Why Is the Paint Bubbling on My Wall?

Whether you’re in the middle of a paint job, or it’s a wall that’s been painted for years, seeing bubbles in your wall paint is always frustrating. So what causes paint to bubble on a wall?

Paint bubbling on your wall can be caused by inadequate wall preparation before painting, heat, or moisture. This bubbling effect – also known as “blistering” – may be a combination of these factors. The appropriate solution depends on the cause of the blistering. 

In this article, we will discuss potential reasons for your wall paint to blister, how to tell what’s causing it, and what to do about it.

Causes of Paint Bubbling

Blistering of your wall paint occurs when the top coat of paint separates from the surface behind it. 

It can be tough to identify the root problem of the blistering you see on your wall.

Sometimes you see one bubble or a small patch of bubbles. Other times, you can see an entire wall of paint covered in bubbles.

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There are three primary reasons you may see your wall paint blistering:

  • Improper conditions for paint application
  • Heat
  • Moisture

How Inadequate Wall Preparation Can Lead To Paint Blistering

We all know that getting ready to paint is not only tedious but usually takes longer than the painting itself.

Despite being a time suck, doing prep work can save your wall paint in the long run. 

One reason that your paint may be bubbling is that you didn’t adequately clean the wall. Grease, dirt, or dust can all create a barrier that prevents the paint from sticking to the wall surface.

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Rooms like kitchens often pose a challenge, as simple things like not effectively cleaning splatters of cooking grease can lead to blistering. 

It’s essential to remove the dust and dirt with a rag and clean your walls before you start your painting project.

Additionally, don’t forget to let your walls fully dry before you start painting.

The next step to avoid bubbling, one that often gets missed, is primer.

While not always required, especially if you’re painting a darker color over a lighter one, primer is a beneficial tool when painting.

The intention of using a primer is to create the ideal surface for your paint to adhere to.

It catches many small spots that your color may have had a hard time sticking to if it hadn’t been used, such as areas with unsanded spackling or stains. 

It’s also necessary when painting latex paint over oil-based paint or alkyd paint. 

You risk seeing bubbling or simply not having your paint stick if you paint latex paint directly over these types of paint.

If you don’t want to use primer on your entire wall, make sure to at the very least prime areas where you see stains, you’ve applied joint filler, fresh caulk, etc., and where there’s potential for your paint to have a hard time sticking.

How Heat Can Lead To Paint Blistering

If you’re confident that you adequately prepped your walls before beginning the painting process, consider heat as a possible source for the blistering.

Paint can react adversely to heat, especially if exposed to it during the painting process.

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It’s best practice to avoid painting a surface that exceeds 90° Fahrenheit, which means that it’s important not to paint in direct sunlight.

Exposure to heat at this level can cause the outermost part of the paint to develop skin before the rest of the paint has dried, causing an uneven drying time that can lead to bubbling.

You may see blistering in small areas that see extended exposure to sunlight over time, which is a relatively minor problem that spot-sanding and paint can fix.

How To Fix Paint Blistering Caused by Heat

If you find your paint is blistering because of heat, it’s a relatively easy problem to rectify. You’ll want to address the problem before you notice more blistering or the paint begins to chip.

Identify the affected area and begin by using a paint scraper to chip away at all the paint separated from the substrate.

After removing the bubbles, sand down the area, to avoid the look of a patchy paint job once completed.

Wipe down the area that you sanded with a wet cloth to remove any dust or paint chips. Allow this area to dry completely before proceeding to the next step.

Once it’s dry, apply a coat of primer. Once the primer has dried, you can reapply paint to the site.

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How Moisture Can Lead To Paint Blistering

If you’ve ruled out wall prep and heat as the cause of your paint blistering, the source is likely moisture.

Moisture is one of the most common reasons for your paint to bubble and can be the most challenging and potentially costly to identify and fix.

It’s especially likely to pose a problem in particularly humid areas of the house such as the kitchen, bathroom, or basement.

Because of the chronic moisture in the air, you may be more likely to see paint blistering than in other rooms.

Paint blistering below the substrate indicates that the moisture is coming from inside the wall regardless of the room.

The moisture from inside the wall is pushing outward, which is why you see multiple layers of bubbling. This blistering cannot simply be patched over but will have to have the root issue addressed. 

How To Fix Paint Blistering Caused by Moisture

Blistering caused by moisture is typically a more serious undertaking. 

If the moisture that caused your paint to bubble was simply from not waiting long enough for your wall to dry before applying paint, you can follow the same steps to fix the area as you would with blistering caused by heat.

You may also want to touch up any caulking to prevent moisture from reaching your walls. Don’t forget to prime first if you need to paint over the freshly caulked area!

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If, however, the moisture is coming from inside the walls, you’ll need to address the overall moisture concern in your home.

In an area such as a bathroom, kitchen, or basement, where there will be more humidity in the environment, you may need to install venting fans.

If you’re not sure whether or not you need to install a vent in these areas, consider getting a hygrometer, which measures humidity levels.

An appropriate humidity level is between 30-50%. If you’re seeing humidity levels much higher than this, you run the risk of your paint beginning to blister.

The venting fans will blow the moist air directly outside, preventing it from sitting in the house, and causing your paint to blister.

If you see bubbling paint in other rooms, you’ll want to call a professional to your home, as this indicates that you have a moisture buildup inside your walls.

This buildup could point to a leak or a more severe problem that you’ll want to get fixed right away.

How To Identify the Cause of Paint Bubbling

Determining if your paint is blistering above or below the substrate is the best indicator in figuring out what’s causing it.

Your substrate is the surface to which you applied your paint — in your house, it’s the wall, including any previous coats of paint that were there before you added any new paint and primer.

If your paint is peeling above the substrate, meaning only your fresh coat of paint is peeling, the cause is likely due to heat or inadequate wall prep.

To fix this, and the affected areas of the wall, clean the wall surface to rid the area of any dust made from sanding, prime, and reapply paint.

If your paint is peeling below the substrate, you can assume that the source of the peeling is moisture-related. 

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Final Thoughts

Paint blistering can be highly frustrating, and it can be challenging to know what’s causing it.

Heat, moisture, and inadequate wall preparation are all leading causes of paint blistering.

If you see a small patch of bubbling peeling above the substrate, you can safely sand down, prime, and repaint the affected area.

If you note that the blistering has permeated the substrate, you’ll need to identify the more significant moisture problem.

Remember to allow adequate drying time whenever you’re adding fresh paint or primer.


Trina Greenfield, Author
SmackDown Media LLC

About the Author:
Trina Greenfield, the owner of SmackDown Media LLC, is passionate about providing information to those interested in the air quality in and around their homes. Trina writes content about things she’s passionate about, such as safe, in-home air, educational platforms for children and adults, as well as all things family-related.