Interior stud framing 2

[Struct1206]

I have a couple projects going where we keep coming up with the same issues regarding interior stud framing. It's always been my understanding that the interior stud work was basically delegated but I'm finding that it's really just left up to the installer to put up something that "works". In most cases they are installing single track headers over openings regardless of how big they are. This means that most of the openings end up being supported by the track attached to the framing or roof deck above. Which brings me to my next issue, hanging from the roof deck. I've always felt that it was a no-no to attach anything to the deck. I realize that some small loads aren't an issue but as soon as you give permission for supporting a minor thing you end up with 6" sprinkler pipe hung from the deck. So my question is, how much involvement do you guys have in the design of interior stud work (door and window opening framing, bulkheads, etc.)and what sort of limits do you put on attaching to roof deck?

 

[Ron247]

By my way of doing business, my scope of work details what I am designing. I also have a section that outlines what I specifically am not designing. If I am not being paid to do the studs, then I do nothing with the studs beyond relaying any information about the interaction of the studs with what I am designing. For example, the stud wall must be capable of supporting a 400 plf vertical load from the roof. If you are responsible for the walls, then you have to address them. Some stud suppliers have their own engineer.

As far as people hanging things from any part of your design, you would have to spell that out in your documents. Notes on hanging loads are very difficult to outline. Just when you think the notes are clear, a really creative person shows you how wrong you are. I had to go to an plant that had a main control building with a collapsing roof. It was metal building Zs. The drawing stated they could only hang loads off the Z-purlins no larger than 50 lbs. The main aisle was the only place you could hang something with a ladder, so EVERYONE hung their loads in a 5' strip of the roof. One person used 10 attachments side-by-side to hang 400 lbs, next to another person that used 6 to hang 250 lbs etc.

 

[DaveAtkins]

I do a lot of engineering of cold formed steel framing, and the only time I design interior studs is when they carry gravity loads (usually mezzanine loads, occasionally roof loads).

In my experience, drywall contractors understand how to build non-load bearing interior framing, using headers, slip tracks, etc.

DaveAtkins

 

[Struct1206]

Ron - This is what I've done in the past (working for consulting firms) but I work for a full service AE firm now, so if I'm not going to design it we still have to figure out who is and make that clear somehow. At least that's my opinion; would you agree?

Dave - I would agree with your take on the drywall contractors to some extent but at some point their typical window/door framing doesn't necessarily work. Typically, what I am seeing is a single track "header" and doubled up jamb studs at openings (regardless of size). On a current project that's what they are providing on a 24 foot wide by 9 foot tall opening in an 18 foot tall wall. Now everyone is asking me if it works and for me it's a big NO (unless everything is hung from the framing above). Right now it's basically being supported by the top track that's attached to the roof deck which I'm also not a fan of.

 

[Ron247]

Yes, I agree mwhite. Each part of the design needs to be addressed as to who is going to be responsible. We routinely put the design back on a supplier for some items, but we have to make it clear what we expect from them in that regard.

 

[Ceinostuv]

It just depends on the AHJ. Much of what I do is delegated design for interior framing, exterior framing, and non-structural component support. For our interiors, about half of that work is driven because the design team has it listed as a deferred submittal; however, a lot of the larger drywallers we work with will seek out engineering to limit their liability.

That being said, I have to disagree with Dave here. In my experience, the drywallers definitely know how to construct things that are stable but they don't hit the mark when it comes to building something 'up to code.' More often than not, nearly everything is undersized because they pull the sizes from limiting heights schedules and don't read or understand the little caveats within those tables (like notes that require "bracing to develop full moment capacity.") I could go on listing examples forever; but my point is that they know how to build but they don't know how to design/size/detail.

Now for the more controversial part, I also find that there are MANY EOR's who apparently don't understand light-gauge framing themselves. Just as often as I see undersized members in the field, I see undersized members within design drawings by EORs. Heck, I've seen an EOR specify a PAF in concrete to resist tension in a Seismic Category D region; the worst part is the PAF they specified was a Gypsum-board to metal stud fastener and had no loads listed for installation to concrete. It is obvious that to many of the EOR's out there, the light gauge framing and non-structural components are merely an afterthought for them; something you dig into your archives to look for a few typical sizes and details and hope that the plans reviewers don't ask for calculations.

mwhite, if you are not going to do the design yourself, I would implore you to put a lot of thought into creating realistic parameters to guide the delegated designer. The worst projects are when the EOR doesn't communicate what their structure was designed for. The better projects are when the EOR provides some kind of input on how they designed their building and communicate the limitations of their structure (roof deck designed for maximum point loads of xxx @ xxx o/c). The best projects are when the EOR maintains some kind of realistic expectations with those limitations; if one more EOR tells me their structure wasn't designed to support the interior suspended ceiling that has been shown in the Arch. drawings since day 1, I might lose it (please, please, PLEASE, remember that buildings are meant to support more than just their self-weight and live loads).

Judgement-In-Training

 

[Struct1206]

We typically delegate load bearing and exterior cold formed framing design but the interior stud work doesn't get included as it is part of a different spec section. I think going forward we might include some basic framing details and specify limits on wall height and opening sizes for which those details apply. Then we could specify that anything that falls outside of those limits will be included in the delegated design. Does that sound like a reasonable approach?

 

[Struct1206]

Also, does anyone have any thoughts on hanging bulkheads from the metal roof deck? Everyone in the office acts like I'm crazy when I tell them I don't want anything hung from my roof deck.

 

[jayrod12]

I usually have a 5 to 10 pdf allowance in my roof for ceilings and mechanical. Generally the bulkheads and stuff weigh less than that.

 

[Struct1206]

jayrod12 - I agree, I do the same thing but I expect that most, if not all, of those things are connected to the roof framing and not the deck. I don't think it's a big deal to occasionally screw something directly to the deck but I don't want to give the contractors free rein to connect to my deck as they see fit. I'm getting some resistance from the architects in the office and I'm just curious if I am being over cautious or if I should stick to my guns.

 

[Ron247]

Some of the terminology I am not used to. Bulkhead is not a term I see or hear much in my area of the world. What do you mean by the word?

Also, the actual source of the load is not as big a deal to me as the duration and method of attaching it. I assume by metal deck you are talking about a metal deck with something else on top of it like insulation or concrete. I also assume the load is permanent in duration. I can come up with 2 attachments that will support the same load but one could stress the deck more than the other one.

I do not see why you could not attach to the deck provided the deck can safely support the load. But I also feel it is a bad choice to use the deck. The deck can be potentially maxed out in numerous locations. Someone would have to check all these locations because even 50 lbs can finish off a thin metal deck. I am sure the people wanting to hang from it do not want to pay the engineering fee to check all this out.

 

[jayrod12]

I check my deck for at least an additional 5 PSF assumed to be hanging. I generally also assume they'll be using the toggle style hangers.

Is it ideal? no, but seriously your life gets significantly easier if you play ball and just design around it. If you increased the deck thickness to accommodate a slightly higher design load, compared to the fighting and pain and additional analysis required during construction, what is better for you?

I've said the same thing to contractors and clients. They all get on board with that mentality.

Bulkhead is a stick framed, drywalled box to hide services etc.

 

[Ron247]

Thanks jayrod, here they generically call it a "chase".

 

[Ceinostuv]

We typically delegate load bearing and exterior cold formed framing design but the interior stud work doesn't get included as it is part of a different spec section. I think going forward we might include some basic framing details and specify limits on wall height and opening sizes for which those details apply. Then we could specify that anything that falls outside of those limits will be included in the delegated design. Does that sound like a reasonable approach?

Sounds great! Tell your contractors to send their drywall subs this way, having a reasonable EOR makes projects much more enjoyable

Also, does anyone have any thoughts on hanging bulkheads from the metal roof deck? Everyone in the office acts like I'm crazy when I tell them I don't want anything hung from my roof deck.

I wouldn't think you're crazy as long as there is another option to hang framing from.

Thanks jayrod, here they generically call it a "chase".

Are chases usually vertical? That was my understanding of the term, at least. I think bulkheads run horizontal, like a pair of walls hung from above with joists running between them. Can someone confirm?

Judgement-In-Training

 

[Struct1206]

Sorry, I guess there are several uses for the term "bulkhead" and probably better descriptions of what I am referring to. Most of the architects in this area generally refer to a bulkhead as any type of wall that protrudes below their ceiling line. So, in a lot of cases we're just talking about a drywall sheathed metal stud wall that hangs down below the ceiling line from "above". Typically, the contractor will just screw stud track to the roof deck (no concrete fill just rigid insulation) and hang the studs from that. I think this is probably an ok approach in some cases but the weight of that type of assembly is going to quickly outrun the capacity of the screws through the deck.

 

[Ron247]

I agree, chase tends to be vertical but here, they lump them together, everything is a chase to some of them. I have never heard anyone mention a bulkhead here when I was around, but I have heard chase many times.

Also, bulkhead here is more a nautical term for dividing space.