Dustcover With No Storage

[BSVBD]

The client wants the lightest CFS dustcover ONLY over the offices. This "dustcover", which will be accessible to the adjacent manufacturing facility, we all know, will be a temptation for storage.

IBC specifies an "Elevated Platform" of 60 psf, but, that would increase the joist size and, thus, the price. I also do not see this as a requirement.

In IBC Table 1607.1, Residential has "Uninhabitable attics without storage" for 10 psf with a foot note that clearly defines allowable height restrictions within the attic space, providing reasonable obstacles to justify the space as both uninhabitable and not for storage.

A wide open "dustcover" does not offer any restrictions other than a posting of "Storage Not Allowed".

Does anyone know of either an IBC, ASCE or other enforceable minimum live load for open accessible dustcovers or platforms?

A human could collapse a dustcover with as little as 10 psf live load.

 

[DaveAtkins]

I have used, on occasion, "Scuttles, skylight ribs, and accessible ceilings." The live load requirement is a single 200# concentrated load (presumably to handle one person walking around).

But I have always wondered--there are A LOT of people who weigh >200#...

DaveAtkins

 

[BSVBD]

Yikes! I've never seen that! Technically, my dustcover is an accessible ceiling!

Fortunately, the contractor asked me to used a minimum 6" CFS joist, which DOES support he 200# point. He also stated that the carpenters DO have to fasten the metal deck to the cover, therefore, THEY will be standing on it.

And yes, a LOT of people exceed 200#. Similarly, when we apply the required 200# load to any application, i tend to consider a minimum 250# when reasonable.

 

[Lomarandil]

Dave, just don't specify any bolts pretensioned by turn-of-the-nut up in your ceiling...

 

[TehMightyEngineer]

I'd say between Dave's "accessible ceilings" idea and some signage specifically stating the allowable load, you're all set. I'd design it to support at least a 250 lb person + 50 pounds of tools/excess load and label it in bright yellow "200 pound capacity". Mark your drawings clearly with the live load and make sure everyone is 100% on board with that limit. Should cover you legally.

That said, manufacturing and industrial facilities are the WORST for overloading things. If it were me I'd fight tooth and nail to be allowed to reinforce it for a reasonable 20 PSF or something more substantial. Maybe mention that a lawsuit costs a lot more than a few more more joists.

I can't remember any off the top of my head but might want to also check OSHA to see if there's anything in there that would be required to meet for minimum loads.

Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries

http://www.americanconcrete.com

 

[dicksewerrat]

When you build a space more that 5 feet high, someone will use it for storage. They will put all the paper files generated in the office up there. File cabinets are very heavy 10 - 20 reams of paper per file drawer, 4 drawers per file, 4-5 square feet per file cabinet. 50 psf would not be a stretch.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[BSVBD]

make sure everyone is 100% on board with that limit

That is one luxury i deal with on a regular basis with our mainstream general contractor client - they are a generally reasonable team from design architects, estimators, project managers, expediters to job sup's and site foremen. As stated in my first reply, it was the PM's idea to bump the joists up to 6". As a result, the 6" 20 gage satisfies both a 250# point and a 20 PSF scenario.

We will intend to have sufficient spec's on out plans to cover us.

dick... i recall many years ago being called by a local inspector to inspect a mezzanine that the facility maintenance supervisor (MS) had built without plans or approval. When i arrived on site and met with the MS, he informed me that "you could drive a bus up there". I replied, "I'm not concerned about a bus. Buses are filled with air. I'm more concerned about you stacking paper up there." His facial expression was priceless!