New Steel Addition over an occupied existing building

[Heldbaum]

Hi,
A new one story addition (penthouse and elevator extension) is proposed over the top of 4-story building. Do any of you know where I can find any restrictions on erecting steel over a building that is occupied during the day ? One of GCs said 2 floors below shall be empty by code or heavy duty roof protection (300psf) to be installed when the floor below is occupied..What if erection takes place at nights and weekends..? I'd appreciate any thoughts or references.

 

[dhengr]

Heldbaum:
OSHA may actually have something on mattes like this steel erection over occupied space. Then there is always common sense, self (financial) preservation on the GC’s and erector’s part, the risk they are willing to take, and what their insurance companies have to say on the matter. I would certainly think you would want to clear out the area and floor level immediately below a given work area for a day or two at a time. This will take some fairly close coordination, communication and planning, and some real help from the bldg. owner to get the bldg. tenants to cooperate. Night work for the heavier items and lifts may make sense. Heavy columns and beams could act like an arrow going through a roof slab, while light stl. jsts., decking and misc. iron work might raise some dust if dropped but probably don’t require an empty bldg. below. You could give some consideration to how much the roof slab could take in the way of a dropped load to make this determination. Some cities have code sections on public safety and protection during steel erection.

 

[Lomarandil]

I'll be following this thread -- curious what you come up with.

----
The name is a long story -- just call me Lo.

 

[Once20036]

I haven't read it yet, but I came across the following article about an expansion over an existing/fully operation facility and thought you might be interested:

https://www.aisc.org/globalassets/modern-steel/archives/2009/12/2009v12_expansion.pdf

 

[Heldbaum]

Thanks guys. I will get in touch with architect and GC and we will figure out something.