Zinsser Mold Killing Primer Vs KILZ Vs Drylok: Which Is Right For Your Project?

Finding the right waterproofing product is critical to keep out mold and prevent damage. Three popular waterproofing products are Zinsser Mold-Killing Primer, KILZ, and Drylok. We researched these products, and in this post, you'll learn their differences and best uses, so you can decide which one is right for your project.

Zinsser Mold-Killing Primer can be used as a protective coating for non-porous interior and exterior surfaces. You can use KILZ on basement and porous masonry surfaces. Drylok can be applied to interior masonry surfaces. All three products have mold-resisting capabilities.

These products have similarities, but you should choose what is suitable for your home projects. All three products have a proven reputation for fighting mold. Read further to learn more about each product and how to know which to choose.

collaged-photo-of-zinsser-mold-killing-primer-and-kilz-and-drylok-paints, Zinsser Mold Killing Primer Vs Kilz Vs Drylok: Which Is Right For Your Project?

Comparing Zinsser Mold-Killing Primer, KILZ, And Drylok

These three popular products can help combat mold in your home. They are household names in waterproofing and stain-blocking. Find out about each product below so you can decide which to use for your projects.

Zinsser Mold-Killing Primer


Zinsser Mold-Killing primer provides a barrier against a fungi and bacteria. This product claims to kill mold when you paint over it.

It also kills and prevents the growth of mildew, moss, fungi, and odor-causing bacteria. Applying the primer can also solve moisture issues.

You can use the primer for non-porous interior and exterior surfaces (e.g., plastic, metal, glass). It is also suitable for residential, commercial, and industrial applications.

The primer has an EPA-registered antimicrobial ingredient, so you get quality protection.

Applying the product is not difficult, but you should refer to the product manual for preparatory instructions. You need clean the area you are treating for mold, and then apply the product directly to the surface.

The primer should dry within 30 minutes, and you can add a top coat of paint after an hour. If you want optimal protection, wait at least 72 hours before applying a top coat. 

Click here to see this product on Amazon.

Listed below are some pros and cons of Zinsser Mold-Killing Primer.


  • Drying time is faster than KILZ or Drylok
  • Fewer volatile organic compounds (VOCs) as compared to KILZ
  • Covers strong smells and stains on surfaces
  • Helps paint to adhere well to the surface 
  • Kills existing molds and mildew
  • Blocks water stains
  • No sanding required


  • Difficult to spread
  • Has a strong odor
  • Less effective for penetrating surface pores due to thickness
  • It is only a primer, so you need to add a top coat. 

Do not depend on this product if the mold situation at home is extensive. Zinsser primer is effective if you need to target a few moldy spots.



KILZ is a basement and masonry waterproofing paint. You can also use it for both interior and exterior uses, but only on porous surfaces.

It is specially formulated to create a barrier that stops water infiltration. However, you cannot use the product on surfaces with active water leaking.

KILZ offers a mold- and mildew-resistant primer film that is stain-blocking.

Click here to see this product on Amazon.

The product requires proper preparation before application. If you're applying it on new concrete, let it cure for at least 30 days.

If you apply it on a previously painted surface, make sure the surface can be repainted and that it is clean and free of dirt and dust, with no trace of efflorescence.

Applying KILZ requires at least two coats. Drying time after each coat is four hours, and it will fully cure in 7-14 days. Always follow the instructions of the product so it will be effective.

Here are some pros and cons of KILZ:


  • Can be applied on wood, metal, plaster, or drywall
  • Freely apply over existing paint, including oil and latex-based paints
  • Comes in white but is tintable
  • Easy clean-up with soap and water
  • 12 PSI water pressure rating 
  • Low VOCs
  • Can be used as a final coat


  • Cannot apply to floors.
  • May lose its effectiveness when frozen.
  • Emits a foul odor when applied.
  • Cannot use it on surfaces with constant direct water contact.
  • Has a limited and non-transferrable lifetime warranty.

If you want to prevent mold on a floor, you cannot use KILZ. The product blocks stains well on wood surfaces such as cedar, pine, or redwood.



Drylok is a well-known concrete and masonry waterproofer. Like KILZ, it protects surfaces from water infiltration. The product creates a semi-impermeable barrier that keeps water and vapors out.

Due to its ability to fight water penetration, Drylok can prevent the development of mold and mildew. It can kill mold in addition to preventing it. 

Drylock is white with a flat and sandy texture. Before you apply it, clean the area to remove any mold and mildew stains on the surface.

You need to apply two coats, and the drying time should take less than three hours. Note that you can tint Drylok to make it more appealing.

Click here to buy this product on Amazon.

These are the pros and cons of Drylok:


  • 10-year fully transferrable warranty
  • High water resistance 
  • Creates an impenetrable barrier
  • Works well on bare masonry walls and floors 
  • Available in four ready-mixed colors with six different tints


  • Only prevents mold and mildew growth
  • Cannot get rid of moisture
  • Cannot be used on wood

Drylok is a versatile choice if you apply it to basement and masonry surfaces. 

Is A Mold Killing-Product Necessary At Home?


Mold is an enemy of households. Mold breeds in places where there is moisture. It is a health risk for your family. If mold is in your home, you may experience the following:

  • Cough and colds
  • Itchy and red eyes
  • Memory loss
  • Lethargy
  • Respiratory and skin allergic reactions
  • Sneezing
  • Stuffed nose
  • Acute idiopathic hemorrhage

People with allergies and respiratory illnesses like asthma or pneumonia are at higher risk of mold exposure. If you don't eliminate molds, health conditions can complicate. 

Mold-killing products such as Zinsser and waterproofers like KILZ and Drylok can help reduce mold. These products can prevent the growth of mold if applied correctly.

Other than using these products, you can also do the following to fight mold:

  • Control humidity levels (around 30-50% throughout the day)
  • After flooding, make sure your home is clean and dry
  • Do not use carpets in damps areas of your house
  • Fix leaks 
  • Have proper ventilation where there is moisture

How To Remove Mold?

If you have mold at home and did not use any of the products mentioned in the post, you can still get rid of it. You can safely remove mold by doing the following:

  1. Use protective gear to prevent direct contact with mold spores.
  2. Choose a cleaning solution. You can use a chemical-based cleaner or a natural option like hydrogen peroxide or vinegar.
  3.  Spray the solution on the spot and let it penetrate the surface for at least five minutes.
  4. Scrub the area to remove the mold. Some chemical cleaning solutions may not require scrubbing.
  5. Rinse the surface with water and dry it.

If you use a chemical solution, check if it is compatible with the surface. For areas larger than 2 x 2 feet, ask for help from professional cleaners.

How To Prevent Mold Growth Inside Your Home?


Waterproofing and mold-killing products are only a part of a greater process. Those products can help remove or prevent mold growth, but you need to address the main source of water and moisture. 

Here are some additional tips for preventing mold growth:

  • Keep gutters and downspouts clean.
  • Fix and seal any cracks and gaps around the house.
  • Dry wet areas immediately.
  • Monitor humidity at home with a moisture meter. 
  • Allow good air circulation around the house.
  • Reroute the water coming from the outside.

Using the products to prevent mold will help as long as the application is correct. 

In Closing


To get rid of mold in your home, you can choose between Zinsser Mold-Killing Primer, KILZ, or Drylok.

Zinsser effectively kills existing mold and mildew and is a good stain-blocker. You can use KILZ on porous surfaces except for floors. Drylok is a versatile waterproofer for basement and masonry surfaces.

Zinsser can remove mold because it has a fungicidal agent. Both KILZ and Drylok only prevent mold from forming by creating a barrier against moisture and water.

Note that there are limitations to where you can apply these products, especially if the surface has direct contact with water.

All three products are effective, but you should choose the right one for your specific project. 

If you found this article helpful, check out these related posts:

How To Get Rid Of Kilz Smell

How To Remove Mold From Painted Walls?

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