Concrete Stair - Nosing Bars

[slickdeals]

Folks,
What is the consensus on using Nosing bars in risers for concrete stairs?

We have an ongoing debate in the office that these nosing bars do more bad than good. One school of thought says that the nosing bars are there to provide T&S reinforcement for the risers.

 

[kslee1000]

With good details that ensure proper installation, I prefer to see a nosing than not. For apperance, as well as protecting the sharp concrete corner (tip). Never heard nor thought of that it can be counted as T&S steel.

 

[Ron]

Nosing is good to prevent concrete spalling and excessive wear. Don't count as T&S reinf.

Make sure it is non-slip nosing.

 

[slickdeals]

Maybe I did not explain it correctly. It is a reinforcing bar used for the nosing.

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./
/___
/
./___

The (.) indicates the nosing bar. I am not talking about a nosing angle. It is a reinforcing bar provided below the nosing.

 

[JedClampett]

We use them and have never had a problem with them. I'd be curious on what type of problems they could create.

 

[civilperson]

They are unnecessary unless positioned at the bottom of the concrete step form for tension reinforcement.

 

[slickdeals]

The argument here is thus:
1. Difficult to place - why place when there is no benefit?
2. When concrete cracks, these bars cause more spalling of the nosing.

 

[bjb]

Also, exterior stairs in cold climates will be heavilly salted, and the nosing bars will corrode and cause spalling. They are probably exposed to more salt due to their relatively exposed position in the concrete step. With that said, I commonly see them in exterior stairs. One way to deal with the salt induced corrosion is to specify a penetrating breathable water repellant like a silane or siloxane.

 

[kslee1000]

The nosing bar is utilized for construction purpose - to hold the parallel (longitudinal) bent bars together prior to, and during concreting. I don't think it causes cracks, or corrodes, more than other bars since it's farther away from the surface if installed correctly.

 

[dik]

I've encountered too many problems and have repaired stairs with nosing bars... don't use them!

They are difficult to place, cause a 'hard' point at the edge of a stair; this stress riser can cause the concrete to spall off at the nosing... If not placed right, they're subject to chloride corrosion if deicing salt is used.

Dik

 

[jike]

I am in total agreement with dik! This question came up early in my career and we came to the conclusion to never use nosing bars for the reasons outlined above.

 

[slickdeals]

@Dik,
Thanks for the response. I am early in my career and haven't seen many stairs with problems and hence, the question about best practices.

Does anyone have a valid reason to use them at all? Or is it a unanimous N0-NO?

 

[kslee1000]

We don't usually provide any bars in the steps, except when impact protection was called for. For such stair with L shaped bars in every steps, I would provide the nosing bar at the inner corner, the purpose of this bar is similar to the nosing bar in the corbel. Nosing bar shall not be installed alone.

 

[structuresguy]

My current and previous companies' typical stair details both used nosing bars. In 10 years experience, I have never heard of a problem using them, for whatever that is worth. But I am in Florida, where we use very little deicying salts...except maybe in the last couple nights.

 

[slickdeals]

I am in Florida as well, and this debate pertains to our typical details showing nosing bars. I don't think there has been a consensus opinion in this forum and it seems to be a matter of personal preference.

 

[minorchord2000]

Here in AZ where hunmidity is not really a factor, we detail the riser corner with a #3 bar 1" clear in from both sides. If you use proprietary nosing inserts, you will not need this bar. The proprietary nosing inserts effectively protects the concrete from spalling. The #3 bar on the other hand will reinforce the tip and hopefully keep it from cracking along the edge. No bar will help if the concrete tip gets dinged by some heavy piece of machinery which causes an ugly spall. That's when I call my friendly SIKA rep.