Has anyone run ac ducts under icf slab above I beams? I have an Architect asking for a way to change directions across I beams so need either very thin and wide to go under i beam or under slab 4" slab.

as with any joist/deck floor system (wood or concrete) you can run utilities between the joists but not across them.
dropping down below the joists is required for any large diameter pipe or duct. small diameter pipes or conduit can be placed into (across) the joist before the pour, but only with prior approval by the structural engineer.
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Peter is, once again, dead on. It comes down to how bad you want to do it, and what the exact geometry is. You can run through stems, but it will take a special detail which will have to be specially designed for the application. If it's really important, I could do it for you if you live in one of the states I'm licensed in. Otherwise, if your SE has a problem doing it, have him call me and I can give him some suggestions.

Another argument for split systems as is done in most of the world

one of the cleanest solution to address this condition is to run a soffit along the walls and then to feed the ducts/pipes up into the space between the joist. this creates the look of a coffered/tray-ed ceiling and is applied by many architects when designing volume/high spaces.
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I hear you Peter yes that is "what they want" I'm in NY do you cover that area?

Jay

no coffered ceiling I'm afraid

Jay

Jay,

If Jerry is not licensed in NY, if interested, give me a call, i can get it engineered with a NY Engineers stamp on it. We can also install it if you also need that.

Greg Fasano
ICON Structures LLC
239-438-2670

Sorry- not licensed in NY, but if you have any specific questions, I'll be glad to help you out.

Hi Greg, Sorry for not responding earlier been crazy, I still have the same question coming from all my Architects, do we have anyway of doing this change of direction without coffers? Jay

I just built with Insuldeck and after looking at the problem for a couple years I have come to the conclusion that when working with ICF and Insuldeck, architects need to include utility chases at least perpendicular to the Insuldeck beams. Both Insuldeck and QuadDeck need to talk that up more among their customers. Much more.

Posted By ICFHybrid on 30 Jun 2012 01:13 PM
I just built with Insuldeck and after looking at the problem for a couple years I have come to the conclusion that when working with ICF and Insuldeck, architects need to include utility chases at least perpendicular to the Insuldeck beams. Both Insuldeck and QuadDeck need to talk that up more among their customers. Much more.

That is one of the issues I am  facing in my design phase. Running the ducts in the InsulDeck forms, especially since you have to also run returns on the opposite ends.

How did you end up doing yours?

Soffits.

In some cases we located interior walls before the Insuldeck pour and inserted vertical sleeves that came directly down through the future wall, through the Insuldeck and into the floor below. Those will be ceiling mounted vents.

As a hybrid, it got a lot easier in the wood framed portions.

I thought a lot about how I would do heating duct if I had to, but then I realized that doing forced air heat once you have Insuldeck, seems like a waste.  Insuldeck is all about being an efficient hydronic radiator in the first place.

Posted By ICFHybrid on 30 Jun 2012 04:52 PM
Soffits.

In some cases we located interior walls before the Insuldeck pour and inserted vertical sleeves that came directly down through the future wall, through the Insuldeck and into the floor below. Those will be ceiling mounted vents.

As a hybrid, it got a lot easier in the wood framed portions.

I thought a lot about how I would do heating duct if I had to, but then I realized that doing forced air heat once you have Insuldeck, seems like a waste.  Insuldeck is all about being an efficient hydronic radiator in the first place.

Wouldn't your HVAC duct do both (A/C and forced air heat)?

How big was your ductwork that went through the InsulDeck? You had to do 2, correct (supply & return)?

My ducting was only for ventilation. The whole system was less than 200 cfm as opposed to heating and cooling which is many times more.

I only did supply for the basement areas. The return is the entire stairwell to the basement.

We did it with 4" PVC pipe which is 4-1/2" OD.  It requires a 2 X 6 studwall above.

That is one of the major drawbacks with InsulDeck/concrete flooring. Running ductwork and plumbing can be challenging if not impossible at times. With wood floors it is very easy to run utilities, with InsulDeck concrete, not so much.

designing and running ac/heating systems supply and return chases is very similar to doing it in a 2X wood framed structure.
you can place large chases between the joists, but only small diameter pipes can be run across/through the lumber.
when using wood trusses for the floors its similar to using metal bar joists, and therefor easier to run utilities in all directions.

on a residential project its easy to do if the supplies and returns are run vertically between floors inside of closets or near stair wells. this results in thicker walls which usually dont even get noticed, and the room feeds and returns can be from these vertical shafts, which reduces the need for duct work. with the use of distribution soffits longer runs can be easily accommodated.

but, YOU and the ARCHITECT have to THINK about and DESIGN for it in the planning phase.

if your do not, it will be just as difficult to AC a wood joists framed house as it is insuldeck.
exept for the part of just cutting the plywood floor with a saw.

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Whew! That's a lot of mixed messages there. Yes, large air ducting is going to be similar across construction methods. But, the facts are that it is quite a bit harder to run smaller utilities across the spans of Insuldeck than it is any kind of wood. TJIs have popouts and you can just hog through dimensional lumber, but you have to dig foam all the way, target lightening holes in stiffeners and dive under the concrete "joists" in the Insuldeck.

The industry needs to be more proactive about promoting the use of dedicated chases and runs among ICF designers and architects and provide more resources to the plumbing and electrical service industries.

Posted By insuldeckflorida on 03 Jul 2012 09:53 AM

if your do not, it will be just as difficult to AC a wood joists framed house as it is insuldeck.
exept for the part of just cutting the plywood floor with a saw.

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What is the pitch of your concrete InsulDeck roof?

Are there any vent holes in your roof?

lbear

not sure if your post was addressed to me...
but i do live in a 3500 sf icf house with icf roofs, 15' from the intracoastal...
no, there are no vent holes through the roofs except for the code required waste plumbing stacks...
it is a 65 year old 1500 sf, hurricane destroyed, single story cmu structure, with a new 2 story all icf structure added on after the storms...
essentially the whole envelope is sealed, except for what leaks out around windows and doors.
we took down the truss roof and gutted the old structure to the cmu walls and terazzo floors, and added icf lofts on top of it, all capped with 10" plus 3" concrete insuldeck roofs, some 3/12 pitch, some flat... this portion is serviced by a  2 ton central stack hvac system.

3 years later we added a 2000 sf 2 story, attached icf structure, with 3/12 pitch roofs, including a single car, non-conditioned garage/workshop with loft... all roofs are still raw, smooth concrete, none of it sealed yet, still some work to do...
all roofs have spider cracks in them, no leaks below... slab to wall/stucco/hardie board transtions are sealed with sikaflex.
we still have raw insuldeck panels for all our ceilings, which we will cover with t&g wood eventually...

when u r retired as we are, you need to keep some work for later...
the addition is serviced by a chased, vertically stacked 2 ton hvac system...
minimal duct runs, just wall registers...
if any one wants plans or pictures email me...


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