Understanding Mold

Molds are species of fungus that play a vital role in decomposing organic matter in nature. As a home or business owner, understanding mold and its effects are very important. Because molds do not require sunlight to grow, they thrive in low light areas by decomposing organic matter such as cellulose and starches.

Molds reproduce through microscopic seeds called spores that are ejected from the main mold structure. Mold spores often lay dormant for years, waiting for the right mix of moisture and temperature to become active.

Mold Spores

Scientists classify spores as viable or non-viable. Viable meaning spores capable of growth. Non-viable meaning dead and unable to reproduce.
It’s important to note that non-viable spores can still emit toxins unless killed by abatement chemicals and completely removed from the building.

A Hidden ThreatType of Mold - Chalreston, WV

People often question if mold actually poses a threat since it is always present in our environment. Extensive research shows that mold becomes dangerous when it’s contained within a building. Poor circulation and moisture allows the concentration of mold to reach dangerous levels that are not possible in outdoor areas.

It’s also vital to understand that 60% of homes that contain dangerous concentrations of mold show no visible sign of mold growth with a cursory inspection. That’s because mold grows in the dark and damp areas of your home – such as a crawlspace, inside walls, underneath carpet or an attic with a leaky roof.

Residents typically smell a mold problem before they see one, because growing mold spores produce an unmistakable musty odor.

A common misconception is that newer buildings are immune to mold contamination. A poorly built new home is just as susceptible to mold growth. In our experience, we’ve seen mold in home six months after their completion.
Usually this is a result of inadequate foundation work, improper storing of building materials, poor ventilation systems and building design flaws.

Types of Mold

While not all are allergenic or toxic, here’s a few common harmful indoor molds:


Mycotoxins are the poisons produced by molds. The EPA states that mycotoxins can be ingested, inhaled or absorbed through the skin – all with harmful results. Here are a few examples of the most harmful mycotoxins produced by indoor molds:
Trichothecene – the most harmful mycotoxin
Aflatoxin – a strong carcinogen
Fumonisin – contaminates grains & foods
Ochratoxin – linked to urinary tract tumors

Causes of Mold

Water Damage
Water damage is typically the most common cause of mold growth. Leaks such as ruptured pipes, overflowing bathtubs, faulty water heaters or poorly sealed windows provide the right conditions for mold.

Typically these leaks cause mold growth underneath carpet, inside walls and along baseboards – in places you wouldn’t be able to see the active growth of mold.

Fire Damage
When a home or office suffers fire damage, it is very likely that mold growth will follow, provided the structure isn’t completely destroyed by the fire.

While it seems counter-intuitive, a large amount of water is used by fire crews to put out the blaze. The water that makes its way into the foundation and inside the walls is typically missed by hasty cleanup crews.

New Construction
A common misconception is that newer homes are immune to the causes of mold growth. A poorly built new home is just as susceptible to mold growth; in our experience, we’ve seen mold in homes six months after their completion.

Usually this is a result of inadequate foundation work, improper storing of building materials, poor ventilation systems and building design flaws.

Heating, Ventilation and Air Conditioning (HVAC)Mold Water Damage - Charleston, WV

Mold growth inside your HVAC system is one of the major causes of mold growth, simply because of how these units operate. HVAC systems produce a continually high rate of air flow, recycling a mixture of indoor and outdoor air to heat or cool the home. If your air ducts are contaminated with mold, you’re susceptible to a higher concentration of airborne mold toxins.

Important Facts Regarding HVACs

• AC units cool your home by pulling humidity and moisture out of the air, the moisture is collected in the unit by the evaporator coil. An improperly maintained evaporator coil will collect dirt and dust, providing a prime opportunity for mold growth.
• Not changing a dirty air filter, or neglecting to install one entirely, will greatly increase the amount of dust and particles coming in contact with the evaporator coil.
• The humidity of a poorly maintained HVAC is the perfect place for mold to grow and reproduce. Unfortunately for you, that mold is right at the heart of the air circulation system for your home.
• Location of your HVAC system is also important. If the surrounding environment is a damp basement or crawlspace, you can guarantee that spores from the surrounding mold colonies will be spread through the air ducts.

The truth about bleach & mold

You’ve probably heard a lot about using bleach as a means to effectively kill and remove mold growth from your home. Whether as a result of major flooding, or minor water damage – bleach shouldn’t be used as a means to kill mold and stop its spread.

Can bleach stop your mold problem?

The short answer is no. Bleach simply is not designed to be an effective commercial mold killer. In reality, using bleach on your walls to clean up mold growth may actually be doing more harm than good.

Designed for “non-porous” use.

When you look at a bottle of bleach, the label states that bleach works best on a hard or non-porous surface. So that’s something like bathroom tile, glass, a bathtub or a kitchen counter-top. On a porous surface like wood or drywall – bleach is not designed to penetrate deep down beyond the surface to clean and disinfect.
The problem is that when bleach is used on an area of mold contamination, it doesn’t actually kill the mold growth or the sub-surface mycelia (root system of the mold colony). The typically recommended bleach mixture only bleaches the existing mold white or clear – just like bleach is designed to do with clothes – but leaves the mold to continue growing.
Check out Clorox’s website when you get a chance, you’ll notice that they don’t list bleach as a treatment for indoor mold growth anywhere on the site.

The Garden Weed Analogy

A very good example to way to explain how bleach is ineffective at mold removal is to compare it to weeds in your garden. If you took a pair of scissors and cut the above ground part of a weed off, it will grow back in a few weeks time. The root system of the weed is still there, it’s going to grow back.
Bleach does the same thing – removes the green or black stain that mold causes, but doesn’t kill the embedded root system of the mold fungi.

Mold needs water to grow

But the issue of porous surfaces isn’t even the biggest problem with using bleach to kill mold on wood or drywall. The active ingredient of bleach is chlorine – the same stuff you put in a pool to clean and disinfect. But do you know what makes up 90% of a bottle of bleach? Water!
And I’m sure you remember that mold requires moisture to grow and spread.
So once you scrub a patch of mold with bleach, the visible mold will be bleached and wiped away, but the root system will remain untouched. Untouched and given a fresh supply of water to expand its roots. Give it a few days, that patch of mold will be back and larger than it was before.

Oregon State University Study

In 2004, OSU released a study regarding the effectiveness of bleach to remove mold growth from wood surfaces. The entire study can be found here.

Feel free to read the entire study (it’s only a few pages long), but we’ll summarize a few important points from this research.

• They measured the effectiveness of water and water/bleach mixtures (from 2.5% to 20% bleach) to remove the visible staining that mold causes on wood.
• They discovered that while washing the boards reduced staining/discoloration by 5 to 15% – there was no significant difference in the effectiveness between all the treatments.
• So from 2.5% bleach, all the way up to 20% bleach – water was just as effective in reducing discoloration as a bleach mixture was.
• Additionally, they concluded that bleach does not eliminate surface microflora on wood. Microflora being the microscopic fungi that grows into large mold patches.
• Finally, the study notes that reducing the moisture level of wood (below 20%) is necessary for proper mold remediation.

Doesn’t it seem a little silly to douse mold with a cleaner that’s 90% water when the goal is to remove the moisture from the surface? We think it is.

But what about the EPA, CDC, etc?

People often say, “if bleach doesn’t kill mold, why do all these government agencies tell us to use it to kill mold?” Which is an excellent question, because for a long time, bleach was the standard recommendation for mold cleanup.
In the last few years, the perception of bleach as a mold killer has changed with some of these agencies. For example, the EPA does not advise using bleach to remove mold – these days they suggest a detergent mixture. The Occupational Safety & Health Admin. (OSHA) clearly states they do not recommend the use of bleach.
The CDC hasn’t completely gotten on board with not recommending bleach for mold cleanup, but their website does clarify that bleach should only be used on hard, non-porous surfaces. So that’s tile, glass, counter-tops, etc. – not wood or drywall.

Bleach just isn’t up to the task

As you can tell, it probably doesn’t make much sense to use a cleaning agent that is almost entirely water to kill a fungus that needs moisture to grow.
For example, when Novos remediates a building with mold contamination, we use a commercial fungicide that was specifically designed to kill mold. And because of that, the cleaner we use is not water-based.
Simply put, a water-based cleaning agent should never be used to tackle mold growth.