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Alligatored paint (C) Daniel Friedman Common Building Painting Mistakes to Avoid
26 ways to get a bad paint-job on a building

  • PAINTING MISTAKES - CONTENTS: 26 examples of inadequate surface preparation that lead to building paint failures. What are the most common painting mistakes that we should avoid when painting a building?
    • POST a QUESTION or READ FAQs about building exterior or interior paint job mistakes and paint failiures - how to avoid paint problems on buildings
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Paint job mistakes that result in early paint failure:

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

We include photographs of paint failures on buildings and more photos of forensic paint laboratory examination of samples of failed paint useful to assist in diagnosing the probable cause of each type of paint failure. Our page top photo shows a horrible paint job on a building exterior: the painter simply painted over loose, alligatored paint.



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Common Building Painting Mistakes to Avoid

Photograph of  peeling paint on a building exterior - can you diagnose this failure by eye?Experts representing paint manufacturers see many field failures of painted surfaces, often arising from a common cause.

[Click to enlarge any image]

But getting a clear answer from these professionals can be tricky: the painting contractor is their customer, not the building owner.

Therefore, while most paint failures are due to poor surface preparation or painting in improper conditions of temperature or moisture, the "expert" may be reluctant to say so.

Importantly, other paint failures are due to construction errors, building ventilation or vapor barrier errors, building leaks, or improper maintenance. It is important to understand why a paint failure occurred before re-painting a building.

Otherwise the expense of a new paint job may be wasted.

"Improper or inadequate surface preparation is by far the most common cause of house paint failures such as blistering, peeling and staining. If the new paint is separating from the old coat of paint, it is most likely due to chalking or some contaminant on the old paint that prevents the new paint from penetrating and binding to the old painted surface.

If the peeling failure is down to the bare wood, it is most likely that the problem is a result of too much moisture within the wall, forcing itself out, taking the entire paint film with it."

"Over 65% of all paint failures can be attributed to poor or improper surface preparation. Two of the major causes of paint failure on exterior wood surfaces are either moisture passing through the substrate from the interior, or exterior sources of moisture getting behind the paint film. Temperature and humidity have major effects upon drying and ultimately upon the characteristics of the paint film. These effects will always determine the actual appearance and performance of the paint itself.

Photograph of  peeling paint on a building exterior - can you diagnose this failure by eye?Paint should be applied at temperatures of 70o F, (21o C), ideally, plus or minus 20o F (12o C) - unless product specifications state otherwise. A surface should not be painted if its temperature is within 5o F of the dew point or the relative humidity is above 85%." -- PPG Exterior Failures.

The follow sections of this document form a checklist of building and site conditions leading to paint failures (such as peeling paint, blistering paint, chalking paint, cracking or alligatoring paint, or bleeding and stains through paint--terms defined below).

The focus is on failures of painted wood surfaces on building exteriors but the paint failure diagnostic procedure can be generalized to other surfaces inside and out.

The three key steps to successful painting are

1. Prepare the surface,

2. Prepare the surface,

3. Prepare the surface.

- DF (moderator) and a panel of experienced house painters at ASHI ca1988 Paint Failures Seminar. Also see PAINT SURFACE PREPARATION.

But other than inadequate surface preparation, here are some other very common house painting mistakes:

BAD PAINTING SURFACE PREPARATION - 26 Painting Mistakes That Mean a Bad Paint Job with a Short Life - causes of early paint job failure

  1. Removing only the obviously-loose paint, leaving poorly-secured paint, leaving thick edges of old paint where blisters or old peeled paint were inadequately removed.
  2. Using paint to try to fill gaps where caulk should have been applied.
  3. Using a spackling compound or filler intended for holes or cracks to "smooth" large building surface areas (skim coating) such as skim coating in order to apply paint over alligatored or poorly-adhered old paint. More thickness of fillers, paints, primers,or magic gluey coatings on the surface of un-sound paint are unlikely to work. A case study of this foul-up is at PAINT FAILURE CASE PHOTOS, SITE.
  4. Painting over thinly-cracked, or peeling painted surfaces
  5. Painting over old, existing thick, alligatored paint
  6. Painting over dusty or dirty surfaces.
    See PAINT SURFACE PREPARATION
    and for mold (or "mildew") or algae or other dark stained surfaces
    see SIDING, WOOD CLEANERS, STAINS, PAINTS
  7. Painting over mold (which many sources incorrectly call "mildew"). Painting over moldy surfaces without adequate cleaning and surface preparation such as power washing, disinfection, and light sanding, likely to lead to rapid mold re-growth in the paint and possibly to a paint adhesion failure, even if a paint "mildewcide" or fungicidal additive was used.

    Even if you clean the surface, if you paint without correcting the cause of the stain (shade, trees, moisture) means those stains will recur, growing right through the new coating.
    See SIDING, WOOD CLEANERS, STAINS, PAINTS for cleaning advice and for advice about choosing the right type of stain or paint.

    Also see Mildewed Exteriors?.

    Parmetol, a wood preservativerecommended by the manufacturer was used as a fungicidal additive to paint on the Blue Poplar wood sculpture in Amsterdam, by sculptor artist Mari Shields whose huge wood tree sculptures and stunning works can be found at a number of locations listed at her website: http://www.marishields.com/[ - art conservation consult DF-artist MS 2010]
  8. Poor paint job (C) Daniel Friedman


    As we discuss
    at PAINT FALURE, DIAGNOSIS, CURE, PREVENTION, our photo (left) shows a new paint job that failed before the job was even finished, on a historic property: the Justin Smith Morrill Homestead in Vermont.

    While most of the paint failures on this building were due to use of improper paint or defective product, here we saw peeling and loss of adhesion over moldy wood.

    A combination of failure to properly clean the wood surface before painting, painting under too hot or too wet conditions, and failure to use an effective primer and properly formulated top coat can conspire together to give a messy paint job failure on some projects.

  9. Painting over oily or other-contaminated surfaces
  10. Painting over high pH surfaces on stucco, such as new stucco that has not adequately cured or stucco that needed additional wash and surface neutralization can cause white blooms of efflorescence and early paint failures;
    see PAINT on STUCCO, FAILURES for details.
  11. Painting over glossy hard paint surfaces without adequate preparation such as light sanding or use of a chemical de-glosser, likely to lead to an adhesion failure.
  12. Painting over mill-glazed surfaces such as trim or cedar or pine clapboards.
    See PAINT SURFACE PREPARATION

    Also see Unfinished Siding & Trim.
  13. Painting over new masonry or new stucco that has not adequately cured.
  14. Painting over old oxidized chalky paint or stain
  15. Painting over rot or insect-damaged  wood
  16. Poor prep trim paint job (C) Daniel Friedman


    As we discuss
    at PAINT FALURE, DIAGNOSIS, CURE, PREVENTION, our photo (left) shows a new paint job over old rot.

    It looks as if the painter used a rather soft wood filler to try to repair the rotted window sill, and if you look closely (click the image to enlarge it) you'll see that the paint is already coming off - months after this costly renovation.

    Where sill rot is limited, rather than replacing the entire sill or frame, we find it easier to cut out and replace a rotted window sill by piecing in a custom-cut repair segment, perhaps using treated wood (let it dry before painting) glued in place.

    We have also made occasional use of wood restoration epoxy products such as those made by Abatron, Inc. to restore and save valuable trim that would be costly to replace. But slopping on some putty and paint, as was done here is not a durable job.

  17. Painting over silicone caulk (which in many cases is not paintable)
  18. Painting in hot sun or dry wind: painting in sun or wind can be a particular problem when painting new stucco surfaces. See PAINTING in SUN or WIND
    and
    see PAINT on STUCCO, FAILURES for details of the problems this causes on stucco.
  19. Painting the second coat before the first paint coating has adequately dried
  20. Painting without reading the manufacturer's instructions for mixing, thinning, surface prep, temperature conditions, etc.
  21. Soaking building cavities: surface preparation for painting by improper use of a power washer: spraying "up" on a clapboard building forcing water into the building wall cavities, (risking hidden mold contamination or a moisture problem leading to paint failure), or spraying too-close to the building surface, causing gouging and undesirable loss of surface material
  22. Surface washing using chemicals or bleach without adequate wash-off of the chemical or cleaner itself
  23. Painting on wet surfaces - failure to measure moisture levels or measuring only the "dry" areas but painting over other wet areas of a building. Also
    see Moisture Impact on Paint.
  24. Painting over incompatible old paint - leading to poor adhesion, wrinkling, cracking, paint fall-off.
    See INCOMPATIBLE PAINTS.
  25. Painting with the wrong type of paint for the surface or environment, such as using an interior paint outside.
    See INCOMPATIBLE PAINTS.

Poor prep trim paint job (C) Daniel Friedman

  1. Sanding with a grinder carelessly, leaving sanding marks and gouges that ruin the surface and telegraph through the new paint job - may not reduce paint adhesion but may result in a cosmetic issue with the work.
  2. As we discuss
    at PAINT FALURE, DIAGNOSIS, CURE, PREVENTION, our photo (left) shows the condition of a nearly brand-new paint job on an older home in Poughkeepsie, NY.

    We noticed that old paint was left on the surface with no feathering of the edges of the few spots where paint had been removed or had fallen off before the paint job.

    We noticed also that the painter tried to "seal" the loose paint by globbing on plenty of new paint - see that drip running down the trim board?

    Finally, we noticed that this new paint job was already failing - the split in the paint visible in the lower portion of the photograph.

    This paint job will have a shorter life than if the surface had been stripped, but then the painter (and owner who was selling his home) avoided a much higher cost of stripping lead-containing paint from an older building.

Poor prep trim paint job (C) Daniel Friedman

  1. Painting too thick: slopping on paint that runs down walls (see above and below)
  2. As we discuss
    at PAINT FALURE, DIAGNOSIS, CURE, PREVENTION, our photo (left) shows the result of many coats of paint on a home built in Dutchess County NY in the 1700's. This was some of the thickest paint we have found on a building exterior.

    No tests for the presence of lead paint are necessary in a case like this - you know that lead paint is present. Y

    ou also can see that this paint job is cracking and that paint has been falling off of the building between paint jobs that involved little or no surface preparation.

  3. Painting too thin: over-thinning paint to extend its coverage dilutes the binders so that even if the new paint job looks great it may wear or fail prematurely

For a description of proper painting procedures
see PAINT SURFACE PREPARATION.

Odors from paints and low-VOC or zero-VOC paints are also discussed
at ODOR DIAGNOSIS CHECKLIST, PROCEDURE.

Painting Mistakes Articles

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Continue reading at BAD SURFACE PREP or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see PAINT FAILURE CASE PHOTOS, SITE and also PAINT FAILURE CASE PHOTOS, LAB

Or see PAINT FALURE, DIAGNOSIS, CURE, PREVENTION - home

Or see PAINT & STAIN GUIDE, EXTERIOR for a guide to the selection and proper application of paints and stains on exterior wood surfaces.

Or see SIDING, WOOD CLEANERS, STAINS, PAINTS how to remove stains on siding & how to choose the proper paint or stain coating

Or see VOCs VOLATILE ORGANIC COMPOUNDS 

Suggested citation for this web page

PAINTING MISTAKES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

INDEX to RELATED ARTICLES: ARTICLE INDEX to ARTICLE INDEX to PAINTS & STAINS & FAILURES

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