Stairs Behind Tall Walls 3

[CANeng11]

In design of tall walls, do you ever take into account any support from stairs or landings behind the wall?

 

[r13]

No. Unless you have design the stair/landing to support the wall.

 

[jittles]

Only as a very last resort.

 

[jayrod12]

Agree with the above, tall wall or none, I design stair openings as just that, openings. So when you have a two storey house, you have to pay attention to the details of the wall supports at the floor levels. Same thing for the basement wall when there are long openings directly against the wall.

 

[r13]

I would like to add to my note above - Even you have designed the stair to support the wall, it is a very dangerous proposal, as it is not a common practice well known to other engineers/professionals. The stair may subject to alteration, or demolition, while the wall remains in service, at that point, no one would know it was designed to be a structural support until bad thing happens.

 

[jittles]

I'm going to disagree with retired13's last post in principle. It's always the responsibility of whomever is modifying a structure to make sure that it meets code and is structurally safe after an alteration. I don't think it's defensible to assume some sort of "common practice" and then neglect checking the modified structure properly.

 

[jayrod12]

I would tend to agree with R13s post from the thought that when it comes to removing a stair, most contractors I know would rip it out without a second thought. Many "minor renovations" where I practice are done without an engineer's involvement. And by the time someone were to realize the issue and call an engineer it may be too late.

 

[jittles]

I see the point ya'll are making, but I still don't think it's defensible from those contractors' perspectives.

Seems like a slippery slope if you start trying to consider all those sorts of possibilities.

From what I see, "common practice" is rarely common or uniform across all engineers, contractors, markets, etc.

 

[jayrod12]

Oh it's not defensible. Yes they'd be liable. Doesn't make everything better just because someone is found liable.

Why even leave that as a possibility, unless like you said a last resort. But if you're designing a new wall, why not just design it appropriately.

The whole thought of "oh that's the next guy's problem" is also a slippery slope.

 

[r13]

At the closure, I can only say I won't speculate who is ultimately responsible in failing of the wall under the court of law. But, if I am called to the witness stand and asked: "Is a stair supporting a wall a common engineering practice?", my answer would be "No." "Is a wall supporting a stair a common design practice?", the answer would be "Yes." When I say "common practice", it meant a usual understanding/knowledge that is well known, accepted, and commonly shared in the engineering universe, construction practicing contractors included. Precaution is required when deviate from the common practice, otherwise it is liking a bomb, we don't know who is the victim when it explodes.

 

[dhengr]

Mas745:
And, maybe we should design all beams to span two column bays, just in case some dummy takes one of the columns out. Certainly, a bearing wall could be removed because some genius with a hammer and a pick-up thinks it isn’t a bearing wall. If we start designing for things to counter what some dummy might do, there is no end to that escalation. You just can’t protect them, us and the whole world from all their stupidity. When they alter a structure, without proper engineering help, they should know what they are doing, and that they may be operating at their own risk, if they don’t understand all the details. Obviously, in today’s world, this does not protect us from someone else’s stupidity, but it should not prevent use from taking advantage of every possible reaction system in the structure, if we wish. I also understand that there is some merit, for minimal cost, to design around this potentiality.

 

[IRstuff]

But, again, there are common practices that are used in construction, and homeowners and contractors depend on that. Otherwise, every remodeling job would require an engineer to review plans to determine whether the designer did something unexpected. That would be good for SEs but it would kill 90% of most home remodels.

I'm currently going through that right now, because there are a couple of shear walls that need to come out, so I'm paying an engineer to come up with an alternative. But if every wall had "hidden" structural features, I'd have to stop doing anything, since that would increase costs by 50%.

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[r13]

Purely for entertainment only, let's image listening conversations among the owner, contractor, and the engineer.

Owner to contractor: "I've an outage coming up soon, and I would like to free up the space at the stair by the wall, and move the stair closer to my new equipment at the other location. How long it will take, and how much it will cost?"

Contractor: "No big deal, I've done it many times, but you need an engineer to design the new stair as I wouldn't be able to do it."


Owner to the engineer: "Well, how fast you can come up the design, and the costs?"

The engineer: "Well, after initial investigation, the stair can't be removed as it is a structural support for the wall. In order to relocate the stair, I'll have to perform further analyses to understand the relationship between building framing and the wall, and may need to modify both the wall and the frame to make up the lost of a support. It will take a while for the complexities involved, I'll sent you an estimate ...."

The Owner: "!!!!!?????xxxxx..."

 

[jittles]

But, again, there are common practices that are used in construction, and homeowners and contractors depend on that. Otherwise, every remodeling job would require an engineer to review plans to determine whether the designer did something unexpected. That would be good for SEs but it would kill 90% of most home remodels.

Any alteration of an existing structure should be looked at by an engineer, I don't see how you can justify it any other way. I routinely do this sort of investigation for home remodels for competent contractors.

The engineer: "Well, after initial investigation, the stair can't be removed as it is a structural support for the wall. In order to relocate the stair, I'll have to perform further analyses to understand the relationship between building framing and the wall, and may need to modify both the wall and the frame to make up the lost of a support. It will take a while for the complexities involved, I'll sent you an estimate ...."

The Owner: "!!!!!?????xxxxx..."

More like, Owner: Well thank goodness we did it right and hired an engineer to look at this and didn't just assume some asinine "common practice". That could have been a disaster!

 

[r13]

The owner continues: "By the way, to save some time and cost, can you utilize the light poles and downspouts along the wall....?"

Engineer: "It is uncommon, but if ....."

 

[jayrod12]

Any alteration of an existing structure should be looked at by an engineer, I don't see how you can justify it any other way. I routinely do this sort of investigation for home remodels for competent contractors.

Must be nice to have contractors and owners want to pay for your services where you practice. Where I am, many contractors will try to talk an owner into modifying their remodel intent to avoid bringing on an engineer where possible. We're seen as the enemies who just add costs to the project, both fees and material costs. And that's not just our firm, that's region wide (and from my experience almost country wide).

How do you ensure that those calls happen for all renovation projects? Are you cruising around looking for renovations being completed and then checking for permits etc? Not trying to be an ass, just pointing out that the ideal world of engineers being called for every alteration is unrealistic. And therefore you should be designing in general conformance with standard construction and design practices. Are there situations where you need to go outside the box? Of course. Is this one of those situations? Not in my mind.

 

[BridgeSmith]

There's a difference between the need to hire an engineer to look at an alteration to a structural component (like making an opening in a wall), and hiring, or even knowing that you need to hire, an engineer to make an alteration to something that typically does not require an engineer's review (a stair).

Forgive my ignorance on this subject, but I'm a bit confused as to how a stair would be expected to provide support or bracing to the full length of a wall, anyway. Won't there be portions of the wall that the stair doesn't support? And wouldn't the wall need to be designed for those unsupported sections? If so, wouldn't it be more trouble than it's worth to have different sections of the wall designed and constructed for different conditions?

Rod Smith, P.E., The artist formerly known as HotRod10

 

[jittles]

jayrod12, it's probably important to note that I practice in an area with heavy snow loads, high seismic (SDS = 1.0g), high wind (V=130 mph minimum in town, up to 160 mph as you go up the hills towards the mountains), and a stickler of a building department on top of that.

The city is actually known for driving around and trying to find work going on that doesn't have a permit posted in a visible location.

As to the original question, I've never actually had to go so far as to use the stairs to support a tall wall, but I have seen a couple of projects by other engineers that have done stair walls utilizing the stairs, stringers, landings, etc as part of the supporting structure for the walls. The detailing and framing was awkward, far from the norm, and probably expensive, but it was apparently their best or only solution in those cases.

 

[Aesur]

The way I see it is removal or relocation of a stair would be an Alteration level 2 per IEBC. For this an engineer should be hired to review the change. If the stair was used to brace a wall, then an engineer was originally involved, and therefore this is a custom house, not a tract home. In this case, the owner/contractor "should" know to hire an engineer as it was most likely designed per the IBC and not the IRC. I have been involved in very few custom homes that meet the requirements of using the IRC. This is a common issue I see, where a draftsperson is hired to do the design work for a new or a renovation to a custom house and they use the IRC when the IBC should be used, and unfortunately few plan reviewers in my neck of the woods seem to catch or question this for houses. I have seen contractors/draftspersons remove lateral systems without consideration and it actually got permitted. I have been called in to do renovations to larger commercial work that had contractors formerly remove lateral and gravity systems without consideration. We as engineers seem to be the only ones trying to make it so the others involved don't have to think by trying to consider every possible outcome. It's not practical nor possible to consider every possible future for a project. ie. a forest is used to classify wind exposure as B... will that forest always be there, or the building that was used.. why not design everything as C.... We have to stop doing the contractors job, they are the only ones with increasing profits because they no longer have to think.

 

[r13]

Right or wrong, the owner and the contractor will laugh at you when you mentioned the need to investigate the entire building structure to ensure the safety in removing a stair from the building. Surely the laugh will stop when they find out the hard way, and no matter win or loss, the designer will be called to testify with reputation put into question. What a mess caused by deviation like this from common engineering practice and care.