don't quite understand the mounting of these condensers

Paul S_3

I just opened my business this past year and I'm getting some commercial work. ...These plans for the "equipment support detail" is what I don't fully understand. ...The vibration isolators that I'm using are the neoprene type that look exactly as they do on the plans which I understand fully. ...what I don't is the 12 gage steel equipment rail....The part where the vibration isolators connect to (marked "ST")....and the 4" steel square tube.....can I just lay the 4" steel on the roof? Thanks Paul S

RobG

I would drop an RFI in the mail to the GC and the engineer. Also check with the vibration isolator rep / manufacturer on the rails, they should know. You will have to coordinate with the roofer as well.

Ironman

The engineer wants the load to bear upon the bar joist, not the roof deck. That's SOP and proper engineering.

EBEBRATT-Ed

My interpretation is he wants 4" square tube sitting on the roof deck spanning the bar joists. Bottom of the isolators bolted to the square tube. (how do you get your arm inside 4" sq tube, could be drilled and tapped) with a steel channel "equipment rail" bolted to the top of the isolators. The condensing units sits on the equipment rail. To really do it right you would post up off the bar joists through the roof deck. The roofer an flash and seal the posts and then set a channel/angle or Hbeam frame on the posts. Then you never have roofing issues.

To set it on the roof deck you can buy equipment rail supports already mad for the roofer to flash in.

The engineers design seems to be more complicated than it needs to be, what else is new?

EBEBRATT-Ed

On second thought the equipment rail he refers to could be part of the condensing unit

Paul S_3

Thanks guys ....what can I use for the equipment rail supports ? Can I use these steel beams and cut to size? Paul S

EBEBRATT-Ed

See pg. 21 of attached for equipment support rails. Page is marked #33 in catalog

Tinman

I think it just invites potential problems to actually incorporate the rails into the roofing. There are so many high end equipment rails on the market now where they just set on the roof.

I'm not talking about treated 4x4's. I'm talking vibration absorbing, canted rails with a wide base and narrower top.

Google equipment support rails and you'll get a ton of hits. That doesn't mean the architect or GC will sign off on any of those options but it may give you options going forward.

Tinman

I don't know how the other guys feel, but I leave the roofing up to roofing professionals, which I'm not. If they want the rails incorporated into the roof, I would just supply them and mark locations and let the roofer do his thing.

On a lot of these "newer" roofs, if somebody other than the original roofing contractor makes a penetration and attempts to flash/seal it, the warranty is voided.

RobG

This is why god invented RFI's, put the onus of responsibility where it belongs! Every time I use common sense some engineer tells me that it's not how he wanted it.

Empire_2

Put a cap on the "G" in god Robert........:-)

Empire_2

The way I see it,...... They want 2 -12ga steel rails to connect the condenser to the 12 ga rail, then the 4" Bar, spanning any (2) joist is the load bearing according to the builder. That 4" square tube must encompass your 2 rails connected to the condenser. With the Vibration Isolators of course. The 4" bar stock or tube must be square in order to equally disperse the load where ever you choose as line as it's spanning 2 joists.
But then I digress and refer back to Stephen and RobG...... "Dammit Spok,......I'm an HVAC guy not a Roofer"!!!!!!!!!!