Concrete Slab on Grade Stair
Concrete Slab on Grade Stair
(OP)
I'm curious to know how others do this -
A site detail for concrete stairs (not connected to the building):
Do you allow the stair to be 'floating' without foundation walls. Any particular added details for this (I'm used to option 2 typical detail)?
I could see the stairs being subject to movement from frost but so is the abuting side walk. Would you tie the sidewalk into the stairs or let them float individually?
Is this generally acceptable?
or
Do you provide foundation walls/footings around the perimeter of the stairs down to frost and tie the steps into the walls (fill with non-frost susceptible material)?
A site detail for concrete stairs (not connected to the building):
Do you allow the stair to be 'floating' without foundation walls. Any particular added details for this (I'm used to option 2 typical detail)?
I could see the stairs being subject to movement from frost but so is the abuting side walk. Would you tie the sidewalk into the stairs or let them float individually?
Is this generally acceptable?
or
Do you provide foundation walls/footings around the perimeter of the stairs down to frost and tie the steps into the walls (fill with non-frost susceptible material)?






RE: Concrete Slab on Grade Stair
RE: Concrete Slab on Grade Stair
Mike McCann
MMC Engineering
RE: Concrete Slab on Grade Stair
RE: Concrete Slab on Grade Stair
RE: Concrete Slab on Grade Stair
Thanks for the replies.
EIT
www.HowToEngineer.com
RE: Concrete Slab on Grade Stair
How far may do you think the stair base will move?
What is the stair length?
RE: Concrete Slab on Grade Stair
RE: Concrete Slab on Grade Stair
1) Tie the stair to the building at the interface. For the sake of your own liability, I don't think that you want to encourage differential movement at the threshold.
2) For the most part, let the stair float. With the connection mentioned in point #1, I guess the stair is sort of cantilevering off the building.
3) I've seen folks detail some rigid insulation beneath the stair for a couple of meters off the building. I believe that the intent is to trap some building heat and prevent heave right adjacent to the building. I'm not sure how effective this is in practice.
The part that I get stuck on is what happens right at the threshold. Theoretically, if you get frost heave at that location, the upward force on the connection tying the stair to the main building will be extreme. A good argument for the insulation and/or non-frost susceptible back fill I suppose.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Concrete Slab on Grade Stair
Although I would agree with the non-susceptible fill at stairs connected to the building.
Thanks again though for the thoughts.
EIT
www.HowToEngineer.com
RE: Concrete Slab on Grade Stair
RE: Concrete Slab on Grade Stair
If you ask, why not let the stair float? Well I suppose because it could move and it could crack. Well so can the sidewalk. I think if you can assume the stair may crack some but will as a whole remain intact and can be subject to some movement then maybe you don't need the frost walls. I think it would be important to toe in the bottom to help prevent sliding or creep over time (maybe?) and also have a landing at the top of the stair that is integral with the stair. This prevents any differential movement with the adjacent sidewalk that might cause a tripping hazard.
Again this is for a stair NOT ATTACHED TO A BUILDING STRUCTURE.
EIT
www.HowToEngineer.com
RE: Concrete Slab on Grade Stair
My feeling was the key at the bottom is only to prevent sliding so I will keep it at 1'-6". I will add dowels to the top expansion joint to prevent tripping.
Thanks!
RE: Concrete Slab on Grade Stair
Go ahead and use lots of rebar. I hate that stuff but I hate it more when that rich guy who paid me cheap is calling me back every week because his little garden stairway is cracking up.