Category Archives: Air quality

Tips for Keeping Your Air Conditioning Drain Line Clog-free

Every summer, thousands of air conditioning drain pans in the southern U.S. overflow due to a preventable clog at the condensate pan drain line. If the air handler is located in an attic, most homeowners will realize that they have an issue once it is too late and water starts dripping through the ceiling. If caught quickly, this can be remedied quite nicely. If the condensate pan has been overflowing for several days, however, wet insulation and mold growth on sheetrock and framing can be the result. An insurance claim and professional clean-up could be needed at this point.

The best approach is to check your drain pans twice a year – once near the beginning of summer cooling season and again in August or September when your systems are working overtime to help keep your home comfortable. Whether you do this yourself or hire an HVAC contractor to check for you, here are a few things to look for:

• the condensate drain pan is located directly underneath the air handler. It may have some dampness in summer as moisture is condensing out of the air and dropping into the pan to be exited outdoors
• a pan full of water is not good and an indication that the condensate drain line is clogged
• the line is most commonly clogged with sludge or pieces of insulation, although the clog can occur at an elbow joint or at the termination point outdoors. We sometimes find the line has become buried in landscaping mulch or dirt that prevents a proper flow

To maintain a free-flowing drain line, remove any standing water or sludge from the pan using a wet/dry vac. Compressed air may be used to blow out the line, or you may use a hose to carefully blow out the line. Most clogs will occur at an elbow joint where the line exits the foundation, so you may need to pull the joint apart and let the clog out. Pouring some hot water down the line a couple of times each year will also help keep the line clean.

We like to see the drain line termination point several inches above the ground and away from the foundation so the condensate flows away from the house.

One last thought – drain pans with standing water can harbor some harmful bacteria, including Legionella. If the pan has water in it, we advise wearing respiratory protection. The danger is in breathing the water droplets, not from skin contact.


Mold in a Crawl Space

This is a slightly revised re-post from our very popular June 2012 blog about mold in crawl spaces.

Summer is almost here, and with the warm temperatures comes more homeowner activity in the yard. A few will even open the door to their crawl space and peak inside. What happens if you find a bunch of mold that seems to be growing on the wooden floor joists under your house?

First, understand that a few different kinds of things that look like mold can also stick to joists. Second, understand that some mold on the wood under your house is normal and to be expected, especially if your crawl space is an ‘open’ design with foundation vents that allow outdoor air into the space. Some mold under the house may be defined as ‘normal fungal ecology’, especially in the southeastern U.S.

If you are reasonably sure that your floor system has mold on it and want to know if something needs to be addressed, you may want to consult with an expert, or be prepared to buy a few measurement tools and learn how to use them. An expert is best defined in this case as someone who can assess the crawl space without bias (i.e., they do not sell sealed crawl systems or perform mold remediation).

The optimal time of year for an expert opinion of a crawl is during summer months. This allows the expert to view the crawl when mold is most active, outdoor humidity levels are up and when the house is using air-conditioning.
Here are the steps your expert should take:

  1. While wearing protective gear, crawl through the entire underside of the house and document conditions with photos of the vapor barrier, foundation walls, floor insulation, joists/sub-floor, and any mechanical equipment (especially air handler & ductwork;
  2. Collect wood moisture measurements of several joists and the sub-floor, especially near plumbing penetrations and near the foundation if moisture is observed;
  3. Check the vapor barrier for tears or gaps that could allow soil moisture to evaporate onto the floor system;
  4. Measure soil moisture content if it appears to be damp. Note if all the soil is damp or just certain areas;
  5. Note any strong musty odor. A crawl space should smell earthy, not musty;
  6. Note any debris such as old pipes, insulation or ductwork lying on the floor. These should be cleaned out;
  7. Warn the homeowner of the danger of storing gasoline-powered yard tools under the house, especially if they are near a gas-fired furnace (we have seen this hazard all too often);
  8. Observe the level of air movement through the crawl space. We often find a ‘dead zone’ near the center of larger crawls, which is usually home to more than the typical amount of fungal growth.

Your expert should be able to provide a report that includes a list of observations & recommendations. Here comes the tricky part – how do you know if the mold in the crawl space is at a normal level and is unlikely to harm the family living in the house?

This is where experience plays a large role. Someone who is new to crawl space inspections may miss something important, make a big deal out of something insignificant, or not know how to communicate their findings very well. Other variables that come into play are the tightness of the duct system under the house, the number of occupants who are sensitized to mold and  claim to be experiencing health effects, and the air quality inside the home. It is important to understand that bacteria or mold in a crawl space will find their way into a house through gaps in the floor system and HVAC components and on thermal air currents that naturally travel upward from the crawl to the attic. An expert should be able to measure the likely impact of mold on your indoor environment or be able to direct you to someone who can.

A final note about the collection of samples from suspect mold in the crawl space. It is not always necessary to know the exact level or species of mold (information lab analysis will provide), however, sample collection is often useful, especially if someone in the home suspects a health issue that could be related. Ask your expert to explain their sampling method and what information they hope to gain by sending a sample into a lab for analysis. An experienced individual will be able to clearly explain why sampling is necessary and how it will guide the process of determining if the crawl space has a normal fungal ecology.

When Do I Need an Indoor Environmental Professional?

Perhaps you’ve had a pipe break or a roof leak, or maybe have noticed something that looks like mold growing on your basement furniture. The next step is often an important one in determining the outcome of your moisture issue. Most of the time, a property owner will contact their insurance carrier, who will typically arrange for an adjustor to visit the property. The adjustor will usually be making a decision as to the validity of a claim to be covered under the property’s insurance policy.

From there, you may be advised to contact a moisture or mold mitigation contractor. This is where the process can become a challenge. First, it is important to know that, as the property owner, you have the right to use the contractor of your choice. You do not have to work with a contractor recommended (or seemingly required) by the adjustor. Second, the contractors may offer up vastly different opinions on what needs to occur and the cost to follow their opinion. If your property claim has been approved by the insurance company, the latter may not seem to matter but my advice is that you consider the quotes as if you were going to be paying for them out of pocket.

What happens if your claim is denied or you don’t involve an insurance company for some reason. You may be tempted to opt for a ‘free’ assessment from a contractor. While this is not a bad idea, keep in mind that the contractor is providing a no-cost assessment with the goal of selling you one of their services, many of which are costly.

This is one of the times when an independent assessment from an Indoor Environmental Professional (IEP) can be very important. I like to explain that an independent assessment will keep the contractor honest….not that they are not honest, but it’s like having a mechanic not associated with the car dealer there to advise you when being told by the dealer that you need a new transmission. While the dealer may be providing good advice, it provides peace of mind to know that you really need to spend thousands of dollars on your vehicle.

An important point to remember is that no fewer than 30% of people who contact our office for a mold assessment end up needing to hire a mold contractor. We have saved property owners a lot of money when there is a simple and inexpensive solution to their issue. While there is no substitute for a quality mold mitigation contractor when one is required, the independent IEP will guide you so that your resources are used in the best way possible.

One last word of advice – be sure your IEP is truly independent with no ties to the contractor(s) they recommend.

Having a water loss or mold problem is enough of a challenge for any property owner. The suggestions above will hopefully help you understand the process of getting your issue resolved in an affordable and safe manner.

Christmas Trees: a Source of Indoor Mold During the Holidays

A study presented at the annual meeting of the American College of Allergy, Asthma & Immunology in 2007 found that indoor mold increased over a two-week period after a live Christmas tree was placed in the room. The study, which was broadcast on CBS and NBC news, found that airborne mold counts increased from a normal count of 800 during the first 3 days to a high count of 5000 spores per cubic meter of air at day 12.

Although the study was of one tree in one home in the northeastern U.S., allergists from across the U.S. chimed in to agree with the study. Many of the allergists were not surprised by the result given the increase in allergies treated during during the thirty days following Christmas.

ESG has been collecting measurements of mold spore counts inside dozens of homes and businesses across North Carolina during the holidays for many years. Our data suggests that the lone study mentioned above is accurate: indeed, airborne mold counts seem to spike around the New Year and continue to be elevated, especially with a very allergenic mold called Myxomycete. Our office gets a number of calls from people who are suffering from allergies during this time, and in one case a young couple was so affected they stayed in motel until we could help figure out how to reduce the airborne mold counts in their home.

Here in North Carolina, the Fraser Fir is considered the finest Christmas tree, and many families enjoy the tradition of going to the mountains in western NC to cut a live Fraser Fir. What can a family do to help prevent a holiday-dampening allergic reaction? Medical professionals say that vigorously shaking a live tree before bringing it in the house will help. Some people use their leaf-blower to vigorously ‘wash’ the tree with air. Do not wet the tree down, as moisture will activate the mold to grow. Once brought indoors, keep the house around 68 degrees and locate the tree away from any air vents that could disperse the mold around the house. Finally, limiting a tree to a one-week stay inside the house should keep fungal counts low enough for most people to tolerate.

We will discuss the pros and cons of artificial trees in another post in a few days.

It’s a Great Time of Year to Fix Leaky Air Ducts


Craig Whittaker headshot smallCraig Whittaker founded Environmental Solutions Group in 2002 to provide impartial evaluation of properties relative to environmental health. He has assessed more than 1500 properties, has written thousands of environmental reports and is frequently asked to speak about building science issues.

If your home has central heating or air conditioning, your air ducts are one of the most important systems in your home. The air ducts are responsible for delivering conditioned air from the air handlers, which for most homes are located in the attic or crawl space. If the ducts are leaking air, you will spend an average of 20% more on heating your home this winter. For our friends north of the Mason-Dixon line, this can add up to hundreds of dollars worth of wasted energy.

Leaky ducts also draw unfiltered & unconditioned air from your attic or crawl space into the house. This can lead to poor indoor air quality from mold and bacteria, increased humidity during summer and cold spots in your home during winter. Even a small leak at a duct connection can cause the room served by the leaky duct to be several degrees colder than neighboring rooms where ducts may not be as leaky.

Leaking ducts also have more serious consequences. They often negatively pressurize a home, causing outside air to force its way in to balance the air pressure. This can cause a fireplace to backdraft, drawing deadly carbon monoxide (CO) down the chimney instead of allowing it to exit up the chimney. If you have natural gas appliances, the backdrafting from negative pressurization can also be dangerous, which is why it’s so important to have a functioning CO detector in your home.

You may be wondering if the ducts in your home are leaking. It’s best to assume that they leak as even newly-sealed ducts are not 100% airtight, and older systems often lose 35% of their heat through leaks.  In North Carolina and many other states, duct tightness testing is mandatory when new residential systems are installed, a vital step towards saving the power companies from having to produce more energy during peak demand.

The Department of Energy recommends having a qualified professional check for leaking ducts, followed by having them sealed and insulated. While gaps in conditioned spaces are relatively easy to repair, gaps at ducts in unconditioned spaces should be professionally sealed to ensure the use of appropriate sealing materials.

ESG’s sister company, ESG Energy, assesses hundreds of duct systems each year and can assist you in identifying leaks, or verify that leaks have been corrected properly.

In review, leaky ducts raise our heating and cooling costs and may lead to unintended health consequences such as allergies and more serious injuries from mold, bacteria and carbon monoxide. Before it gets cold outside is a great time to check your ducts.

Learn more at or visit for tips on sealing air ducts.

The Danger of Carbon Monoxide


North Carolinians have recently been reminded of the inherent danger of carbon monoxide poisoning. In April of this year at a hotel in Boone, NC, a couple visiting from Washington state died from asphyxiation due to carbon monoxide. The hotel was told to fix the leaking gas heater at the pool immediately, but apparently something went wrong. This past weekend, a child died from carbon monoxide poisoning while staying in the same room as the couple that died less than 60 days ago.

While the most common causes of death from carbon monoxide include running a gas or charcoal grill indoors, operating a generator without proper ventilation, or running a car in an enclosed garage, combustion appliances such as gas stoves, fireplaces and hot water heaters can also leak deadly carbon monoxide (CO) into a room. It doesn’t take much CO to kill a person and it can happen fast, usually while that person is resting or falling off to sleep. What’s more, the victim of CO poisoning doesn’t even realize what is happening.

CO is an odorless and colorless gas, therefore, people have no warning other than a short list of symptoms – that is, if they are awake and paying attention! The symptom list includes severe headaches, dizziness, mental confusion, nausea & fainting. The more CO that is present, the more severe the symptoms and the more important it is to immediately get fresh air. Go outside and take deep breaths as opening windows & doors will usually not reduce the level of CO in a room.

Everyone reading this should take carbon monoxide poisoning seriously, and use CO detectors in their home and workplace. These inexpensive devices could save your life. If you use gas appliances at home, check with your local utility provider or fire station about annual check-ups of your appliances. Private firms with expertise in combustion measurement can also provide this service (full disclosure – ESG measures CO levels at every one of the hundreds of air quality assessments it performs each year & we are happy to assist you).

The deaths at the Best Western in Boone were preventable. Please follow the rules of gas combustion safety and don’t be a senseless victim.

Commercial Foreclosures and Environmental Liability

Craig Whittaker headshot small

Craig Whittaker founded Environmental Solutions Group in 2002 to provide impartial evaluation of properties relative to environmental health. He has assessed more than 1500 properties, has written thousands of environmental reports and is frequently asked to speak about building science issues.

As the housing recovery continues to deplete the existing housing stock, the number of residential foreclosures for sale continues to drop steadily. This is indeed good news for realtors and homebuilders alike, however, there still remains a dark cloud over commercial properties foreclosed upon by the bank. Many of these bank-owned properties reportedly come with an environmental liability, namely mold.

As it’s been nearly three years since I have blogged about the challenge of buying a foreclosed property (see ‘Buyer Beware of Foreclosures’ posted in July 2010), I have some new thoughts that focus on commercial properties. I must first give credit to Russ Banham for his recent article in Business Insurance titled “Foreclosed properties may come with environmental liabilities”. Anyone looking at buying foreclosed commercial property should read Mr. Banham’s article as it delves into the many liabilities faced by banks and buyers – especially mid-market firms without the resources of the big banks to overcome a serious issue.

One of the main concerns with bank-owned properties is the bank having some level of control of the use or operation of the property. This creates bank liability not only for that property, but also for third-party liabilities associated with damage or injury to tenants or an adjacent property owner for contamination that may have migrated to their property. As Mr. Banham states, the issue requires superior due diligence.

Neil Glazer, an attorney and toxic torts expert in New York, has seen the ugly side of commercial foreclosures. Mr. Glazer speaks of banks purchasing commercial properties in bulk with plans to renovate and resell them. The problem is that the properties are often contaminated by mold, which means the bank is going to be paying for what can be a costly cleanup prior to sale.

There are a number of risk management maneuvers the bank can try, such as purchasing environmental impairment liability, pollution liability, secured impaired property insurance and lender’s collateral environmental insurance. Insurance can help create some comfort over taking title to a foreclosed commercial property, but it can be expensive and therefore prohibitive to mid-market institutions. The bank can also attempt to protect itself from liability by asking the borrower to name it as an insured on the borrower’s policy, assuming the borrower carries an environmental insurance and is willing to name the bank on the policy.

 According to Debra Hausser, who markets environmental site and specialties products at Zurich North America, there may be times when a bank wants to assume the environmental liabilities of a foreclosed property. It is often in the best interest of the bank to clean up the property to avoid having to sell it at a discount due to environmental contamination.

 Perhaps the most affordable means for a bank to protect itself is to have an environmental assessment of a property prior to listing it for sale. A good report could be shared with prospective buyers, and the bank would also have an opportunity to correct any glaring issues before a buyer discovers them.