Q&A about paint failures on stucco walls, cause, diagnosis, cure & prevention methods:

Answers to frequently-asked questions about paint failures on stucco surfaces.

This article series describes common building exterior & interior painting mistakes when painting on modern stucco building exteriors, describes how to diagnose paint failures on buildings, and outlines a procedure for diagnostic field inspection & lab testing of failed painted surfaces.

Stucco Wall Paint Failure FAQs

These questions & answers about stucco paint job failureswere posted originally at PAINT on STUCCO, FAILURE

Question: will painting over efflorescence spots fix the problem?

(June 16, 2017) Mimi Petersen said:
Hello,
Our home is 4 years old. After the very heavy rains here in California, we have lots of efflorescense on our "Chocalate" brown house.

The builder folks came out and tried vinegar and water on some spots, but no luck. They felt some of the spots were burned on and trying to clean off would not remove.

They are suggesting they spot paint the spots. If in the event they don't blend they say they will repaint the entire walls.

Will painting over these spots resolve the problems? Our understanding was this is a leaching process and can reoccur until it is done. So would the spots potentially leech again? Thank you.

Reply:

Painting over a properly dried stucco wall to cover prior stains of any sort might work if you first feel the circus with a lacquer primer sealer. However if there is water inside the wall cavity the problem will return.

Also check the wall pH before re-painting.

See

RUSHING the STUCCO PAINT JOB

pH of the STUCCO SURFACE

PAINTING on WET STUCCO

to better understand the situation and the cure for it.

Question: painter water-blasted to raw cement then painted: now effloresence

(July 25, 2015) Valerie Fraser said:

We have a stucco home that was painted by a Master Painter 4 months ago. As prep work they high power water blasted taking off paint back to raw cement and in some areas blasted away structure.

We were shocked.

Immediately after the finishing and after 1st rainfall we noticed all of our windows had a white film (the house was painted white). I thought this was normal at first

- it is now 4 months later and after continued washing of my windows, I am seeing a continual film & white streaking on my windows

- I can take a a clean soft cloth and wipe the exterior walls and rinse in a clear water bow

l- when you compare a glass of water from the tap to the water I rinsed my cloth in- there is a night and day difference

- one glass is clear the other a cloudy whitish.

We don't believe this to be just a detergent in the paint (as we've been told by the painter), we've had ample rainfall and the process is contiual

- we definitely believe something is wrong... any suggestions? Many thanks for your help :)

Reply: painting over wet walls means trouble is likely

From your description it sounds as if the surface was painted when still wet. Especially after power-washing as you described ten days or more may have been needed, depending on weather, for the walls to dry adequately before painting.

Once the walls have dried and stabilized it may be possible to clean (mechanically), apply a sealant, then re-paint.

Question: when is stucco ready to paint?

(Apr 24, 2011) Anonymous said:

how no the estucoo is redy

Reply: When measuring pH on a wall, don't just measure the obviously "ok" areas

How do I know when the stucco is ready for painting - cuando sabemos que el estucco esta lista para pintar?

Be sure that the stucco has adequately cured before painting. Typically the stucco must cure for at least ten days to two weeks before it can be painted. The pH of cured stucco is normally below 11. If the stucco is still "hot" - not cured - painting it risks early paint failure.

Make proper moisture & pH measurements of the stucco before painting. High pH (over 11) stucco is likely to give a problem for the new paint job.

When measuring pH on a wall, don't just measure the obviously "ok" areas, measure where you see fine cracking, early signs of efflorescence, areas of paint failure in a primer coat, and in representative sun-exposed and shady wall areas.

Different exposures of a building's stucco exterior may cure at different rates because of variations in sunlight and wind. Follow the pH and moisture test and level recommendations of the paint manufacturer.

Question: how long should stucco dry after power washing & before painting?

(June 29, 2012) Debbie said:

How long should an existing stucco surface be allowed to dry after power washing before painting? This is in Arizona, where the temperatures have been close to 110 degrees

. If it was power washed in the morning, say around 9am or 10am, could it be painted the same day?

I ask because I had previous visible damage from when the original contractor came to fill the cracks.

The company I hired had told me that when they were finished I would not be able to still see these cracks. They finished that side today, and I can still see them. The painter told me that nothing he could do would make them no longer be visible. Is this true?

Reply:

Debbie I don't think that time, alone, is the safest way to decide that a surface is dry enough to paint; experts measure moisture, and not just in the most-dry center of the field but rather, measure in locations most likely to still be damp - intersections, low on walls, shaded sections.

Also as you'll read at PAINT on STUCCO, FAILURE, hot sun can be a problem too.

About being promised one thing and delivered another, it sounds as if your first conversation was with the salesman and the second with the painter. I would not pay for the job before being satisfied.

Indeed it is more difficult to make cracks "disappear" but it is certainly possible - my painter has been successful.

Differences in wall texture in and out of the crack repair area are often the problem;

Send along some photos if you can, we may be able to comment further.

Question: Black lines in caulk: Luxon XP by Sherwin Williams, on Florida Stuccoed Houses

(Oct 24, 2014) Patty said:

I recently had two stucco houses re-painted in Jacksonville, FL in Nov 2013. The homes were built in 2006.

Less than a year after re-painting, both houses look like haunted houses. By that I mean that the cracks caulked by the builder look black; in order words, there is black lines showing up exactly where the painted caulked.

The builder used Luxon XP by Sherwin Williams, which I had used on another stucco house in 2011 with no issues (different builder for the house repainted in 2010).

I had a stucco expert examine the stucco and he said there is nothing fundamentally wrong with the stucco itself. Supposedly the builder is a good builder. But something went wrong, and I am wondering if anyone has seen this problem.

Reply:

Black lines where painted surfaces caulked: typically I'd expect to find mold growth in the particular caulk that was used.

Try removing it and using a mold-resistant caulk before you re-paint. This is a caulk and mold problem, possibly a moisture entry problem, but probably not a paint failure per se.

Question: don't paint stucco?

(Oct 31, 2014) George said:

my wife says no to painting stucco- I say yes, if properly prepared and dry. I have painted very dry stucco that we watered down first and then sprayed a coat on- let it set up, and then back rolled.
What's your opinion?

Reply:

George,

Painting stucco is widespread, worldwide. The article PAINT on STUCCO, FAILURE describes some of the snafus that prevent the paint job from satisfactory results, including painting over wet or un-cured surfaces.

Question: bubbling paint failure on 10 year old stucco paint job

12/12/2014 Dave said:

I have a stucco home that is 10 years old and was painted with a Kelly Moore elastomeric. The house was built and painted by a respected contractor, but I have no way of knowing if they made mistakes. 10 years later the paint is failing; after every rain it bubbles and peels off in sheets.

I try to repair sections and the repaired areas peel off at their old edges. The cost to mechanically or chemically remove this love is around $15k - $20k

. I went to my local Kelly Moore and they said "we didn't paint the house so its not our problem". I don't know what to do. I am finding most painters love this stuff, but don't have experience for how to handle it after a decade. Any advice would be greatly appreciated.

Reply:

Dave

I'm sympathetic to frustration with the paint failure but add that it's not unusual to see a failure occurring after 10 years of service.

My OPINION is that if the painter made mistakes that would explain a paint adhesion failure those mistakes would normally show up very quickly, often before the whole paint job is finished and certainly in the first year.

Before beginning any repair or re-paint job, let's make ourselves confident that we understand the bubbling and peeling that you are seeing

. It is most likely caused principally by water or moisture getting behind the paint. What we want to know is where water is entering and why, and while we're at it, we want to be sure there is not an uglier problem in the building wall cavities.

Leaks into an EIFS or synthetic stucco covered building are particularly egregious as water is trapped in the cavity inviting mold, insects, rot.

Water may get behind paint because of paint porosity (normal aging, normal wear, bad mix, wrong paint), cracks, leaks into the wall at wall openings, or something else.

If you pull off a bubbled section of paint and examine its back side under high magnification and find fibers or particles from the stucco then the paint is being pushed off by water.

If you find the back side of the paint chip is clean then the paint is suffering an adhesion failure (that has a different set of explanations). I expect you to see the first case.

If you can send me some sharp photos of all sides of the home and closeups of the failures and of areas where paint has come off or been removed I can comment further.

Use the email at our CONTACT US link found at page top or bottom.

Proper repair means proper prep before re-painting - which can begin when we understand the failure cause. At a minimum, all loose bubbled paint is removed, edges of the removed area are sanded or feathered to reduce sharp water-catching edges, a primer is applied, and the building is re-painted. But first we want to be sure there are no leak sources to be fixed.

(Feb 11, 2015) Dave said:

Hello - just wanted to follow up on my bubbling elastomeric problem. In almost every area where it is failing it looks like it was a second coat that pushed off via moisture behind it.

I think the original coat was faded and dull and the owner repainted a second coat prior to sale. The original coating seems to stick to the stucco just fine.

So looks to me like the coating was too thick and couldn't breath. If this is the case - isn't my only option to remove everything and start over?

After a good rain the last two months it looks like a zombie house.

Reply:

Sometimes too incompatibility between paints, or the solvent in the new coat, causes problems with the prior coating and can lead to separation.

But usually the pattern of failures will tell us something. A paint incompatibility ought to produce large, more uniform problems in the coatings, not small pinpoint or tiny bubble failures. Maybe.

Thanks for the follow-up. I look forward to seeing photos, lab reports, cross-sectional analysis.

Question: indoor formaldehyde problem in painted stucco house blamed on exterior paint

(June 14, 2015) Rita said:

Elastomeric paint was applied in June of 2014 to a fully power washed (took off many layers of old latex) 1920s stucco home. There is no evidence of paint failure HOWEVER there is a serious formaldehyde problem throughout the house. This was noted after rain this year (Jan 2015, first rain since the paint was applied).

The odor now varies with increases in heat/humidity. Have had numerous professionals who have ruled out everything (mold, moisture, household products, HVAC, flooring, etc) except the new paint. No other recent painting, repairs, carpet, construction, remodeling, etc.

Have lived here since 1982. Now that I know what it isn't, how do I fix this off gassing? ... if that's what it is? Do I have to remove the paint? Tear out the interior plaster walls? Remove the stucco? Can't seem to find a professional who has knowledge of construction AND air quality remediation. Located in the SF Bay area. I've been trying to solve this for 6 months now.

Reply:

Rita

I would want to know first how your professionals demonstrated that indoor formaldehyde level was due to an exterior building paint. I'd want objective data not just speculative opinion. Not until we know the source would I consider addressing the problem.

See FORMALDEHYDE HAZARDS - home - for more information on formaldehyde sources, testing, remedies in buildings.

Also see ODOR DIAGNOSIS CHECKLIST, PROCEDURE for help in tracking down odor and gas sources in buildings.

...

Continue reading at PAINT on STUCCO, FAILURE or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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