# Air-conditioning ducts get in the way of suspended ceilings



## mikey (Jun 19, 2014)

Seems to be a growing disregard by building services designers of the fact that a ceiling will need to be installed below their ducts somehow. We are working on a school project just now and 85% of the ceiling area is covered by duct work which stops me from getting fixings into the concrete at the required centres. Some spans are 5 metres plus!!

What is the correct thing to do in this situation? How do I get something to hang my dropper rods off?

G'day from Aus


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## chris (Apr 13, 2011)

mikey said:


> Seems to be a growing disregard by building services designers of the fact that a ceiling will need to be installed below their ducts somehow. We are working on a school project just now and 85% of the ceiling area is covered by duct work which stops me from getting fixings into the concrete at the required centres. Some spans are 5 metres plus!!
> 
> What is the correct thing to do in this situation? How do I get something to hang my dropper rods off?
> 
> G'day from Aus


 If height isnt an issue ( duct work being too low ) you can make a cradlel to tie your wires to.Ive seen guys use an upside down main or steel stud


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## McCallum and Sons (Nov 3, 2013)

Hang the wires down from the ceiling and wire up a stud to span the duct and then tie your wires to the stud to hang below for your ceiling. That is what we do in Oklahoma, it may be different if you have any kind of seismic requirements. I think that's the same thing Chris said, you can also use a main.


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## endo_alley (Nov 2, 2013)

Yes, called a trapeze.


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## nodnarb (Apr 25, 2014)

endo_alley said:


> Yes, called a trapeze.


Thats what we call them down here.


I dont know how you bid that job but id do my best to get them to compensate time and materials on that chit.. that or have them hire a duct man to get it out of the way and see who is cheaper!


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## MrWillys (Mar 10, 2014)

Depending on the project you may be able to write a request for information, and get the architect to provide direction. In most cases CRC (cold rolled channel) is used with metal studs being used for longer spans. You can also splay opposing wires which is easier. Check the USG website for further accepted methodology of subject matter. We were never allowed to use mains for trapeze support in California.


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## boco (Oct 29, 2010)

Whats holding up the duct? If they used threaded rods and uni strut you may be able to tie in there. If you could get a pic that would help.


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## mikey (Jun 19, 2014)

chris said:


> Ive seen guys use an upside down main or steel stud





McCallum and Sons said:


> wire up a stud to span the duct


Yes, this is what I'm thinking but the fire-rated lining board weighs 20 kg/m2 (44lb) so the project manager is watching me like a hawk to make sure my structure can support the weight... and not sag!



endo_alley said:


> Yes, called a trapeze.


Well, I looked in my toolbag for some skyhooks but I think I used them all up on my last job 



nodnarb said:


> get them to compensate time and materials


That's the stupid thing. They never submitted the ductwork plans to me at quoting stage and now they're saying just put in a variation and we'll work it out but they never do. They screw you every time.



boco said:


> Whats holding up the duct? If they used threaded rods and uni strut you may be able to tie in there.


Ha ha... the air-con guys are saying "dont touch our threaded rods or supporting structure because it's only designed to hold up the ducts" so maybe we need some discussion at design stage to install ducts and duct structure that can support the ceiling as well.

I've told the builder he'll have to put up a structural steel framing suspended from the concrete slab above which will cost them an arm and a leg .

I have also contacted a couple of ceiling manufacturers here in Aussie to see what they can come up with.


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## keke (Mar 7, 2012)

when I have a problem like this I will go with hilti anchor and heavy duty steel stud to build the bridges :thumbsup:


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## keke (Mar 7, 2012)

endo_alley said:


> Yes, called a trapeze.


we call it a bridge here


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## mikey (Jun 19, 2014)

keke said:


> when I have a problem like this I will go with hilti anchor and heavy duty steel stud to build the bridges :thumbsup:


Thanks keke.

Do you just make a decision what size stud to use or do you get some professional advice? This builder is very picky.


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## keke (Mar 7, 2012)

mikey said:


> Thanks keke.
> 
> Do you just make a decision what size stud to use or do you get some professional advice? This builder is very picky.


you have just 2 options:65 or 90 mm stud but because builder is very shifty(for this reason he didn't send you all the plans) you might want to have a meeting with him and the architect and send them back to engineer for his advice .In this way they will change original plan and you get your extra coins 100%


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## endo_alley (Nov 2, 2013)

If you need a lot of strength just get some unistrut, some all thread, and some steel hangers. Usually upside down Rigid X main works fine.


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## MrWillys (Mar 10, 2014)

See page 10 here:

http://www.oshpd.ca.gov/boards/hbsb/meetings/20120110-meeting/KPFF%20Memo%20(email).pdf

These are requirements for California hospitals! Nobody can possibly be more stringent.


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## mikey (Jun 19, 2014)

Thanks everyone. Your comments have all been very helpful and I'm confident I can get the builder to cough up the $$$ on this one now.


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## keke (Mar 7, 2012)

mikey said:


> Thanks everyone. Your comments have all been very helpful and I'm confident I can get the builder to cough up the $$$ on this one now.


you're welcome Mikey 
don't forget to keep us up to date and post few pics :thumbsup:


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## nodnarb (Apr 25, 2014)

mikey said:


> Thanks everyone. Your comments have all been very helpful and I'm confident I can get the builder to cough up the $$$ on this one now.


Good deal. I ran about a dozen trapezes today, hope you get your money.


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## eurobound (Oct 11, 2013)

I feel for you - we don't have it quite as bad but it took until the 13th floor of a hi-rise to get a ceiling grid that everyone was happy with - dealing with sprinkler guys, ducts, cooling units in the ceiling as well as 2 access panels per unit, gas lines for range and dryer and p-traps from kitchen islands above coming through the floor and crossing the ceiling below... as well as the electrical wires, potlights and fans. 9' slab to slab and the drop ceilings are at 7'8"

I'll post some pics later...


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