Awesome Ways To Prevent Mold Growth

By: Licensed Mold Assessor Brad Fishbein

March 4, 2023

What if I told you that you can make your home absolutely, positively, completely mold resistant?

Well, bad news for you:

I can’t make that promise to you.

I mean, how can I possibly do that with knowing your living habits?

But here’s what I can do for you:

Below you will be provided with 7 insanely awesome ways to prevent mold growth.

And if you can follow the plan laid out for you below, you can ensure that you will reduce the chances of mold growing in your home greatly!

Consistently Run The Air Conditioning System

Depending upon where in the world you live and what time of year it is, you may prefer to leave the windows open opposed to running the air conditioning system.

That may not be the best idea.


I’m not saying that you cant open the windows on a cool night. It’s amazing when you catch a nice breeze.

As a matter of fact, let me clarify that this does not actually apply to everywhere in the world.

I went to visit one a family member in California and was completely blown away when he did not even have an air conditioning system in the home.

Not central air conditioning, not a split system,


But it made sense, they got a breeze right off of the ocean and there was absolutely no humidity in the air. His home was cool at all times.

So if you are not in a hot humid area or a hot humid time of the year, this actually does not apply to you and you can skip down.

If it does apply to you, this is crucial and you MUST read.

Bottom line:

Don’t keep the windows open all day every day if it is the middle of summer or you live in a hot and wet environment such as the Southeast or the Caribbean.

Why Running Your Air Conditioning Is So Important

I’m going to ask you a stupid question…

…What is the purpose of an air conditioning system?


It’s not a trick question.

If you said the purpose is to cool the air, you are not wrong.

Air conditioning systems do just that, condition the air. But it is not just referring the cooling…

Another very important purpose of an air conditioning system is to dehumidify and pull moisture out of the air.

You see:

Mold needs three components to grow.

Those three are:

  • Water
  • Humidity
  • Something organic to grow on (food, drywall, clothes, etc)

how mold can grow

The one of those three that is often misunderstood is humidity.

Most people think that humidity means hot as far as temperature…

…That is just simply not true.

It can be 70 degrees is your home but if the relative humidity is above 60% than mold will not only grow but actually grow quicker.

One has nothing to do with the other. If your air conditioning unit is not de-humidifying the property than the HVAC unit is not doing its job correctly and you need to have a licensed professional come repair your unit.

Dry Your Home Immediately After You Have A Leak

Mold can start growing in as little as 24-48 hours after a leak takes place. The most important thing to do is dry the water damaged building materials out as quickly as possible.

I’m not questioning your intelligence…

I understand that if you had a leak you are smart enough to try and dry the area as quick as you possibly can.

I mean:

I don’t expect you to play water polo or remote control boats in your flooded living room.

flooded living room

The problem is:

Most people don’t know how to properly dry building materials after a leak.

Your gut instinct is telling you to go in your garage and get that little fan that’s been sitting in there from 1998. But it’s not going to cut it…

It’s not your fault though. This is not something that is taught in school!

That is why there is a whole industry dedicated to this called the water damage restoration industry.

So here’s where it get’s tricky:

Having a water damage restoration company come into your home is not cheap!

Yes, these guys are expensive, but the good news is that your homeowner’s insurance policy will usually pay for it! You may be thinking,

But won’t my insurance go up if I make a water damage insurance claim?

The answer is no not necessarily. Homeowner’s insurance is not like car insurance and it may not go up just by making a claim. Also, the amount it goes up if if at all , will not equal the amount of your insurance claim. You have insurance for a reason, don’t be scared to use it!

DIY Water Damage Drying

Ok, I got to throw a disclaimer out there that if you can make an insurance claim, you should most definitely do that!


You may be absolutely stubborn and not take that advice.

I get it, you are a Mr./Mrs. do it all!

So since you aren’t going to listen to me anyway, I will give you two tips to successfully dry out water damage.

Tip #1

Get a hold of a commercial dehumidifier unit. They are quite expensive to buy, but you can rent these at tool rental stores as well as places like The Home Depot or Lowe’s. You need to make sure that it drains into a tub or sink. You may need to put some small holes in some of the wall covering to properly pull the moisture out of the wall cavities.


***IMPORTANT- You do not want to run dehumidifiers for too long because it will dry everything out. It can cause some tiles to start cracking and crown molding to start pulling from the wall.

Tip #2

Get air movers AKA big freaking fans! You want to set them up on the affected area which will also help dry it out.

Either way, the most important thing is to dry wet areas immediately. The longer you wait, the more likely that will mold will start to grow in your home.

Make Sure Water Is Directed Away From The Home

Any building contractor or competent home inspector will tell that the most important aspect of your home is directing water away from the foundation.

This is even more important if you have a basement.

Water near the foundation can lead to water infiltration and pose serious problems including but not limited to mold.

Here’s how it works:

When water pools up it can find it’s way through little cracks that maybe where the paint and sealant are deteriorated. There is also something called capillary action.

I know, you are probably wondering, “what the heck is capillary action”. Here’s how it’s defined by the U.S Geological Survey:

Capillary action occurs because water is sticky, thanks to the forces of cohesion (water molecules like to stay close together) and adhesion (water molecules are attracted and stick to other substances). Adhesion of water to the walls of a vessel will cause an upward force on the liquid at the edges and result in a meniscus which turns upward. The surface tension acts to hold the surface intact. Capillary action occurs when the adhesion to the walls is stronger than the cohesive forces between the liquid molecules. The height to which capillary action will take water in a uniform circular tube is limited by surface tension and, of course, gravity.

Basically, in plain English it means that water can find it’s way through narrow spaces in the concrete without the force of gravity. So if something like a sprinkler head is hitting the house for an extended period of time, water can find it’s way into the house.

So what exactly does it mean to have water pooling up around your house?


This usually happens on the sides of your home where the ground actually slopes towards the house rather than away. Depending upon the piece of land that your house is on the slope may totally go towards your home naturally.

So you’re screwed, right?

Nope! There are a few things you can do to direct the water away from your home, here’s what you can do:

Build A French Drain System

french drain

Building a french drain system is one of the most common ways you can push water away from the house.

If you don’t know what a French Drain is, it involves digging a trench on the exterior sides of your home.


There are a few different ways in which the French Drain can be built. Sometimes it will be right beside the footing, other times it will be on top of the footing. This is something that your contractor will determine.

Once you dig the trench, you have to lay a pipe down and then fill it back up.

It can be more involved than that and it is not too very hard to do, but it is something better left to a professional.

Install A Gutter System


Gutters are pretty common in areas where tons of rain is expected. Newer construction homes are often built with gutters in place but sometimes it is considered an upgrade on newer homes and people decide that getting those fancy baseboards is more important!

Gutters are a great investment because they will collect water then send it towards the downspout and away from the home.

Have Your Air Conditioning System Including Ductwork Cleaned

Since you are obviously going to follow Number 1 and keep your Air Conditioning running consistently, chances are that there is more of a chance that it will get dirty.

Which in turn means…

….It will need to be cleaned more often.

Let me elaborate:

I’m not saying that it needs to be cleaned every month. Actually, you may not even need to clean it every year, but eventually, your air conditioning system will get dirty.

There are two main components of the air conditioning system that you are going to have to clean. The air handler coils and ductwork.

The Air Handler Coils

The coils are made of metal and metal does not easily support mold growth.

So that means that you don’t have to worry about mold growing on the coils right?


What happens is, dirt, dust, and debris can building up on the coils and mold will start growing on those. It can look like this:

mold on air conditioning coils

Sorry, I didn’t mean to scare you! But it’s nasty, right?

In order to keep your coils clean, it is recommended that you change your air filter regularly. Some of them last up to 90 days, but most need to be changed every 30-60 days.

If you are noticing that the coils are getting dirty, you can spray coil cleaner on them that can be bought at your local hardware store.

If they are excessively dirty, it is recommended that you have a licensed air conditioning professional take the coils out and acid wash them. This should only really have to be done once or twice within the lifetime of the coils if at all.

The Ductwork

So good news and bad news:

Good news: Mold usually won’t grow inside of your air conditioning ductwork.

Bad news: Just like the coils, mold can grow on the dust, dirt, and debris that form over a period of time.

mold in ducts

Duct cleaning kind of gets a bad rap but it is often necessary.

If you have mold inside of your ducts and that’s where the air flows through that you will eventually breathe, it makes sense to ensure mold isn’t growing on them right?

Duct cleaning also doesn’t need to be done often. It should only be done as needed.

Depending upon what material your ducts are made of, you may not be able to clean them extensively and can only treat them with an anti-microbial solution to retard any mold growth.

Don’t Run The Air Conditioning With The Windows Open

ac running with windows open

You may be thinking:

Well, Duh!

But I am making no assumptions. You would be surprised how many homes I have been to over the years where people run the air conditioning system with the windows open.

So if you are one of those people you are not alone.

As you can tell one of the common components that I keep going back to is the Air conditioning system.

It’s just such a crucial part of both starting and preventing mold growth that it must be emphasized!

So why can running the air conditioning with the windows open cause mold?

It goes back to the mixture of cold and hot/humid air.

This can create condensation and start causing mold to grow on your clothes, your furniture, and just about on anything else in your home.

It’s one or the other, but not both! And just remember, it should not always be the windows open when it is humid outside.

Another added benefit of not running the air conditioner when you decide to open the windows on a cool night is that you will save money by not running the AC!

Do Not Paint Over Wall Paper

I get it…

… It’s a pain in the neck to take wallpaper off!

You can just take a nice shortcut by painting right over the wallpaper. Nobody will ever know that it was wallpaper in the first place right?

For a while, yes, you will be able to keep this a secret.

Until one day, a few years down the line you start to get a mold odor in the room where you painted!

Yes, that can and has happened many times before.

Quick story:

I had a client that just bought a beautiful new home, but she couldn’t figure out why there was a potent odor coming from one of her upstairs bedrooms.

We showed up the house and were detecting moisture all along the walls in the bedroom. All other possibilities were exhausted, whether it be due to a leak from up above, the air conditioning system, etc.

Then I finally noticed in the closet behind a built-in shelf there was a seam. It was the wallpaper!

It was such a good paint job I must say! But once we started peeling back all of the wallpaper, this is what was found:

mold behind wall paper

Long story short, $15,000 later, she finally got the odor out of her room. And no, insurance did not cover it!

Why Mold Grows Behind Wallpaper When Painted Over

What happens is the addition of paint allows moisture to get trapped behind the wallpaper.

Because the walls are not “breathing” at all, it is hot and humid behind the wallpaper. Over time the build-up of moisture will allow mold to start growing.

If at any point in time the air conditioning system is not running and this location is over 60% humidity this can cause mold to really start growing very quickly!

Totally avoid having this problem and if you see wallpaper, drop the paintbrush!

Number 7

Install Louver Doors

Think about closed areas in your home…

Like maybe a closet.

What don’t you have there?

An air conditioning vent!

This is especially true in older homes. Keeping the door closed for an extended period of time with no air conditioning will lead to hot and humid air.

Not only will it likely have an odor in the closet due to no air exchange, if you have any kind of leak in the area, mold will start growing lightening quick!

Surface mold can start to grow on your clothes and the walls as well.

So how can you combat this?

By installing louver doors!

louver door

Louver doors have horizontal slats that will allow air to go in and out of closed spaces.

They can be used on HVAC closets, linen closets, and even bathroom doors.

If you do not want to install louver doors than at the very least, you should make a habit of trying to keep the doors open throughout the home as much as possible!

Do You Have Any Tips?

There are much more than 7 ways to prevent mold, do you have any?

We want to hear from you! Leave a comment!

Meet the author: Brad Fishbein is an ACAC council-certified Microbial Investigator. In the fall of 2012, he became a Licensed Mold Assessor in the State of Florida through the Department of Business & Professional Regulation. Brad has helped homeowners with over 5,000 successfully completed Mold Inspections since 2009.

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