Can Kilz Be Used Outside? (Best Alternatives for Outdoor Priming)

Maybe you have a can of unused product lying around and don’t want to waste it. You might as well use it on that outdoor patio of yours, right? Think again!

Unfortunately, not all Kilz primers are designed for outdoor use. Exterior primers often adhere better, block stains more, and last longer than interior ones. Furthermore, exterior Kilz products may contain biocide or other mildew/mold-killing chemicals that can affect the environment.

There are hybrid primers that work on both indoor and outdoor surfaces. The Kilz Original is an example of a hybrid primer. But it’s just a bad idea to use Kilz interior primers outside. Read on to find the best alternatives to Kilz interior primers.

Is Kilz Interior Primer Good for Outdoor Use?

Your home provides that first impression. Houses with peeling and stained fences or walls are often the subject of much talk and gossip in the neighborhood. Perhaps now is the time to finally impress your neighbors with a flawless front porch.

However, not all primers can withstand the rigors of outdoor use. 

Exterior surfaces are more exposed to harsh conditions like excessive sun or wet thunderstorms. Therefore, these surfaces require a primer with UV blocking power and excellent adhesion. Aluminum sidings and vinyl will also need specialty primers suitable to handle the PH level.

How to Tell If Your Kilz Primer Can Be Used Outdoors

garden fence painting

It can be confusing to decipher which primers are suitable for the outdoors and which aren’t. This is especially true if you don’t know whether your primer is a hybrid or not.

Check the primer container for an “Exterior Use” inscription. If it has one, you can use it outdoors. But look out for ingredients like biocides, mildewcides, or other chemicals for killing molds or mildews. Primers with these ingredients should be used indoors only.

Kilz primer that can be used outdoors

Exterior primers will also contain UV inhibitors for exterior surfaces that receive lots of sunlight. 

Keep in mind that some hybrid primers emit noxious odors, which may cause breathing problems when used indoors. 

Can You Use Hybrid Kilz Primer for an Outdoor Paint Job? 

Primers are a crucial part of outdoor painting projects: the material acts as an undercoat to increase the adhesion of paints to the surfaces. 

But primers aren’t intended to provide coats of paint. They’re only primers. And many combination paint-primer products don’t actually contain any primer, meaning you’ll need to buy some separately anyway.

So, avoid the stress of redoing a shoddy job and select Kilz Original, Kilz 2 Multi-Purpose, or Kilz 3 Premium primers. 

Best Kilz Primers for Outdoor Use

Kilz Exterior Primer

For outdoor use, you want to choose a primer that contains UV inhibitors and stain-blocking features for areas that receive more sunlight. 

Kilz Premium: Best Exterior Primer for Heavy Stain Blocking

Kilz Premium is a water-based primer for covering tough tannin bleeds and water stains on wooden surfaces. It also contains a mildewicide to protect against mildew and mold. 

As a plus, Kilz Premium does not contain VOCs. So, you can also use it for interior surfaces without worrying about toxic fumes. 

Kilz Mold & Mildew-Resistant Primer – Best Primer for Killing Mildew 

Is mold covering the walls of your home? Molds and mildews multiply in places with high humidity, temperature, and moisture. To remove and prevent the growth of molds, professional painters often recommend the Kilz Mold & Mildew Resistant Primer. 

This water-based primer contains an EPA-active additive for killing mildew and mold. It also forms a protective coating that prevents water from permeating the primed surface. The primer also blocks odors from pet urine, molds, and cigarette smoke

Lastly, the Kilz 3 Premium is more of an all-around primer. It works as an adhesive, sealant, and stain blocker, which makes it ideal for outdoor use. 

How to Apply Kilz Primers on Exterior Surfaces

painting exterior surfaces 

Once you’ve selected your primer, all you need to do is apply it to an exterior surface. To make sure you get it right the first time, consult the following steps:

Prepare the Surface 

The substrate must be free of oil, grease, chalk, mold, or any other contaminant that can reduce the efficiency of the primer. To prepare the surface for a coat of primer:

  • Use a detergent solution to wash brick, masonry, stucco, or plaster and allow it to dry. The Kilz Original primer works best on masonry surfaces that have dried. 
  • Use a scraper to scrape off peeling exterior paint and sand it down. 
  • Wash mold/mildew-covered surfaces with a mildew remover. 
  • If it’s a glossy surface, use sandpaper to sand it thoroughly before priming.

Apply the Primer

Most exterior primers contain VOCs that produce fumes and odors. So use a face mask and eye covering to prevent health issues and follow these guidelines when applying coats of primer:

  • Depending on the consistency of the primer, use a brush, roller, or spray. Rollers with a 3/8″ to 1/2″ nap are perfect for smooth surfaces, while 1/2″ to 3/4″ naps are suitable for rough surfaces like porous wood.
  • Apply the product when the temperature is within 2°C and 32°, and the humidity is 50 percent. 
  • Prime the entire surface for an even coat. A gallon of Kilz primer will cover 200 to 350 square feet with one coat. Applying just one primer coat is often enough to seal in odors and stains. 
  • To test for stain bleeding after priming, apply the topcoat to a small part of the surfaces. If the stain bleeds through, apply a second coat of primer. 

Note: Clean your tools and any paint splatter with mineral spirits or other solvents. Then, dispose of spirits-soaked rags according to state and local guidance.


Only some Kilz primers are designed for exterior surfaces. Remember to identify the type of Kilz primer you’re grabbing before making a purchase. Feel free to consult the above tips any time when in doubt.