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Non-Load Bearing Partition Wall Top Connection

Non-Load Bearing Partition Wall Top Connection

Non-Load Bearing Partition Wall Top Connection

(OP)
We have a project with non load bearing wood partition walls on and under wood trusses. We detailed the Simpson Connection that would support the wall out of plane, but had vertical slots to allow for deflection of the roof and floor trusses, so the non-load bearing walls would not become load bearing. The arch/contractor has come back and said this is not standard framing and want it removed from the drawings set. I know in a house you would just attached the non-load bearing wall. This is a 3 level multi use (retail, office and residential). What is your opinion on needing and/or using the vertically slotted top connectors for non-load bearing walls in what application and in what types of buildings. Thanks in advance.

RE: Non-Load Bearing Partition Wall Top Connection

I would defer to the truss manufacturer, who will likely require it. That way you aren't the bad guy...

Unless their trusses can handle the point load from the partition walls, and you have a load path below the partition walls that can handle it.

RE: Non-Load Bearing Partition Wall Top Connection

I would ask for it. Even if the truss manufacturer says they will design the truss for the third support point, you now have to design the floor framing to take that load.

RE: Non-Load Bearing Partition Wall Top Connection

I would not require the slide clips. The contractor is correct--this is not typical in wood construction. And if a non-load bearing partition tries to accept some load, is there really a problem? I have not heard of any issues (such as cracked GWB) in this type of structure.

DaveAtkins

RE: Non-Load Bearing Partition Wall Top Connection

I have seen too many small problems with multistory residential & commercial traced back to this specific detail (more properly lack of detail). I have even seen a couple of nasty failures (trussed roof & floors), requiring extensive repairs.
I would recommend you get the truss manufacturer involved. Between the two of you, the argument is MUCH better.

RE: Non-Load Bearing Partition Wall Top Connection

I will disagree; you absolutely need the truss clips at the top of the partition walls or some other way to brace the walls without letting them take load. This is very common for multilevel wood buildings in my area. You must brace your walls and they cannot be loaded up by the trusses. A single 2x4 stud in a partition wall cannot handle 3 levels of load, even with minimal tributary area. Woodworks has a seminar about this very issue and how to properly deal with it.

RE: Non-Load Bearing Partition Wall Top Connection

It is not common practice, but it is "best practice". The detail will prevent ceiling cracks due to differential movement, but it won't cause a failure.

Trusses won't really pick up the extra support since they don't have a node there. If a non bearing wall hits between 2 nodes in a bottom chord, the chord will flex and not transfer as much load.

You can CYA by saying, "okay you don't have to do it, but don't come back to me with any drywall cracks in walls or ceilings".

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

RE: Non-Load Bearing Partition Wall Top Connection

I would leave it as you have it. Load goes to stiffness. The "non-load bearing wall" doesn't know that it's not load bearing. With all of that said, I agree with Manstrom, it's best practice. Sometimes in these situations I email the contractor (so it's in writing) that they can do it how they want to, but I would recommend the other way. Then, if anything ever happened (in a serviceability sense) then I would point to the email and say, I didn't recommend it, and it wasn't a life safety issue so I gave them the option. In my opinion, it puts the liability on the contractor, and I'm OK with that.

RE: Non-Load Bearing Partition Wall Top Connection

Some additional thoughts:

-In the past, I worked in a market in the US where the slip connections where unheard of. No problems.

-I now work in a market where the slip connections are common place. So I take advantage of that.

-I worked for the wood truss council of america for a while and the only reported problem that would crop up was roof trusses actually lifting connected walls up into the air. Nifty.

-I'm skeptical of the argument that says that bearing walls won't end up at points of truss stiffness. Walk through a building in progress and you'll see all kinds of situations where non-bearing walls fall within a foot or so of truss bottom chord panel points. With floor trusses, your panel points may only be 14" apart so it becomes quite impractical to try to dodge them.

-As structural engineers, we love do drone on about how wood structures are redundant in all kinds of miraculous ways that, thus far, remain unaccounted for. Gap your non-bearing walls and a lot of that redundancy goes away in my opinion. Just sayin'...

@Manstrom/njlutzwe: with these written disclaimer emails, are these situations where the contractor is also your client? I would hate to find myself having to explain to an owner/architect client why I gave the contractor the liberty of choosing a construction method that led to shabby building performance.


I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Non-Load Bearing Partition Wall Top Connection

@kookK, great question.

Most of the time it's been in design build, where I work for the contractor. If I was working for the owner, I would inform the owner and let the owner make an educated decision. I would tell the owner that they paid for it and I recommend it, but if you want to ease up on the contractor and aren't worried about it, that's fine.

With that said, I only do this with what I deem to be serviceability issues. In those events, when I am working for the contractor it's his or her call. For example, I could argue it's best practice to design a floor for L/480 live load deflection to keep them from being bouncy, but the contractor may not care. It's not a code requirement, it's not a life safety requirement. The contractor can tell me he wants the code minimum and it's totally ok. It may not perform as well as the L/480 floor, but that's their call to make. Same with slab-on-grade control joints. I show a location that works. If they want to change it up, by all means, go for it. Ultimately, the contractor can decide on some of those things if I'm working for them. And, in reality, the owner is part of that decision, albeit passively. If you hire a contractor for design build, you do it assuming you want the bare minimum, except where you specify elsewhere. Contractors aren't in the business of giving things away, and owners know that. So if they want it designed based on best practices, they probably aren't going the design build route.

Just my two cents. I'd love to hear your response and how you deal with these issues.

RE: Non-Load Bearing Partition Wall Top Connection

Great summary njl, thanks for providing it.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Non-Load Bearing Partition Wall Top Connection

(OP)
emmgjld - do you have pictures of a place I can get some pictures of such issues???

RE: Non-Load Bearing Partition Wall Top Connection

On a job right now where some kind of connection as described above may have prevented the excessive deflections at the tip of cantilevered mezzanine joists supporting a "non-bearing" wall hard-framed to the underside of roof members.

RE: Non-Load Bearing Partition Wall Top Connection

I have seen a similar detail cause some fairly significant issues. In one case, a high end two story home had roof trusses that loaded a non-load bearing wall to the point that it caused notable and excessive localized deflection in the floor below. The contractor (also the homeowner) built the walls tight between the trusses before installing the concrete tile. The fix for this situation was not simple. I would definitely say this is best practice and even an essential practice if you anticipate significant dead load. At the very least, installing the non-load bearing walls after most of the dead load is added would help the situation. Although, I know this is not how they would build it.

RE: Non-Load Bearing Partition Wall Top Connection

I have never worried about in wood construction. As KootK mentioned, the only issue I have ever witnessed is the truss picking up the wall.

RE: Non-Load Bearing Partition Wall Top Connection


Greatone76;
I will look. The best/spectacular failure was in 1977, I may still have photos.
Most cases I have seen do not photograph well & many other excuses are produced, clouding the issue. Too many times our expansive & collapsible soils are blamed for any cracking or structure movement.

In my experience, most cases are related to heavy (tile) roofs & heavy (tile or concrete surfaces) floors. Complicated trussed roofs seem to factor in. The problem has decreased some since the mid 90's, when the trusses were 'better' designed (better programs), constructed better (better equipment) and the snow loads in Colorado were better appreciated in some of the low load areas.

RE: Non-Load Bearing Partition Wall Top Connection

We have seen problems for commercial, multi-level construction, where no provision was made for floor deflections above non-structural partitions. The biggest effect we've noticed is service-level cracking of wall finishes and floor at these levels. For that reason alone, we ALWAYS detail for floor and roof movement independent of the partition walls (while providing for bracing them at the top, of course).
Dave

Thaidavid

RE: Non-Load Bearing Partition Wall Top Connection

After reading through all of the comments on this thread I am no more the wiser on this subject, it seems like the opinion on how to handle this sort of thing is all over the place with no overall consensus.

Logically it would seem to me that the slotted connectors would allow for relative movement, would that not increase the likelihood of the GWP cracking?

A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com

RE: Non-Load Bearing Partition Wall Top Connection

So long as the drywall contractor provides little isolation joints between the top of the partitions and the ceiling it theoretically works fine, but looks a little weird. It they don't, you probably get cracking worse than you might get from no gap. I think it really comes down to local practice.

RE: Non-Load Bearing Partition Wall Top Connection

I'm with thaidavid40 on this one. I've seen it crack up drywall in several multistory buildings, so we always provide a detail showing the slotted truss clips at partition walls.

RE: Non-Load Bearing Partition Wall Top Connection

Greatone76;
Just my luck, the file contains 2 copies of every report, inspection report and even the report of the floor truss engineer, who handled everything well, except the plumber with a Sawzall. But the photos are gone.

The issue was 3 floors, constructed with 2' high floor trusses, each capped with 3" of concrete and a trussed roof. The interior walls were framed tight and the issue in 1 structure was apparently excessive deflection of the roof hip masters, with the problem telegraphing to the lowest floor.

The other 3 structures had much the same problems, but 'minor' installation issues, minor manufacturing deficiencies and the occ. plumber with a Sawzall resulted in a BIG repair.

RE: Non-Load Bearing Partition Wall Top Connection

We live in a litigious society, riddled with construction defects. I know that arena reasonably well.

I want to address njlutzwe's summary to KootK's comments, without regard to the merits of a slip connection or not......

For us design professionals, if we put a requirement in the plans or specifications, and subsequently a building permit is obtained based on that information, it becomes a building code violation to deviate from the plans and specs (administrative section of the International Building Code and its state variants.....yes, I know it's routinely violated!!). There is a procedure, rarely followed, for resubmittal of changes by the design professional. These are usually just done on the fly.

Fast forward a few years when construction defects become evident (also more likely to manifest in wood framed structures early on).....lawyers get involved and an investigation of the design and construction ensues. Chances are that there is no paper trail available to the investigation team at the time because of legal discovery rules and legal civil procedure. Each party hunkers down and rallies its cause, without respect to any of the other parties.

The investigation gets done as reasonably as practicable with given information and field investigation. Sometimes analysis is done, sometimes not depending on the legal process. The investigation team reaches a conclusion that the in-place construction is different than shown on the plans and specs. Then the assessment has to be taken to a different level of cause and effect. As you can see it spirals downward with higher investigative costs and legal costs until the real answer (hopefully) is found.

So fundamentally, if you put a requirement on your plans or in your spec, enforce it. If you are waffling on putting it in, follow the standard of care of your area for design professionals.

RE: Non-Load Bearing Partition Wall Top Connection

Ron,

Thanks for your comments. Please provide the admin code reference location in IBC. I am not familiar with it. As for my area, and I would guess most areas, things during construction change all the time. By your analysis, it seems to me as though you would have to resubmit to the permitting office every time there was an RFI or a small field tweak. In all seriousness, where would it end?

RE: Non-Load Bearing Partition Wall Top Connection

Double edged sword

Require a best practice detail like this and avoid potential serviceability problems down the road. Cost of construction goes up. Get branded as the engineer who requires expensive details. Lose clients.

Don't require the detail and let them build it using conventional typical construction practices. Possibility of serviceability problems down the road. If problems occur and fingers point back at the engineer, then we should have known that this was a bad detail. Lose clients.

It's lose-lose

Option 3 - "recommend" the detail as best practice. Let the owner / builder make an educated decision and put the ball in their court.

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

RE: Non-Load Bearing Partition Wall Top Connection

Njlutzwe,

Technically yes. But like Ron said, nobody ever does it, and most jurisdictions don't care. It is more or less left up to the design professionals to decide when a change is big enough to let the Building Dept know about it.

Manstrom,
I like your option 3, but I suspect a moderately competent lawyer will argue that you should have known better and not left it up to the owner who is a poor uneducated fool in these matters.

RE: Non-Load Bearing Partition Wall Top Connection

Manstrom, I agree.

dcarr. Good points, but ultimately you can get sued for anything. I say you do the best you can and don't stress about it. Every litigation case I recall hearing about was some ridiculous there is no way it could have been prevented.

I'm not going to live my life worrying about getting sued. I'll do what I can to prevent it, but ultimately all lawyers can dream something up that I didn't think of. That's outside of my control.

And no matter what option you pick, a lawyer could pick you apart. Let's say that you choose to require they install the clips. Then, the contractor does it reluctantly, does a poor job and there are still issues. You get dragged into a lawsuit because they didn't install them correctly. You say, you showed a detail that was correct but they didn't do it that way. Then, the lawyer says, "well, yes that's true, but you knew it wasn't standard practice for them, you should have made sure they did it right". You say, that wasn't in my scope. The lawyer says, "yes, but given the circumstances." You argue the letter of the law, your insurance provider is still scared, they settle, you pay the deductible.

Point is, do the best you can. You dream of a way to not get sued and a lawyer will come at you another way...

RE: Non-Load Bearing Partition Wall Top Connection

I place a detail on my sheets that shows the deflection connector.

During the crash, I did a fair number of home investigations for owner's that were trying to dump their properties. Home inspectors locked onto excessive floor deflections and drywall cracking and typically came to us with concerns about the foundations. Most problems I encountered were on stick built multistory wood, and the vast majority of them were from a floor loading a demising wall loading and then the demising wall loading a floor (or floors) below. You would get drywall cracking as drywall panels experienced shearing/racking. You would get pronounced humping of the floor below sometimes with degradation of the floor finishes. I have never experienced any issues with trusses and demising walls.

If contractors push back on my detail as "non-standard" construction, I will write an email to the Architect (to be forwarded to the owner) that explains the potential consequences of providing a hard connection. I then let the owner and contractor hash out what they want to do. So long at the expected consequences are related only to serviceability, I look at it as a question of funding and tolerance to defects on the part of the owner. I also think that if I ever expect this to become "standard" construction practice in my area, then I have to be a catalyst of change.

RE: Non-Load Bearing Partition Wall Top Connection

This is a minor side point but I'm curious to know the answer anyhow. If you use standard stud heights at the bearing walls such that studs do not need to be cut then the gap detail will mean non-standard stud heights at the non-bearing walls. Is that of any consequence economically?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Non-Load Bearing Partition Wall Top Connection

For anyone who typically specifies the slotted deflection clips, what model are you using for floor trusses? Do you use them at every truss? I can't seem to find one that has more the 70 lbs capacity with a 1/2" gap (Simpson DTC). If I use standard 5 psf loading for a 9' wall I need clips at about 3' o.c. Wondering if there are any that would work at 5'+ to reduce installation cost.

RE: Non-Load Bearing Partition Wall Top Connection

I use the Simpson STCT at each joist/truss. When they are bought in bulk, they are under a dollar each, so I don't ever worry about the installation cost.

RE: Non-Load Bearing Partition Wall Top Connection

Thanks Mike. Any idea why Simpson doesn't post capacities for that clip, even thought their installation notes say to use that one when the truss is gaped from the NLB walls?

RE: Non-Load Bearing Partition Wall Top Connection

I've always done my slip joints this way. Screw a plate to the underside of the joists above. Build the wall on the floor such that when stood in place there is the desired gap between the wall top plate and the plate on the underside of the joists. The contractor then has to go and drill entirely through his top plate. He then has to provide screws/nails long enough to go through the wall top plate, bridge the gap, and penetrate the plate on the underside of the joists enough to provide the capacity needed laterally.

It sounds more complicated then it is. The only cost difference between the non-load bearing and load bearing walls is then the labour for this connection, and the longer fasteners. No galvanized connectors are needed. That's what bothers carpenters the most, additional hangers that cost money.

RE: Non-Load Bearing Partition Wall Top Connection

One way to avoid the issue of slip joints is to design the floor or roof framing to have less deflection. Of course that runs the costs up as well.
Most issues I see with multi-story wood structures is excessive floor deflection.

RE: Non-Load Bearing Partition Wall Top Connection

This is an issue that I have dealt with recently, and now on a new project I would like to include a detail to gap the top of the interior non-load bearing walls below the roof truss bottom chords. My question is how to handle installation of the drywall ceiling and wall panels to prevent crushing of the drywall at the ceiling/wall corner when the trusses deflect? There obviously needs to be a gap between the top of the wall board panels and the bottom of the trusses. How can this be accomplished? Fur down the ceiling panels? Attach a piece of crown molding to the ceiling but not the wall? I admit that I know very little about sheetrock installation. Anyone have any advice or a detail drawing that you wouldn't mind sharing?

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