No matter if you live in a new house or an old house, you’re likely going to run into mold issues at one point or another.

Mold needs three things in order to grow, organic material, oxygen, and water, three things that are readily available in homes.

In this post, we’re going to talk about mold killing primers and mold resistant paints, and do they really work. We’re also going to discuss how to properly clean and paint over existing mold, prevent future mold growth and give you a little info on mold in general.

DIY Mold Painting Project Index

Mold Killing Primers

Compared to years past, today we have paint options that can not only resist the growth of new mold but even kill existing mold on walls and ceilings.

Mold killing primers will kill any existing mold that it comes into contact with. On a porous surface, however, it may not come into contact with all mold.

It also isn’t meant to be a sealer, meaning it seals in the mold stain. So an ideal solution is to also seal the mold stain before painting.

The Best Mold Killing Primer

Zinsser Mold Killing Primer

When it comes to mold killing primers, there aren’t many products on the market that claim to actually kill mold. As far as wide spread availability, there is only one.

Zinsser Mold Killing Primer

Zinsser Mold Killing Primer is the only product on the market that claims it not only prevents future mold growth but actively kills existing mold.

However there are a few notes to consider before slapping it all over active mold.

First, Zinsser does say that their mold killing primer is meant to be applied on smooth surfaces. If the surface is porous, the primer may not reach the mold in the pores and thus not kill it and allow for future growth.

Other products on the market that claim to kill mold are not available at your local hardware store, and thus don’t need to be mentioned here.

You can buy Zinsser Mold Killing Primer here.

Do Mold Killing Primers Really Work

Interior of a large modern bedroom with a fireplace and ceiling fan. Horizontal format.

According to Rust-oleum, the maker of Zinsser, Zinsser Mold Killing Primer does actually kill the mold and prevent future mold growth.

However, I believe some healthy skepticism is in order.

For me, there is no reason in world to not clean the surface with a bleach mixture before painting. This is a known way to kill and clean mold and bleach is super cheap and can be purchased anywhere.

NOTE: Bleach will kill mold that it comes into contact with, however, it will not do a great job on porous surfaces such as drywall which I discuss more here.

In my professional opinion, it most likely works, but why not kill and clean the area with bleach first to make sure? Your health is worth a small extra step!

The Best Mold Resistant Paints

Grey Basement Room With Painted Trim

For mold resistant paints, you have a much larger selection than with mold killing primers!

Most paint brands offer at least one mold resistant paint with antimicrobial properties.

If you look around here at DIY Painting Tips, you may notice that I am quite fond of Behr products. This is because they are high quality, readily available and not only state a great warranty, but my experience with their warranty is better than any other paint brand. So once again, Behr tops my list.

Behr Marquee

Behr Marquee is Behr’s premium interior paint and primer in one. It typically runs about $46 per gallon and boasts one coat coverage, antimicrobial properties and has great hide and stain resistance.

Behr Premium Plus Ultra

Behr Premium Plus Ultra is my personal favorite paint to use when painting interior walls. For me, it provides the best quality with the perfect price point.

This paint is antimicrobial, washable and stain resistant. It typically runs around $35 a gallon.

Other Mold Resistant Paints

Do Mold Resistant Paints Really Work

Mold resistant paint do absolutely work. They are proven effective and the antimicrobial used in them is FDA certified.

It is recommended however not to paint over existing mold as this will just cover the mold and allow it to continue to grow behind the paint.

Mold resistant paint prevents the future growth of mold only on the paint surface itself. They will in no way prevent mold growth in your drywall, framing or on other surfaces in your ceilings and walls.

How To Clean and Paint Over Existing Mold on Your Walls and Ceilings

Cleaning Mold on Walls - Mold resistant paint

I’m not going to be addressing mold found in framing, attics or other areas in this post. That is for a different website.

What we’re focusing on in this post is mold on your walls and ceilings that needs to be addressed through painting and drywall.

If you’ve found mold on your walls (or ceilings) and it’s more than just surface mold when you find it, such as it goes into and behind the wall, then removing the drywall and replacing all affected areas is the best solution. You do not want to mask large mold issues with paint!

IMPORTANT NOTE: Bleach WILL NOT kill mold that is beyond the surface on the drywall. Mold loves porous surfaces like drywall. The problem with bleach is that it cannot penetrate all the pores in the drywall and kill all the mold. This is why mold will often return quickly to these areas.

If you have a significant mold issues on your walls or ceilings, you will always be better off cutting out and replacing the drywall in those areas.

If the mold is purely on the surface however, there are some simple ways to address the mold.

Step 1: Protect Yourself and Your Home

Paint Respirator

The first step when dealing with mold is to make sure you are wearing the proper safety gear, most importantly a respirator so you do not breath in any spores or mycotoxins.

You should also seal off the area to prevent mold spores from going into other areas of your home. A HEPA vacuum and HEPA furnace filter will help clean the air as well.

Step 2: Kill and Clean The Mold

The first step is to kill the mold and clean the surface.

This is most commonly done by washing the area with bleach and water mixture.

Mix 3 parts water to 1 part bleach. The bleach mixture will kill the surface mold and help remove the stain color from your walls.

Make sure to wear a respirator and rubber gloves when using bleach as the fumes are toxic and bad for your skin.

Rinse the area with a wet rag to remove the bleach and allow the area to dry 100%. A fan and/or dehumidifier will help significantly.

Step 3: Prime The Area With Mold Killing Primer

Next prime the area with Zinsser Mold Killing Primer. Zinsser Mold Killing Primer has an EPA registered antimicrobial added into the paint that kills and prevents future mold growth.

Zinsser Mold Killing Primer is actually a perfect product to prime an entire bathroom with before you have any mold issues to help prevent the growth of mold on any of your walls in the future.

Occasionally you may find that Zinsser’s Mold Killing Primer may not seal the stain left behind by the mold. Don’t worry, this does not mean that it’s antimicrobial properties are not working. An additional sealer may be required such as Kilz Oil Primer (found in an easy to use spray can).

Step 4: Paint The Area With Mold Resistant Paint

Once your mold killing primer is dry, you’ll want to paint over the area with a mold resistant paint.

If you use regular paint over your primer, you are actually giving new mold a surface to consume and start new growth on.

Mold resistant paints work much like mold killing primers in that an antimicrobial is added to the paint that helps prevent future mold growth on your walls and ceilings.

Safety For Working With Mold

If you have found mold in your home and you plan on remedying the issue yourself, you need to make sure to take the appropriate precautions.

Make sure to wear gloves, a protective suit, a respirator and use a HEPA filter vacuum to make sure mold spores don’t escape into your home.

Disturbing mold without a plan for protecting yourself and keeping the spores contained can cause health problems and even help the spread of new mold.

How To Prevent Future Growth of Mold On Your Walls

Mold Resistant Paint - Moldy corner walls

While priming your walls with mold killing primer and painting them with mold resistant paint will definitely help prevent future mold growth, there are other more important steps homeowners should be taking to prevent future mold growth in their homes.

The easiest and most effective way to prevent future mold growth is to eliminate it’s main ingredient, moisture.

By controlling the moisture in your home, you should be able to control any future mold growth as well.

This is done in a few different ways:

  • Make sure to run bathroom fans during showers and baths.
  • Run your AC unit to control humidity in your home.
  • Use a dehumidifier in high humidity rooms and basements.
  • Use a HEPA filter in your furnace to prevent the spreading of mold spores (which cause new growth).
  • Wipe down damp surfaces (showers and floors) whenever possible.

The EPA recommends keeping your home’s humidity between 30%-50% to best control mold growth.

What Is Mold?

Mold on Ceiling

Mold is an organic fungus that shows itself with a fuzzy discolored appearance.

The fuzzy dry appearance of mold is due to the growth of mold spores. Spores are tiny structures produced by mold for the purpose of reproduction.

Mold spores are actually found all around us at all times in the air. The quantities though are typically in a safe amount and present no harm to humans in these low amounts.

Mold spores become a problem when they are found in large quantities in our environments or when certain types of molds are found that produce toxins. This typically happens when you have significant mold growth in your home.

How Does Mold Grow?

Mold needs three things to grow and reproduce in your home.

First it needs oxygen, which there isn’t much we can do about.

Second, it needs organic matter to feed off of such as wood, paint, fabric, foods and other materials.

Last, mold needs moisture. Moisture is the key to mold growth in your home. We cannot cut out oxygen or organic materials in our homes, but we can control the moisture found in our homes.

Is Mold Harmful To Humans?

Testing Moisture Levels - Getting ready for mold killing primer

Most molds do not create significant health issues for humans other than their mold spores.

In low quantities, mold spores are completely harmless and common in our everyday lives. The problem with mold spores is when they are found in large quantities.

Excessive mold spores can cause allergic reactions and respiratory problems in many people that include itchy watery eyes, sore throat, coughing and sneezing.

Some molds however are especially harmful to humans because they produce mycotoxins.

Exposure to high levels of mycotoxins can cause neurological issues and even death in some instances. The biggest harm to humans is prolonged exposure to these toxins when harmful mold is present in your home.

Mycotoxins are not found in all molds and the types of molds that produce mycotoxins are not identifiable through visual tests.

For these reasons, any mold in your home should be considered a problem and dealt with immediately.

Most Common Places Mold Is Found In The Home

Since moisture is a required ingredient in the growth of mold, high moisture areas in your home are the most susceptible to mold growth.

These areas include bathrooms, kitchens, laundry rooms, humid basements, cabinets under sinks, plumbing areas and storage rooms among other places.

These are the areas that you should always keep an eye on for mold growth. The sooner you catch it, the easier it is to deal with.

One area I’ve personally dealt with mold is in the basement of my home when I first moved in. Non-green treated wood was used for the sole plates and drywall came into contact with the concrete floor. This allowed moisture to form on the organic materials in my basement and cause significant mold growth on the framing and drywall. I had to gut and redo my entire basement.

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