Attorney James E. Scott IV (left) fields mold liability questions from South Carolina contractors.
CONWAY, SC — Say you open up a customer’s duct plenum and find mold, or something that looks like mold. Do you make the customer sign a statement that their house has mold, and that you, the HVAC contractor, told them? How do you introduce this? How do you tell your service techs to handle this type of situation?

Or, do you tell the customer they may have a moisture problem, sidestepping the mold question for the time being? Does this leave you liable for mold litigation?

These were the questions facing contractors who attended “Managing Your Mold Liability,” a one-day conference organized by Jim Herritage, educational director of the South Carolina Association of Heating and Air Conditioning Contractors (SCAHACC), the same group that held the Mock Mold Trial earlier this year. (See The News, “Ladies And Gentlemen of the Jury,” March 4, 2002, page 1, and “Mold Trial Has Surprising Outcome,” March 25, page 1.)

The intent of the conference was not to set up the question of whether contractors should or should not tell their customers about mold. However, that’s where it wound up. The speakers (two attorneys and one HVAC engineer) offered decidedly different points of view.

In a nutshell, the attorneys recommended that contractors use legal contract verbiage and job documentation to protect themselves against potential mold litigation. The engineer recommended that contractors should not tell customers they have mold, since the contractors do not have the expertise to identify mold at a glance. They do have the ability to identify HVAC design, installation, and service problems that could lead to excess moisture conditions.


James E. Scott IV, Esq., with Young, Clement, Rivers & Tisdale, L.L.P., Charleston, SC, spoke on “Legal Verbiage to Protect You From Liability.” He advised that HVAC contractors “be proactive like you know it [a lawsuit] is going to come. Then you’ll probably be OK.”

The first thing he advised is that contractors work with their own attorneys to create disclaimers specific to their own companies.

Hold harmless agreements and indemnification clauses, he explained, are “exactly what they sound like: The customer agrees to hold you harmless for mold problems.” They must be drafted using proper language, and if you want something specific, like limited liability for negligent work, it must be stated explicitly.

Such specific limitation re-quests, he pointed out, can be powerful deterrents. “They’re one more hurdle for [the prosecution] to get around.” However, “If they are drafted too broadly or written incorrectly, they can be thrown out entirely. Done well, it’s better to have it than not.”

If your work is being done for a general contractor, it can be more complicated. “If you have to sign their contract, be aware of what you sign,” said Scott. Chances are, the general contractor has a limited liability statement that could throw the blame onto your company.

Consider whether you are installing the HVAC unit prior to the general contractor finishing work on the house. “What about damages that occur as a result of the builder’s crew running the unit and clogging it with debris?” asked Scott. “Consider a clause whereby the general contractor agrees to indemnify you and/or agrees to hold you harmless while the home is still under construction.”

Here’s something that could relate to existing homes as well as new construction. Consider a clause stating the customer agrees that you, the HVAC contractor, will follow all manufacturer recommendations and procedures when installing the equipment. This could include running a load calculation.

While you’ve got your lawyer handy, take a look at your service agreements with an eye towards protecting your company against mold claims. For example, make sure it includes the scope of the agreement, listing not only what you do but also what you don’t do. You may want to include a bold print cause: “We’re not mold inspectors,” only in legalese language, said Scott.

If you do not inspect for mold, state that in your agreement, he added.

Contractor Kevin O'Neill, Jim Herritage, and Craig DeWitt (left to right) discuss details of DeWitt's HVAC presentation.


“Certainly, if you find mold, go to the homeowners,” he said. “You notify them immediately.” You also advise them to seek professional help, document the conversation (“with a signature is best”), and at the very least, “Draft something in your own writing that shows you notified them.” If they won’t sign it, contractors have the option of walking away.

This is where a lot of contractors in the audience raised their eyebrows, and soon afterwards their hands. In a nutshell, if you’re stating that your company’s employees are not mold inspectors, why should you go on the record stating that your customer has mold? Isn’t mold growing nearly everywhere in South Carolina (and similar climates)? If you give your employees instructions to walk away from jobs that have mold, how can you stay in business?

Craig DeWitt, Ph.D., P.E., is with RLC Engineering, LLC, Clemson, SC. He flat-out believes that HVAC contractors should address system problems such as moisture, not mold problems — especially if these contractors claim they are not mold experts. He showed a slide of foam rubber with a layer of something in it; it could have been dirt or mold, or both. Without lab confirmation, he said, HVAC contractors should not be making mold diagnoses.

“Mold is a symptom of a moisture problem,” he continued. “Moisture is the territory of the HVAC contractor.”

Contractors may encounter three types of mold on the job: fungi, molds/mildews, and rot, which is actually a decay fungi. All of these need spores, food, water, and oxygen to survive and thrive. Water is the one element chiefly controlled by the air conditioning system.

Molds, DeWitt said, usually grow on a surface; they need an RH above 80% at the surface (not in the middle of the room); it may affect health, but it’s not much of a structural concern. Decay fungi needs “liquid water,” DeWitt said. This is what consumes wood cell material. It does affect building strength. “Dry rot” is a misnomer, he added.

He then went into detail about moisture dynamics, including the behavior of “heat, air, and moisture, in real life”; psychrometrics (temperature, absolute humidity, relative humidity, and dewpoint); and moisture and air dynamics of wood. Observing wood reactions throughout a home may help an HVAC contractor determine whether a moisture problem has been caused by HVAC condensation or by another source.

For example, mold in a closet could indicate that it’s too cold in that closet. Solutions include increased lighting in the closet, adding a supply duct in the closet, and/or slotted closet doors that increase air circulation. Condensation on windows could indicate a need for insulation or, possibly, heating system back drafting. Gapping of hardwood floors could indicate a need for a humidifier — although many homes in South Carolina and throughout the Southeast typically should not need one. Buckling and warping of wood indicates excess moisture.

DeWitt also threw this out to his South Carolina audience: “Any time you put air conditioning ductwork into a crawlspace, you’ve got an oversized system. It can’t handle the latent load.”


Compared to decades ago, there have been many changes to homes and their occupants. These changes include building materials and methods; heating, cooling, cooking, cleaning, and washing methods, including the addition of appliances; and changes to the way we live, including frequency of bathing and washing and the amount of time spent indoors, in a closed environment, DeWitt pointed out.

Mold needs moisture. Moisture can result from warm air on cold surfaces. Moisture and temperature are related. HVAC systems affect temperature and moisture. Ventilation systems move air around (transport mechanism). Openings and pathways for this air can be planned (grilles, ductwork) or unplanned (cracks, penetrations, interwall and interfloor cavities). Sometimes the unplanned pathways can have benefits, but those do not outweigh the potential problems, DeWitt said.

To control moisture movement, DeWitt said to make your pathway, the ventilation system, airtight; “Put your own known, controllable holes in it;” and provide a complete air path, “from the system to the conditioned space and back to the system.” Remember, “You’re being paid to be in charge of that air.”

To control temperatures, “Don’t cool a surface below dewpoint” unless it is supposed to be (coils, ducts, etc.), or unless you are paid to (from a thermostat setting). However, if the temperatures “can’t get there because of a Manual J problem” — that is, Manual J was not used, or was misapplied — and a moisture problem results, “then it’s your problem.”


This all leads to the topic of whether a homeowner’s moisture problem resulted from the HVAC system (your problem) or building conditions/changes (not your problem).

According to DeWitt, excess moisture probably is your problem if:

  • Equipment cannot handle latent loads.

  • There’s insufficient airflow due to an insufficient return path.

    It’s probably not your problem if:

  • There’s excessive building envelope air leakage.

    In the cooling season, temperature control probably is your problem if:

  • Supply air cools something in the house below the indoor air dewpoint.

    It’s probably not your problem if:

  • The thermostat setting cools something in the house below the outdoor dewpoint.

    In the heating season, excess moisture probably is not your problem if:

  • Mold is anywhere in the house. “These are insulation and envelope problems,” said DeWitt.

    However, it probably is your problem if:

  • Moisture results from HVAC-caused back drafting.

  • You forgot to put a supply in a closet.

    No matter where you live, always follow the building codes, even if they were not specified in your contract. “There is no legal defense of, ‘They didn’t ask me to do it,’” DeWitt pointed out.


    DeWitt wrapped up his presentation with the following summary, to help prevent HVAC-related problems:

  • Own your holes (electrical, plumbing, venting, ducts). “If you make them, use them, close them, or seal what’s left over.”

  • Control your air. “Don’t blow cold or warm air directly on a surface. Give it a complete path. And make it a planned flow, not unplanned flow.”

  • Control your pressures. “Create balanced pressures, nothing greater than 3 Pascals. Do not cause back drafting.”

  • Control your water. “Drain condensate correctly. Install secondary/auxiliary condensate systems. And insulate potential condensation sites.”

  • Follow code requirements.

  • Follow the manufacturer’s specifications.

  • Document it. “Documentation can make you money,” DeWitt said. “Lack of documentation can cost you money.” On this point, he and the lawyers surely agreed.

    Sidebar: Yes or No? Vote At Our Website

    If you, an HVAC contractor, think you have found mold during a service call, should you tell your customers and make them sign a statement that you told them? Look for the Survey located in the left-hand column on The News home page, “Mold: Tell or Don’t Tell,” and cast your vote. We will allow space for your comments, and let you know the results in a future issue.

    Publication date: 11/11/2002