Commerical HVAC code question

Is it required by code in Florida to have all joints and seam sealed for the ducts with mastic on a new HVAC system?

Are you enforcing Florida rules and regulations?

I do not think that it is your within your job purview.
If you found a leak, you should report it as that is a deficiency which is within the scope of your inspection.
It is not our responsibility to dictate how something is constructed unless it is deficient (such as leaking). If you are doing an energy audit then you should conform to that particular industry.

There’s always someone who is going to say this is out of the scope of a home inspection.
I am always amazed to get comments like this. I asked a question. If you know the answer then post it.
If not, don’t tell me what my scope is and what I should and should not be reporting. You have no idea why I even asked the question.
I don’t need anyone’s opinion on how I should conduct my business. Thank you.
And I’ve already got the answer, so I don’t need any other info. Thank you.

You are absolutely right Scott. For all anyone knows you might have done a code inspection on this property and needed information and not a lecture.

I find that statement to be ridiculous. How can you inspect on something if you do not know how it is supposed to be constructed / installed.
Just out of curiosity:

would you report duct tape used on AC ducts to seal the lines, if they are not leaking.

Report on the use of ribbed pipe under the sink. They sell the stuff, but you cant use it.

This list could go on and on, but i wont. Your lack of reporting will do nothing but wind you up in court.

Sometimes we should remove our opinions from the equation and just answer or give info [if we have it] as requested,plain and simple!

Well Scott. What was your answer? I would like to know.

I don’t know FL building codes specifically, which is one reason why I did not attempt to answer.

I know the IBC and UBC require duct joints to be sealed with approved materials. As for mastic - specifically - there certainly could be a local requirement.

The type of duct would also be a consideration as to what should be used to seal joints.


According to a reliable source it is not required by code to seal the joints and seams with mastic, but only that they be sealed by using a proper tape and/or mastic. He did quote another code that should be followed, but the name escapes me at this moment.

This is why I generally don’t do Commercial Inspections and phase inspections, but I am helping out a friend so I figured where better to find the answers I need than on this board.

Does the commercial building code for FL mirror the International Building Code?

Of that I am not sure

In the county I live in, both “code tape” and mastic is required. Why, because the local Mechanical inspectors says so. So the answer is…it depends on what the local AHJ says. There is a tendency for people to come here and ask a question but then want to argue with those who try to help and answer. A little more explanation would help those who take the time to answer tech questions. Other times people ask very difficult questions w/o any kind of photos that would help greatly in understanding the problems. If things continue to go the way they have been for months you won’t be able to get anyone to respond to questions. I think some of that is already happening. Lot of the experienced inspectors have quit sharing their experience and information and everyone loses when that happens.

I agree Doug. I figured my question was simple and to the point, and I was just looking for a quick answer.
I know here that residential HVAC inspections require the mastic, but, as I found out, not necessarily the commercial. You’re right, it does all depend on what the county inspector wants that day

Well, here is the specific section from the IMC

603.9 Joints, seams and connections. All longitudal and transverse joints, seams and connections in metallic and nonmetallic ducts shall be constructed as specified in SMACNA HVAC Duct Construction Standards—Metal and Flexible and NAIMA Fibrous Glass Duct Construction Standards. All joints, longitudinal and transverse seams, and connections in ductwork shall be securely fastened and sealed with welds, gaskets, mastics (adhesives), mastic-plus-embedded-fabric systems or tapes. . .

It goes on to list specific UL standards for materials used to seal ducts.

it’s the OR word that nakes the difference, instead of AND

It does indeed make a difference. . .

It’s also important to remember that codes are the minimum standard. The mechanical engineer, responsible for designing the system, may have specified type and method of sealing. He/she is allowed to “require” standards that are higher and more stringent than your local jurisdiction.

It’s important to have access to design plans if you intend to look for code compliance.

  1. You describe the component type.
  2. You describe the location.
  3. You describe the construction material.
  4. You describe significant inadequacies in the component. Leaking because it is not sealed?

I have not seen anywhere where you must identify the duct sealing component materials and determine if it complies with some AHJ code requirement. You are required to report issues where the component does not perform it’s intended purpose. You don’t even have to report if the sealant is asbestos!

2.4. Heating
I. The inspector shall inspect:
A. The heating system and describe the energy source and heating method using normal operating controls.
B. And report as in need of repair electric furnaces which do not operate.
C. And report if inspector deemed the furnace inaccessible.
2.5. Cooling
I. The inspector shall inspect:
A. The central cooling equipment using normal operating controls.

3.2. Exclusions:
I. The inspectors are not required to determine:

H. The compliance with codes or regulations.
O. The existence of asbestos.
L. Offer or perform any trade or professional service other than home inspection.
Q. Inspect on any system or component which is not included in these standards.

I agree. I also told him that even if it’s not required, it’s not a bad idea to insist on it. It’s in his hands now.


In fact what you are saying is we have a check list and run through it without input as professionals to our client.

What ever happened to due diligence?


Simple answer - Yes.
I would also recommend to your Client, that he/she have the HVAC installing contractor return to the jobsite to correct the deficiency. If the Client has a problem getting service, have the Client contact the local municipal inspector, who missed himself.