Decking/Dust Covers

[BearcatEng2013]

I am a recent grad working for a industrial/commercial design firm and I have a client who has requested our services to design several building components, one which is a deck/dust cover. The owner has yet to decide whether they want the interior walls to support decking for storage or just place a dust cover. I have experience doing storage mezzanines but dust covers are new to me. I was wondering if anyone has had some experience and could explain what these are or show me a detail of what they look like. Thank you in advance for you help.

Adam

 

[dhengr]

BearcatEng2013 :
My Grandma used to have about 1/4" think hard plastic covers on her couch and chairs. If you slouched at all, you slid right off the chair. Is that what they mean? That is a stupid enough and ill defined enough requirement, that you shouldn’t feel dumb for asking them what they really have in mind, when they say ‘dust cover.’

 

[TehMightyEngineer]

Yeah, "dust cover" is far too vague. Nothing wrong with asking the client to provide a hand sketch and notes showing their intent.

Maine EIT, Civil/Structural.

 

[OHIOMatt]

Bearcat2013, you don't happen to practice in Ohio do you? I am thinking that this term is regional. I see it all of the time. It is basically a ceiling over a small space inside of a large manufacturing or storage structure. It is there to simply separate the areas, especially when full height partition walls are not used. There is some risk involved in this as people will store things on any flat surface. We typically use light gauge joists with plywood (be careful of building type as this more than likely will need to be FRT). We design the system for a nominal load of say 20 psf and then post that the area is not to be used for storage.

 

[TehMightyEngineer]

There is some risk involved in this as people will store things on any flat surface.

So true. For industrial columns and beams we always have an extra load due to the fact that people always load up your structure in ways you never considered. If you put something up in an industrial setting they'll find a way to abuse it.

Maine EIT, Civil/Structural.

 

[BearcatEng2013]

OHIOMatt, yes I am practicing in Ohio. What you have explained is what I initially thought but needed to hear from someone else. I appreciate everyone else who also responded. Just a little background into this project, it is a warehouse for overhead door sales with a few rooms in the same structure which have walls that do not go completely to the top of the building such as office and restrooms. Like I previously mentioned the owner has yet to decide whether they would like to use the top of the rooms as storage or leave empty. I will definitely follow-up with my contact to verify their definition of a dust cover. Again thank you.

 

[racookpe1978]

Hmmmn.

Indoors? Ohio? (Snowbelt, nasty winters, nasty summers, rain and humidity, right?)
Industrial facility, but with office spaces inside?

So, when (not "if" but "when") an office worker starts storing "just papers" on top of the (conveniently inside, conveniently covered) boxes of papers (each 50 lbs, each stacked on storage racks carrying 12 or 15 boxes hitting the "dust cover" at only 4x legs per rack) just what final load do you expect will happen?

Even if a warning sign is painted on the "roof" of the cover, do you think people will leave a nice, flat, heated, covered inside space un-filled?

 

[Sawbux]

Why not just put suspended ceiling system there? It will be self policing!

 

[CELinOttawa]

Hahaha. I really love the suggestion of suspended ceilings. I'm going to have to remember that!

For sure it will be stacked to the roof with crap. I refused to design an interior space for less than storage load when I worked down in New Zealand. The job of doing the interior layout was left to another engineer. I've never heard how it went during the recent series of EQs, but I *know* that the structure would have collapsed if they stored stuff on it. Makes me want to go door knocking the next time I'm down NZ way, but I suppose that isn't very professional of me. *smirk*

 

[RHTPE]

I had the wonderful experience of checking what was once a shop tool crib recycled as a mezzanine inside of a warehouse. The intent was to use it for file storage. The warehouse manager thought nothing of it until an anonymous phone call (from one of the warehouse employees) was made to the local building official. Upon his visit, the 'plan' was quickly condemned - I can't imagine why.

The remedial work needed to strengthen it to a 250 psf storage load was far beyond any savings realized by recycling the crib. In addition, the original crib was too wide to fit a flatbed trailer so it was cut into 3 pieces and welded back together once moved to its new location.

I agree with everyone else who says design it for storage load appropriate for what can fit. I went with a 5 ft depth of paper which is substantially heavier than anyone in management would have expected. This same warehouse manager also saw no problem with storing bagged cement product on a rack whose main beams had a span of about a 10 ft - when placing a pallet of product on the rack it collapsed and pinned the forklift. Luckily no one was hurt.


Ralph
Structures Consulting
Northeast USA