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Common Building Painting Mistakes to Avoid - Inadequate Surface Preparation InspectAPedia®  -     20 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? How to diagnose the cause of failing paint on a building exterior or interior Paint failure diagnosis checklists for the building exterior & interior

This article reviews 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. Readers should also see Paint Failure Case Photographs-SITE and then Paint Failure Case Photographs-LAB, and see PAINT & STAIN GUIDE, EXTERIOR for a guide to the selection and proper application of paints and stains on exterior wood surfaces.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Common Building Painting Mistakes to Avoid

Experts representing paint manufacturers see many field failures of painted surfaces, often arising from a common cause. 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. Paint should be applied at temperatures of 70^o F, (21^o C), ideally, plus or minus 20^o F (12^o C) - unless product specifications state otherwise. A surface should not be painted if its temperature is within 5^o F of the dewpoint 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.

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

BAD PAINTING SURFACE PREPARATION - Improper Surface Preparation Before Applying Paint

• 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.
• using paint to try to fill gaps where caulk should have been applied.
• 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.
• painting over thinly-cracked, or peeling painted surfaces
• painting over old, existing thick, alligatored paint
• painting over dusty or dirty surfaces
• painting over mold (which many sources incorrectly call "mildew")
• painting over oily or other-contaminated surfaces
• 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 effloresence and early paint falures; see PAINT on STUCCCO, FAILURES for details.
• 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.
• 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. Also see Mildewed Exteriors?.
• painting over mill-glazed surfaces such as trim or cedar or pine clapboards. Also see Unfinished Siding & Trim.
• painting over new masonry or new stucco that has not adequately cured
• painting over old oxidized chalky paint or stain
• painting over rot or insect damaged- wood
• painting over silicone caulk (which in many cases is not paintable)
• painting in hot sun or dry wind: painting in sun or wind can be a particular problem when painting new stucco surfaces. See PAINT in SUN or WIND and see PAINT on STUCCCO, FAILURES for details of the problems this causes on stucco.
• painting the second coat before the first paint coating has adequately dried
• painting without reading the manufacturer's instructions for mixing, thinning, surface prep, temperature conditions, etc.
• 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
• surface washing using chemicals or bleach without adequate wash-off of the chemical or cleaner itself
• 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.

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PAINT & STAIN GUIDE, EXTERIOR
  Moisture Impact on Paint
  Exterior Surface Paints
  Solid-Color Stains
  Application of Paints & Stains
  Discoloration Problems
  Extractive Bleeding
  Mildewed Exteriors?
  Semitransparent Penetrating Stains
  Clear & Lightly Tinted Finishes
  Bleaching Oils
  Unfinished Siding & Trim
  Product Suppliers
  PAINT & STAIN LIFE CHART
PAINT FALURE, DIAGNOSIS, CURE, PREVENTION
PAINT FAILURE CHECKLIST
  EXTERIOR CLUES
  INTERIOR CLUES
  SITE HISTORY
  FAILURE INDICATORS
COMMON PAINTING MISTAKES
  BAD SURFACE PREP
  PAINTING SHORTCUT ERRORS
  PAINT OVER MOISTURE
  INCOMPATIBLE PAINTS
  PAINT in SUN or WIND
  PAINT on STUCCCO, FAILURES
PAINT FAILURE DICTIONARY
PAINT FAILURE ANALYSIS LAB PHOTOS
Paint Failure Case Photographs-SITE
Paint Failure Case Photographs-LAB
PAINT LAB SAMPLE PREPARATION
PAINT REFERENCES

• Paint and Surface Coatings, Theory and Practice, R. Lambourne & T.A. Strivens, Ed., Woodhead Publishing Ltd., William Andrew Publishing, 1999 ISBN 1-85573-348 X & 1-884207-73-1 [This is perhaps the leading reference on modern paints and coatings, but is a difficult text to obtain, and is a bit short on field investigation methods - DF]
• Analysis of Modern Paints, Thomas J.S. Learner, Research in Conservation, 2004 ISBN 0-89236-779-2 [Chemistry of modern paints, overview of analytical methods, pyrolysis-gas chromatography signatures of basic modern paints and their constituents, Fourier transform infrared spectroscopy for paint analysis, direct temperature-resolved mass spectrometry, and analysis in practice - technical reference useful for forensic paint science, focused on art works -DF]
• Seeing Through Paintings, Physical Examination in Art Historical Studies, Andrea Kirsh, Rustin S. Levenson, Materials in Fine Arts, 2000 ISBN 99-051835 [ forensic science, technical reference, focused on art works - DF]
• Paint Handbook: testing, selection, application, troubleshooting, surface preparation, etc., Guy E. Weismantel, Ed., McGraw Hill Book Company, 1981 [Excellent but a bit obsolete paint theory and practice, also a bit light on field investigation methods, out of print, available used-DF]
• Art, Biology, and Conservation: Biodeterioration in Works of Art, RObert J. Koestler et als. Eds., Metropolitan Museum of Art, 2003, ISBN 1-58839-107-8
• Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF]
• Understanding Ventilation, John Bower, The Healthy House Institute, ISBN 0-9637156-5-8, 1995 [General building science-DF]
• Dampness in Buildings, Diagnosis, Treatment, Instruments, T.A. Oxley & E.G. Gobert, ISBN 0-408-01463-6, Butterworths, 1983-1987 [General building science-DF]
• "Moisture Control in Buildings: Putting Building Science in Green Building," Alex Wilson, Environmental Building News, Vol. 12. No. 5. [Good tutorial, "Moisture 101" outlining the physics of moisture movement in buildings and a good but incomplete list of general suggestions for moisture control - inadequate attention given to exterior conditions such as roof and surface drainage defects which are among the most-common sources of building moisture and water entry.--DJF]
• "Paint Failure Problems and Their Cure," Daniel L. Cassens and William C. Feist, National Forest Products Laboratory, online via Purdue University, http://www.ces.purdue.edu/extmedia/NCR/NCR-133.html
• "Why House Paint Fails," Mark Knaebe, US FPL, http://www.fpl.fs.fed.us/documnts/finlines/knaeb95a.pdf
• "Why Paint Jobs Fail," http://www.bennette.com/pdf/whyfail.pdf
• "Supplemental Guidelines for Removing Paint From Interior and Exterior Wood Surfaces," US General Services Administration, http://w3.gsa.gov/web/p/Hptp.nsf/0/40aff5a115b6a9e5852565c50054b4f4?OpenDocument
• "Common Paint Problems," http://www.parkerpaint.com/Common%20Paint%20Problems.html illustrates common paint failures - though their images and text appear to have been stolen from PPG - see http://www.ppg.com/getpaint/etraining/solver/exterior.html which catalogs paint failures and causes
• "Paint problem solver" from Lowes, http://www.lowes.com/lowes/lkn?action=howTo&p=Improve/PntPrbSlv.html&rn=RightNavFiles/no.html
• "Mill Glaze: Myth or Reality," R. Sam Williams, Mark Knaebe, US FPL, http://www.fpl.fs.fed.us/documnts/finlines/willi01a.pdf
• http://www.paintlab.com/failure.html is a lab offering paint chip failure analysis
• PPG Exterior Failures http://www.ppg.com/getpaint/etraining/solver/exterior.html

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More Information on Building Diagnostic Inspections and Repairs

• Exteriors, Landscaping, & Siding - Inspection, Repairs, Product Failures

• Quotes in the opening text of this document are from the encyclopedic but not quite complete paint website: PPG Exterior Failures http://www.ppg.com/getpaint/etraining/solver/exterior.html

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