Thread: Gas pipe run in duct

Inspection of a new home had a steel gas pipe run through the center of the range exhaust hood duct. The home was suppose to have a recirculating fan/micro. The buyers wanted it vented to the exterior. The micro mounts to the exterior wall so the duct is very short. When I lifted the exterior damper flap there was a gas pipe running through the center of it. They just notched around it. I called the AHJ dept. and they said it was not allowed. I told my clients what I was told. The builder came back and said the AHJ said it was Ok.
Because of the short run through the exterior wall and is open to the exterior and not a closed system like a air handler, is this allowed? If not what is the code, I know I read it a long time ago elsewhere on this forum I think. If it can not be installed through the duct and it is code can the Local AHJ say it's ok to be there, don't they have to abide by what is written?

Thanks

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Fuel Gas code:
G2415.1:
PIPING SYSTEM INSTALLATION.PROHIBITED LOCATIONS:
: Piping shall not be installed in or through circulating air duct, clothes chute, chimney or gas vent, ventilating duct, dumbwaiter or elevator shaft.

I would confirm with AHJ that he told the builder it was ok.

Originally Posted by Mike Schulz

I called the AHJ dept. and they said it was not allowed. I told my clients what I was told. The builder came back and said the AHJ said it was Ok.

Mike,

The sure fire way to beat the builder on that is to have your client request a letter from the AHJ stating that "it is okay" ... I doubt the builder will get it in writing, *even if* the AHJ actually did tell the builder it was okay - it is one thing for the AHJ *to say* something - there is no real legal standing on what was "said", but to *put it in writing*, then it become their official interpretation, and, if outside code, that means they have overstepped their bounds and become *PERSONALLY* liable, meaning their sovereign immunity is gone.

From the 2006 IRC. (underlining is mine)
- SECTION M1503
- - RANGE HOODS
- - - M1503.1 General. Range hoods shall discharge to the outdoors through a single-wall duct. The duct serving the hood shall have a smooth interior surface, shall be air tight and shall be equipped with a backdraft damper. Ducts serving range hoods shall not terminate in an attic or crawl space or areas inside the building.
- - - - Exception: Where installed in accordance with the manufacturer’s installation instructions, and where mechanical or natural ventilation is otherwise provided, listed and labeled ductless range hoods shall not be required to discharge to the outdoors.
- - - M1503.2 Duct material. Single-wall ducts serving range hoods shall be constructed of galvanized steel, stainless steel or copper.
- - - - Exception: Ducts for domestic kitchen cooking appliances equipped with down-draft exhaust systems shall be permitted to be constructed of schedule 40 PVC pipe provided that the installation complies with all of the following:
- - - - - 1. The duct shall be installed under a concrete slab poured on grade; and
- - - - - 2. The underfloor trench in which the duct is installed shall be completely backfilled with sand or gravel; and
- - - - - 3. The PVC duct shall extend not more than 1 inch (25 mm) above the indoor concrete floor surface; and
- - - - - 4. The PVC duct shall extend not more than 1 inch (25 mm) above grade outside of the building; and
- - - - - 5. The PVC ducts shall be solvent cemented.

- SECTION G2415 (404)
- - PIPING SYSTEM INSTALLATION
- - - G2415.1 (404.1) Prohibited locations. Piping shall not be installed in or through a circulating air duct, clothes chute, chimney or gas vent, ventilating duct, dumbwaiter or elevator shaft. Piping installed downstream of the point of delivery shall not extend through any townhouse unit other than the unit served by such piping.

While that is not really a "circulating air duct", it is a "ventilating duct", in this case it is an "exhaust duct", which is (by definition) a "ventilation" duct.

- VENTILATION. The natural or mechanical process of supplying conditioned or unconditioned air to, or removing such air from, any space.

No, no piping through ductwork period.
Builder is full of BS.
Whenever the builder claims muni insp says it is ok. I ask to see the permit sign-off. They can never produce it.

Originally Posted by Markus Keller

I ask to see the permit sign-off.

Markus,

That is treading into territory you do not want to go.

Next, the builder will be telling you is it all "OK" *because* the permit was signed off. (Which is the logical reply to what you asked for.)

Wait ... they already tell us that ... Nope, you do not want to go there, that would just convince them that the permit being signed off actually means something.

The better way is for the AHJ 'put it in writing' that 'such-and-such is ok' ... in addition to the permit being signed off.

You guy's are great, Thanks again................

Hurricane Ida Took out the air handler that uses all of the ductwork under my house. That same storm told me that it is prudent to move my propane tank from where it is, to the side of the house closest to the road because the water did not reach that far. My question:

Is it kosher to run my new propane line through the abandoned ductwork (that is literally on the other side of the wall from where the tank will be) or do I have to dig a trench all the way around the house and potentially dig up the water or sewer line running in the same area?

The duct in question will be used as a conduit (no other purpose and could be ripped out, but that would require a lot of crawling through a narrow crawlspace) and ends very close to where the original gas line currently is.

Originally Posted by Steve Scheetz

... or do I have to dig a trench all the way around the house ...

Yes. That is what you have to do if you want the gas line underground.

You could run it into the house and up and over through the attic (which is likely the only accessible area you can get too in the house) to the other side of the house.

Another possibility may be to run is up on the exterior of the house to just below the soffit, then run it around the house to the other side, then in or back down to where you want it to go to.

so the abandoned duct conduit idea is a definite no go is what I am reading here. <sigh> I do appreciate the quick response, thank you!

Ok Jerry,

Devil's advocate here. According to the code regarding gas piping in ducting, it clearly says circulating air duct, ventilating duct, etc... An abandoned duct is no longer a "circulating air duct".

I could use a short length of 4" metal duct as a conduit/sleeve for a gas pipe through the foundation (UPC allows this), so, why can't Steve use a longer abandoned duct as a sleeve/conduit. Is this because the IRC does not allow gas piping through the concrete foundation?

G2415.1 (404.1) Prohibited locations. Piping shall not be installed in or through a circulating air duct, clothes chute, chimney or gas vent, ventilating duct, dumbwaiter or elevator shaft. Piping installed downstream of the point of delivery shall not extend through any townhouse unit other than the unit served by such piping.

I suppose that I should have stated "according to the IRC and codes based on the IRC, subject to amendments".

See attached (using phone, so I took a screen shot of IRC).

What does UPC state regarding the above?

Edit: Hmm ... screenshot not showing. Guess I'll need to address this later on my computer.

Ahhh ... file name of screensjo was too long

Originally Posted by Jerry Peck

I suppose that I should have stated "according to the IRC and codes based on the IRC, subject to amendments".

Hi Jerry,

I figured that you were working from the IRC, so a clarification was not necessary (at least for me).

But, my question is essentially: Is the foundation penetration issue the primary reason he has to trench around the whole house or does it have to do with the abandoned duct? For example, if the abandoned duct was only 6-8 inches long and went through a wood-framed wall, would it still be prohibited? At this point, is is clearly no longer a "circulating air duct", but is now a chase .

It's frustrating for home inspectors that California only uses the building portion of the IRC. Since we are not totally in sync with the rest of the country, these differences can make taking the NHIE difficult as the questions are supposed to be based on the IRC. For the other codes in CA, the model codes are the NEC, UPC, and UMC. Larger buildings are, of course, the IBC. I don't recall which fire code CA uses.

I wonder why the IRC does not allow gas piping to be inserted through the foundation, but the UPC does.

This is from the 2019 CPC (2018 UPC). As yet, I do not have the latest CPC. 1200 addresses gas piping and 1210 addresses underground gas piping.

1210.1.5 Piping through Foundation Wall. Underground piping, where installed through the outer foundation or basement wall of a building shall be encased in a protective sleeve or protected by an approved device or method. The space between the gas piping and the sleeve and between the sleeve and the wall shall be sealed to prevent entry of gas and water. [NFPA 54:7.1.5]

Originally Posted by Gunnar Alquist

But, my question is essentially: Is the foundation penetration issue the primary reason he has to trench around the whole house or does it have to do with the abandoned duct? For example, if the abandoned duct was only 6-8 inches long and went through a wood-framed wall, would it still be prohibited?
.
.
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This is from the 2019 CPC (2018 UPC). As yet, I do not have the latest CPC. 1200 addresses gas piping and 1210 addresses underground gas piping.

1210.1.5 Piping through Foundation Wall. Underground piping, ...

Is the piping above ground or underground?

I went back to revisit the first post in this current part of the discussion.

I read it (apparently incorrectly) as the ducts were "underground", but Steve actually only says "under my house".

If ... IF ... IF the ducts are "underground" under the house, as some were in some places in Florida, then, yes, trench around the house or the other options I mentioned.

If only "under my house" but "aboveground" ... then there may be a chance to run the gas line "under the house", depending on the type of pipe used, and depending on this: was the house flooded?

If so, the house may need to be elevated above flood/storm surge level. And that would change all kinds of things, not just the gas piping.

Originally Posted by Steve Scheetz

Hurricane Ida Took out the air handler that uses all of the ductwork under my house.

Originally Posted by Jerry Peck

Is the piping above ground or underground?

Hi Jerry,

My read of it is that 1200 is gas piping, 1210 is specific to underground gas piping, so 1210.1.5 is specific to underground piping run through a foundation.

Originally Posted by Gunnar Alquist

My read of it is that 1200 is gas piping, 1210 is specific to underground gas piping, so 1210.1.5 is specific to underground piping run through a foundation.

I don't have the CPC, but the IRC (and IPC, which are the section numbers in parentheses after the IRC number) states:

From the 2021 IRC
- G2415.6 (404.6) Underground penetrations prohibited.
- - Gas piping shall not penetrate building foundation walls at any point below grade. Gas piping shall enter and exit a building at a point above grade and the annular space between the pipe and the wall shall be sealed.

The CPC may address 'through foundation walls' separately from 'underground', however, all applicable sections would apply; i.e., if the pipe is underground, then "underground" applies, and if the pipe is through a foundation wall, then "through a foundation wall" applies, and if the pipe is bot underground and through a foundation wall, then both apply.

That said, I first read read that Steve said "underground" when he actually only said "under the house", and being as "under the house" could be either underground or aboveground. That aspect, for Steve's answer, needs to be clarified ... maybe ... because there are so many other things which could now affect the answer (because the damage was from Hurricane Ida).

Sorry for not being clear.

Background:
My house is actually supported by stilts (albeit very low stilts) My old HVAC system was under the house in the crawlspace that was created when a former owner sealed in the sides to keep the weather and critters out.

When Ida came, it killed my hvac system. Currently the propane tanks are located in an area that is lower, and were surrounded by water when the flood came but by moving the tanks to the side by the road, that will help mitigate that issue.

Knowing that the foundation is on stilts, Drilling through the concrete wall won't do anything to the overall structure (The previous pipe is run in a similar way into the crawlspace.)

I have two exterior mini-splits and 3 wall hanging air handlers in the house that is my primary HVAC, my secondary heat is a wood stove that is pretty spectacular, but none of what I have is using that ductwork. It has been abandoned since the flood in 2021.

My idea for using the abandoned duct was because it happens to be on the other side of the concrete wall from where the tank is going to be, it runs most of the length to where the current propane pipe happens to be, and it would make feeding the gas line through the house so much easier!

But if that is not kosher from a code standpoint, I have a quote from a contractor to dig a ditch around the house and go in near where the water and sewer lines go in.


Steve

Originally Posted by Jerry Peck

I don't have the CPC, but the IRC (and IPC, which are the section numbers in parentheses after the IRC number) states:

From the 2021 IRC
- G2415.6 (404.6) Underground penetrations prohibited.
- - Gas piping shall not penetrate building foundation walls at any point below grade. Gas piping shall enter and exit a building at a point above grade and the annular space between the pipe and the wall shall be sealed.

The CPC may address 'through foundation walls' separately from 'underground', however, all applicable sections would apply; i.e., if the pipe is underground, then "underground" applies, and if the pipe is through a foundation wall, then "through a foundation wall" applies, and if the pipe is bot underground and through a foundation wall, then both apply.

That said, I first read read that Steve said "underground" when he actually only said "under the house", and being as "under the house" could be either underground or aboveground. That aspect, for Steve's answer, needs to be clarified ... maybe ... because there are so many other things which could now affect the answer (because the damage was from Hurricane Ida).

Originally Posted by Steve Scheetz

My house is actually supported by stilts (albeit very low stilts) My old HVAC system was under the house in the crawlspace that was created when a former owner sealed in the sides to keep the weather and critters out.

Steve, a couple of questions.

- About how tall are the stilts? How high above the ground below.

- What is your flood elevation (the reason the house is up on stilts), and did the storm surge/flood water get higher than the stilts?

- Are the walls between/around the stilts breakaway type (designed to breakaway instead of take a storm surge hit and transfer that load to the structure)?

I ask because being on stilts indicates that the house is up not only for flood elevation (rising water) protection, but for storm surge and wave action (moving water).

Flood (rising water) only just elevates the finished floor above anticipated depth of flood waters (allowing foundations which are fully enclosed), whereas storm surge and wave action requires that the lowest horizontal structural member be above the wave action, requiring foundations which allow the free flow of water beneath the structure (such as stilts).

Regarding propane tanks. Buried tanks are required to be anchored to resist floatation, and aboveground tanks are required to be anchored to resist floatation, storm surge, and wind.

With your house on stilts, it indicates that the walls should be breakaway walls, so nothing should go through the wall (because the walls would be designed to fall down). Instead, the propane lines, electrical wiring, plumbing piping, etc, would be attached to the stilts and not turn horizontal and cross under the structure - above the required elevation.

Which brings up your HVAC ducts, they should also be above that required elevation and be protected from wind and wave action.

To me, your description indicates involvement of the building official (i.e., the building department under their authority) to advise you on what is allowed and not allowed by code.

They won't "help design" what you need, but should be able to tell you what they could approve ... such as: those walls were not done with a permit (if the walls were permitted in the past, the walls may no longer be allowed - they would know).

So the house is low to the ground When I say on stilts I mean it is not held up by any outside wall.

The old air handler was completely under water during ida, so was most of the ducts. No matter where I put this, it will could potentially be exposed to flood water (Working to raise the house, but when I can get a quote to raise and lower on the new foundation, but I cannot get a foundation guy to come out to even give me an estimate, that idea is somewhat of a dream for me.

Anyway, moving the tank will get it out of the way of any flood waters. I could go through the wall (the wooden part) and still get to the duct work. I could dig under the concrete wall, and take some time digging a trench in the crawlspace, but damn would that suck.

However, the end goal is to then connect it to the existing gas line, in the crawlspace, headed to the water heater and the dryer.

Steve

Originally Posted by Steve Scheetz

So the house is low to the ground When I say on stilts I mean it is not held up by any outside wall.

Okay, let's start there and clarify our starting point.

I'll describe and older construction method used on older homes in Florida and other locations, and some locations may still use that method.

The house is supported on piers, with (hopefully) concrete or masonry footing supporting the piers (usually concrete, but much older homes may have masonry, i.e., brick footings).

The piers may have just enough space to get under the floor joists, beams and girders (I have been under some in Miami/Coconut Grove/Coral Gables which didn't even have enough space to get under much) to some with piers which were 2 to 3 feet tall. Same thing on other locations, including Gainesville and surrounding areas.

The height were, for the most part, high enough that flooding did not reach the bottoms of the wood floor systems. I suspect that those old builders knew the depth of flooding in the area and built slightly above that height. I've been under many older houses in Hollywood and Ft Lauderdale with multiple flood waterlines showing on the inside of block foundation walls and piers.


Does that describe your foundation (temporarily ignoring the concrete block wall around the perimeter)?

Are you sure that the concrete block wall was added later and not part of the original construction?

Close enough. My house started out as a cottage in an area full of cottages. Since it was built in the beginning, all but one of the other cottages (now my neighbor's house) were swept away over the years.

Now, since 1938 when they started recording, the flood waters hit my house 4 times total. All of them close to but not into the beams.

After each of the floods, everyone was given carte blanche to rebuild. My house was added on 4 separate times. One toward the stream, where I am sitting now in the kitchen, one toward the road (the other side of which I want to put the tank), and two more on the side one being on a slab of concrete the other built in piers like the house (screened in porch)

Ah, now we have a good starting point and understanding of what has transpired.

Originally Posted by Steve Scheetz

Close enough. My house started out as a cottage in an area full of cottages. Since it was built in the beginning, all but one of the other cottages (now my neighbor's house) were swept away over the years.

"Swept away" indicates more than just flood/rising water, more like in a floodplain of a river/stream/creek which gets rushing floodwaters, such as the "flash flooding" we've all likely seen on the news lately.

(Bold, italics, and underlining are mind, keep this information in mine)

Now, since 1938 when they started recording, the flood waters hit my house 4 times total. All of them close to but not into the beams.

Similar to what I described with waterlines indicating each flood height. Except that all but two of the cottages were swept away - which shows that those other cottages should not have been built where they were (at least not like they were built, on stilts would be a "maybe", the "maybe" comes from scour of the ground where the pilings - stilts - go into the ground, and from the force flow of the floodwaters and debris trying to knock the pilings over).

After each of the floods, everyone was given carte blanche to rebuild.

That was mistake number 3.

Mistake number 1 was building the cottages in the floodplain. Mistake number 2 was not learning from experience.

Which brings us to the original post on this sequence and current experience.

Keeping in mind what was stated above "All of them close to but not into the beams".

Originally Posted by Steve Scheetz

Hurricane Ida Took out the air handler that uses all of the ductwork under my house.

"Ductwork under" a house which has flooded almost up to the beams?

I will presume that there is no FEMA flood insurance on this house, and that the AHJ (Authority Having Jurisdiction), the local building department, does not have much of a code, or has a code but does not enforce it

Starting from scratch again, let's look at it this way:

You have a house in a floodplain, which is known to have flooded multiple times in the past; including sweeping away entire cottages; which floods almost to the floor beams; has part of the structure on a concrete slab (presuming on an high area of a sloping lot which doesn't get flooded); and had HVAC ducts under the house in the floodwater area.

Possibly, the ducts were swept away during flooding from Hurricane Ida.

Question is essentially:

The propane tank will be relocated from the floodplain behind the house to the higher area in front of the house and the gas line will need to be routed from the front of the house to where the HVAC equipment is at the back of the house.

Am I allowed to run the gas line under the house, or am I required to run the gas line around the house?

If I am allowed to run the gas line under the house, is it okay to run the gas line through one of the old ducts?

Answer is basically:

The ducts should not have been under the house due being in a floodplain. All ducts and such should have been a minimum of 1 foot above the flood elevation (which, in this case, can be established from the highest waterline from the past flooding). All ducts should be removed.

Note: The house is on piers and had a concrete block wall constructed around the perimeter of the house, enclosing the crawlspace under the house. There should be flood vents in the perimeter wall located such that the floodwaters are not allowed to be deeper than 1 foot on the flooded side of the wall to relieve floodwater pressure on the concrete block wall. The flood vents should be located as required/specified by FEMA and flood codes (IRC Section R322 Flood-Resistant Construction covers the issues brought up here, and additional flood issues which should also be considered),

The gas line piping, depending on material used and local codes, is likely allowed to run aboveground, through the foundation wall, and under the house to the location that it is needed.

Put the gas line in the old ductwork? Why? How would you be able to support it and secure it?

If the duct was damaged in and is no longer useable as duct, what would likely happen during another flood and there was an unsupported and unsecured gas line in it?

Provided the local codes allow, and using gas piping material allowed by the local codes, it sounds like the AHJ would allow going through the concrete block wall (it isn't a foundation wall, but would be treated as one for this purpose), attaching the gas piping to the underside of the flooring system above (which has been stated as having been above previous floodwater depths, even though not 1 foot above such floodwaters).

Added with edit: I used the term "floodplain" as the overall term, however, FEMA uses specific terms for specific parts of the floodplain. Such as for the part which swept away the other cottages were likely in the floodway, while your cottage is likely in the flood fringe. I am also adding a drawing I found online of the terms and their relationship to the river/stream/creek shown in the drawing.

Yes to flood insurance (would not have been able to get my mortgage without it). the owners of the other cottages were given a payout by FEMA, but my house, and the one next to it were permitted to remain.

Again, I am interested in raising the house, but until I am able to get a quote to help make that a reality, this was one of my options.

My thought for using the duct was to provide an existing conduit, but I can figure out something else along the support beams. I had originally thought about that semi-flexible line that is black in color, but maybe a pipe would be better?

Originally Posted by Steve Scheetz

I had originally thought about that semi-flexible line that is black in color, but maybe a pipe would be better?

Given that history has proven that your house is subject to floodwaters almost to the beams ... I would greatly reduce the risk of damage to the CSST gas line under the house from floodwaters by going with hard pipe (black iron pipe).

Thank you for your insight. I will work on this advice moving forward.



Steve