Non-Load Bearing Partition Wall Top Connection

[Greatone76]

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.

 

[emmgjld]

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.

 

[Ron]

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.

 

[Guastavino]

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?

 

[manstrom]

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

 

[dcarr82775]

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.

 

[Guastavino]

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...

 

[RobertHale]

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.

 

[KootK]

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.

 

[BadgerPE]

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.

 

[mike20793]

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.

 

[BadgerPE]

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?

 

[jayrod12]

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.

 

[XR250]

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.

 

[gte447f]

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?