# HVAC ducts run under (not in) the slab



## Vanadium (Oct 8, 2017)

My condo I have learned has the HVAC ducts run underneath the slab, directly in the dirt. They're run in galvanized steel. I learned this when I started to smell mildew and tracked the smell to my vents where I learned they had decayed since they're directly in the dirt and come in direct contact with the ground water.  Now the water gets directly into my HVAC vents because they're decayed to the point of disintegrating.

I am wondering if this is something that is not in code now but was at the time of construction?  My place was built in 1979.

Thanks for any help!


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## cda (Oct 8, 2017)

Welcome

That is a new one

Give it a day or two for replies


What does your HOA say???

You must not be the only one with the problem


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## cda (Oct 8, 2017)

Well after looking apparently it was done in the past ??


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## Mark K (Oct 9, 2017)

Notify your HOA and the members of the HOA of the problem.  Your focus should be on identifying the scope of the problem and what are your options to fix it. 

I believe that some subterranean ducts are still being used in some situations.

There is a good chance that there are other buildings that have had similar problems.  You want to find these buildings so you can better understand the problems..  You want to find a mechanical contractor or mechanical engineer that was around in the 80's who is familiar with this type of ducts.

The HOA should check with their attorney but given the time that has passed it is not very likely that you could recover the costs.

The reality is that you really do not need to be talking to building officials until you have a plan of action to fix the problem.


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## steveray (Oct 9, 2017)

Still allowed by code, have a church doing it now....Not the best idea IMO, and usually not done correctly, but allowed.

603.8 Underground ducts. Ducts shall be approved for
underground installation. Metallic ducts not having an
approved protective coating shall be completely encased in a
minimum of 2 inches (51 mm) of concrete.


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## Vanadium (Oct 9, 2017)

Thanks for the replies.  The HOA is aware of the issue and has told me the responsibility is all mine. 

I have had 2 HVAC contractors come look at it. Both said it was too decayed to do any repair and the only solutions they had were to plug the existing vents with concrete and run brand new vents through the ceiling - which basically will involve ripping out my entire floor and be a massive expense for a house that doesn't cost much and I planned to sell next year anyway...

Other units have the same problem and the HOA has also told them it's the owner's problem to deal with.

As for the 603.8 code, I don't feel like any special protective coating was used - it looks like standard galvanized steel - and they are definitely not encased in concrete, so I feel like they are NOT in code.  Is it possible this code was different in 1979?


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## Vanadium (Oct 9, 2017)

As I write that, I guess the process of galvanizing IS the process of making them corrosion resistant, is that correct?


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## cda (Oct 9, 2017)

Vanadium said:


> Thanks for the replies.  The HOA is aware of the issue and has told me the responsibility is all mine.
> 
> I have had 2 HVAC contractors come look at it. Both said it was too decayed to do any repair and the only solutions they had were to plug the existing vents with concrete and run brand new vents through the ceiling - which basically will involve ripping out my entire floor and be a massive expense for a house that doesn't cost much and I planned to sell next year anyway...
> 
> ...




Seems like you would be impacting the hoa's foundation




Not an ac person either but there are the ductless

Not sure how they are installed


http://www.mitsubishicomfort.com/ar...tages-of-ductless-cooling-and-heating-systems


http://www.homedepot.com/b/Heating-...-Splits/N-5yc1vZc4m1?experienceName=technical


And they cannot reline or put a smaller duct inside the existing??


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## Vanadium (Oct 9, 2017)

cda said:


> Seems like you would be impacting the hoa's foundation
> 
> 
> 
> ...



The argument from the HOA is that it is as-designed. If the foundation itself was damaged, that would be their response, but the foundations are not the problem here. The HVAC system is what's gone bad, and the master deed specifically says the HVAC system is the owner's responsibility.

I might look into the ductless options. Can they hook into an existing thermostat somehow? The rest of my house (upper floor, half-basement not under the problem area) are all fine as those ducts are run through the walls/ceilings. So I don't want to have 2 different systems going on here...

I asked about smaller ducts, but the ducts branch off multiple times under the foundation.  In the basement you can see one large ducts go through the foundation wall into the dirt, but somewhere under there it branches out to 5 vents.


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## Paul Sweet (Oct 9, 2017)

Is your condo a townhouse, or more like an apartment?  Where are you located?


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## Francis Vineyard (Oct 9, 2017)

What about the possibility of boxing in or building a soffit around new ducts below the ceiling and against the wall?


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## mtlogcabin (Oct 9, 2017)

https://www.ductarmor.com/


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## Vanadium (Oct 9, 2017)

Paul Sweet said:


> Is your condo a townhouse, or more like an apartment?  Where are you located?


Townhouse. I have a strange split level with 4 "floors" - basement, ground floor, upper floor, and top floor. I'm attached via garages to a neighbor. There are 4 units in total with me on one end.



Francis Vineyard said:


> What about the possibility of boxing in or building a soffit around new ducts below the ceiling and against the wall?


Not my favorite solution, but it's worth considering. Thanks for the idea.



mtlogcabin said:


> https://www.ductarmor.com/


Closest vendor is 2 hours away it seems, but it may still be worth a call.


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## Vanadium (Oct 9, 2017)

Also, I'm in Kentucky.


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## cda (Oct 9, 2017)

Vanadium said:


> Townhouse. I have a strange split level with 4 "floors" - basement, ground floor, upper floor, and top floor. I'm attached via garages to a neighbor. There are 4 units in total with me on one end.
> 
> 
> Not my favorite solution, but it's worth considering. Thanks for the idea.
> ...



Well you are in a better situation being an end unit


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## Rick18071 (Oct 10, 2017)

I don't know alot about them but they do have high pressure systems that use very small ducts.


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## tmurray (Oct 17, 2017)

Check the actual definitions of the bounds of your condo. Generally the HOA owns below the slab.

Also, keep in mind these associations rarely actually know things. They just pretend to. At least in my experience...


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## Pcinspector1 (Oct 17, 2017)

Could install a mini-split system to get by during the litigation phase.


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## cda (Oct 17, 2017)

tmurray said:


> Check the actual definitions of the bounds of your condo. Generally the HOA owns below the slab.
> 
> Also, keep in mind these associations rarely actually know things. They just pretend to. At least in my experience...





It sounds like it is a town home 

Maybe individual lots??

With common areas ??


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## north star (Oct 19, 2017)

** & **

Vanadium,

*IMO, ...a ductless mini-split system will be your*
*"financially favorable option"*......I would seal
completely the existing, deteriorated ducts and
remove & cover over where they enter the various
rooms.

While the mini-splits are an option, they too come
with limitations.......We install a lot of the mini-splits
in to our facilities......While Mitsubishi brand is the
current leader [ IMO ] in these type of units, Trane
also makes a good unit.

Regarding the Mitsubishi brand, we are experiencing
a proprietary control over their units......Their units
require a Mitsubishi licensed & trained technician to
work on them, and currently, ...in the state in which
I am located, ...there is only one (1x) authorized
dealer of the Mitsubishi line and the various parts.
Not just any HVAC contractor can service the units.
That said, we DO still install a lot of them.......They
work very well and are energy efficient.

Also, some of the older thermostats will not work
on the newer mini-split units, Mitsubishi & others.
It is a designed monopoly of the units......They
want to sell Mitsubishi products with their units.
A SIDE NOTE:  A lot of fire alarm systems have been
doing this for quite some time now  [  i.e. - proprietary
design  ].

Just sayin'...

** & **


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## Paul Sweet (Oct 19, 2017)

If it's a townhouse condo it would probably have been built under the old CABO One & Two Family Dwelling Code, if a code had even been adopted at that time.


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