Commercial Buildout

[giddonah]

Ok, so I have no problems estimating residential stuff because I know how to build it, but this commercial job I'm trying to write up is a bit of a pain.

1600sqft. It's an inside space of a 4-space building, brand new. They're waiting for the exact placement of some extra drains we'll need to pour the concrete floor (that and the weather to warm a bit). The owner is building the fire walls between this and the adjacent spaces. There are two entrances (front and back) and two huge windows (front and back). So I have a couple questions.

The front of the building is ~20' high and the back is ~15' high. How do I suspend the drop ceiling (at 12')? Do I drop wire 8' in the front all over the place? Also, I know it'll be up to the AHJ, but do the walls normally get anchored at the top, or do the perpendicular walls support each other enough to just drop the ceiling all over and build the walls under it?

[Vector]

My answers are based on my expereince (wiring networks mostly) with commericial buildings. They may or may not be accurate in NY (or anywhere else, for that matter).

The front of the building is ~20' high and the back is ~15' high. How do I suspend the drop ceiling (at 12')? Do I drop wire 8' in the front all over the place?

Yes. There's a perfect example of this I wish I had a photo of. They built the dropped ceiling frame, but then only installed the lights, no panels. So you can see everything.

Also, I know it'll be up to the AHJ, but do the walls normally get anchored at the top, or do the perpendicular walls support each other enough to just drop the ceiling all over and build the walls under it?

The walls support each other. Often the suspended ceiling is seperate in each room, with the height of the ceiling an inch or two below the top of the wall. I've rarely seen the ceiling hung over the walls, and when I have, it's always been a space that was retrofitted after the initial build.

[giddonah]

ah. Thanks Vector. The roof is all steel girders. What's the best way to attach the wire to hang the ceiling?

[Vector]

Sorry, no idea. I generally ran my cables about 2' off the ceiling, nowhere near the roof...

[giddonah]

not electrical wires, the wires for the ceiling frame. How should I attach the wires to the girders to hang the frame?

[Vector]

Sorry, I was unclear. Since I was running electrical, I never got near the roof so I have no idea how the ceiling wires were attached at the top, that's what I meant.

[Rich]

What is the deck on the roof? Metal or concrete? With suspended ceiling most code officials will want the wires at 4' o.c. - the ones I've worked with are pretty particular about placement too. You can twist tie off to open web joists or shoot them onto wide flange beams. You can also shoot into the roof if it's a concrete deck. Just get the appropriate loads for your powder actuated gun.

[giddonah]

It's a metal roof. The owner is adamant about there being NO penetrations in the roof. The roof is setup for a 16ton (I think that's what he said) Rheem unit opening and everything is supposed to go through the ducts. I might have to attach purlins to the girders and wires to them or something. I guess that'll need a call to the AHJ.