Rebar for small basement stairs supported by wall on both sides

Question

I'm rebuilding small stairs (5 steps) leading from the street to my basement apartment. They are supported by brick walls on both sides, as you can see in the picture.

The old stairs i just demolished did not have rebar yet were very sturdy (the reason I demolished is because they need to go one step below were they went as i lowered the basement floor). What could be the adverse consequences of not using any rebar and just pouring concrete in the form? It's about 30" wide.

Not an engineer - But, I don't think you need full rebar if it's supported properly at the bottom. However, the wire mesh type would be helpful, and a lot cheaper. — Chris Cudmore, Sep 23 '21 at 17:48
Is this a suspended stair, or a stair sitting on dirt (soil)? You would need rebars for the former not the latter. — r13, Sep 23 '21 at 18:16

score 2 · Answer 1 · answered Sep 23 '21 at 17:19

2

The stairs have a greater risk of cracking without the rebar. That may not be a problem if the area behind the stairs is sturdy. I would just use rebar to be sure, as in the long term stair life could be shortened by a 5 or so years.

answered Sep 23 '21 at 17:19

Joe Blowe

259
1
5

I am not sure I would say 5 years. I have seen basement steps with no rebar look new after 60 years. So maybe they would last 100 years and with rebar 105? – DMoore Sep 23 '21 at 19:23
I meant the life will have 5 or so years knocked off of it's life, that means say, 100 years with rebar, 95 years without it. – Joe Blowe Sep 23 '21 at 23:56

score 2 · Answer 2 · answered Sep 23 '21 at 18:45

This is dependent on the type of concrete you use. With a mix that is heavy limestone (the new white stuff everyone uses for driveways) you will for sure need rebar.

If you are using a mix with a lot more aggregate it may not matter or matter enough to worry about it. I have demo'ed 60 year old steps with no rebar so many times and almost all were in great shape. The type of cement they used in the 50-60s was the best in my area and the aggregate/portland blend... that stuff lasts forever with no cracking.

I have also demo'ed 20 year old steps with rebar that the noses where cracking. I am not anti-rebar at all. I am just telling you for steps with support like yours its so far down the list of importance.

Most important things:

Set a good base and stamp it out. I have also see my old-timers add large rocks on each row that top's sit 6-8 below step.
Protect the brick that won't be part of the step. You will need some physical barriers there.
Do not use a limestone mix. Pay extra for more portland. The good stuff for steps is either dark dark grey after mixed or tan/brown aggregate mixed in. I don't care what anyone says - been through this so many times I can eye test how long concrete will last.
Floating the area is crucial and honestly it might be a step above DIY. The top needs to slightly slanting away. Each step needs to have a slight slight slant to the bottom. Each step cannot have a dip near the riser. All of this is more important going to basement steps which tend to take longer to dry out.
If you feel better add some 3/8 mesh rebar to each step. It is kind of like a craft project before your pour. The rebar should float in the middle of your pour. I am guessing you won't be using forms for the sides. So to get the rebar to float and not just settle on the bottom (useless) I have "stuck" the rebar into the high side of the dirt a good 5-8" at the right level and on the other side curl the rebar.

Rebar for small basement stairs supported by wall on both sides

2 Answers2