 4" space. Elevate the bar so it is at least 1 1/2" off the sub grade.
Also drop a piece of bar into the treads, perpendicular to the run of the stairs, about 2" back from the nose and about 1" below the tread surface.


They can't get your Goat if you don't tell them where it is hidden.

Life is Good

(post #106409, reply #13 of 19)

Will take it up the old Kazoo if I have to add handrails later.


BIt of post hole work and a pvc sleeve now could save much effort later, is all.  Well, ok, probably three sleeves, tob, bottom, and middle, but still, cheaper now than a core drill rental later . . .


Occupational hazard of my occupation not being around (sorry Bubba)
I may not be able to help you Occupational hazard of my occupation not being around (sorry Bubba)

(post #106409, reply #14 of 19)

Sounds reasonable. Guess I could plug the hole w/ some grout on top of paper.

(post #106409, reply #15 of 19)

Use PVC female threaded fitting at the top of the sleeves. Screw flush caps into the fittings that you can remove later on.

Or, Use a flush adapter to an inspection plate cover and use a metal inspection plate that you can remove later on.


They can't get your Goat if you don't tell them where it is hidden.

Life is Good

(post #106409, reply #16 of 19)

Guess I could plug the hole w/ some grout on top of paper.


Well, with a PVC sleeve, I'd probably use an inspection cap (flat, not domed) and set in silicone adhesive rather than solvent glue.


Grouting the hole works, but you wind up needing something threaded through the grout plug to cleanly yank it out, and whatever that "is" hangs out in an untidy way until used in my experience.


Occupational hazard of my occupation not being around (sorry Bubba)
I may not be able to help you Occupational hazard of my occupation not being around (sorry Bubba)

(post #106409, reply #5 of 19)

Cap'n brings up the size issue.  Normally, the formula for sizing steps is "twice the rise plus the run equals 24 to 26". 


Whatever your rise is, the formula doesn't work for 12".


 

(post #106409, reply #6 of 19)

Rise and run should equal 17-1/2" to 18". 12" 5" = 17" That is close enough. I quote the AIA Architectural Graphic Standards Sixth Edition page 7: "riser plus run = 17" or 17-1/2" ".

Is there a different standard for outside stairs? Please quote source.

In any case, it is a moot point, as due to existing restraints at the site, 5" rise and 12" is what works, and that's what feels comfortable to she who must be obeyed.

We went to the state capitol where she showed me a variety of stairs that worked for her. I was surprised to find a lot of stairs on the grounds that were way out of standard, but were easily traversed. Those stairs date back to the mid 1880's. I wonder where the 17" number came from. I hear it from a variety of sources

(post #106409, reply #7 of 19)

Sorry, I'm backing out in favor of someone whom can quote verse better than I. 


 

(post #106409, reply #9 of 19)

Sorry, notification of your reply came to my mail box before the Captains did, even though he replied before you did.