Why Does the Paint on My House Bubble?

Why Does the Paint on My House Bubble?


Recently I had two different conversations that essentially asked pretty much the same thing.

“Tom, why does the paint on my house bubble?”

The answer to each was a question from me.

“When you see it bubbling, what else is happening at that time?”

Although there are numerous reasons as to why paint might bubble, I am going to address the two specific reasons why the paint was bubbling in these particular circumstances that I was asked about.
In the first example, the individual mentioned that she was in the process of painting her home and everything seemed fine for a week, but then about a week after it was done, she noticed that the house seemed to be bubbling.
After speaking with her further, there were no obvious signs of moisture involvement and it only seemed to bubble in areas that the sun shined on and only when the sun was actually shining on it.

In this case, I believe that something two-fold was occurring.



I believe that the paint coating that was applied was not fully bonded to the coat beneath it (this could be for several different reasons).

Typically it takes at least 30 days for paint to fully cure. Although these days, paint may dry to the touch fairly quickly, it still does not maintain its full hardness for some time afterward.

If a paint coating is not fully bonded to the coating/surface below it and the coating has not yet achieved its full hardness (/tightness), a little heat from the sun will typically pull any air in between the coating and the surface directly below it to a point (or several points…) and cause it to bubble.

In the second example, after asking the person some questions about the circumstances of their issue, it seemed that somehow moisture was working its way in behind the paint coatings.

The coatings had already been on the house for quite some time, so a coating needing to cure did not appear to be part of the problem.

This particular home was quite old (about 175 years old or so) and sometimes in older homes, moisture can creep behind places in peculiar ways.

When the moisture crept behind the wooden clapboard that the paint coatings were attached to, as the surface heated up, the moisture would tend to be pulled and gathered in certain areas to points which would create bubbles.



In fact, if you were to pop one of the bubbles, water would come out of it.






To “trick” the moisture, we ended up breaking the seal at the butts of the clapboards and using a wedge (basically a tiny shim) directly behind the areas where the bubbles were forming.

The idea with this is that as the climate moves to pull the moisture to the various points, instead of trying to find its way out through the paint coating in the front of the clapboard, it would have a much easier escape on the backside of the clapboard.

Though these are just two examples, paint coatings could form bubbles on the surfaces they are attached to for a wide variety of reasons.

If you are experiencing bubbling on your exterior paint coatings and haven’t the foggiest idea as to exactly why it is happening, please feel free to reach out to our office and set up a conversation with us and let’s see if we can work together to figure it out!

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