House Paint Problems - # 4, Chalking

Symptoms: Chalking


Chalking is identifiable as a fine chalky powder that forms on the surface of a paint film. Although some chalking is a normal way paints self clean when exposed to the sun and rain, excessive chalking can be a paint failure. In dry arid climates where there is little rain, chalking can become excessive. Chalking is actually the paint pigment released by the paint binders which have been broken down by exposure to the weather. Chalking is especially typical of very light colored flat paints, especially lesser quality oil based paints containing high levels of pigment extenders. When chalking gets severe it may run off onto and stain surrounding construction as in the above photo.

Potential Causes:

•Use of cheaper quality exterior paint containing high levels of pigment extenders.

•Improper paint was used in an exterior application (such as an interior paint).

•Lower quality factory finished aluminum siding.

•Over-thinning paint.

•Not properly sealing a porous surface before painting.

Possible Repairs:

•Chalking is considered dirt and must be removed before repainting.

•Remove chalking by power washing or scrubbing with a trisodium phosphate cleaning solution and rinse with clean water.

•Let dry and paint with a high quality latex house paint.

•To clean brick areas stained by chalking runoff the masonry should be scrubbed with a specialized masonry cleaning solution. If staining persists, a professional cleaning contractor may be required to clean the brick.

House Paint Problems - # 3, Efflorescence

Symptoms: Efflorescence


A problem of painted masonry construction, efflorescence is identifiable by crusty white salt deposits that bubble through the paint film from a masonry structure. Salts in the brick or concrete become dissolved with water and then leach to the surface as the water evaporates.

Potential Causes:

•Poor paint surface preparation where prior efflorescence was not entirely removed and washed before the surface was repainted.

•Heavy moisture migrating through exterior masonry walls from inside the home.

•Inadequately waterproofed basement walls allowing ground water penetration.

•Painting masonry construction before the concrete or mortar had adequately cured and dried out.

•Cracks in masonry wall or poor tuckpointing is allowing water to get behind masonry wall.

Possible Repairs:

•If moisture is getting into the masonry wall eliminate source of moisture by properly tuckpointing any cracks or missing mortar in the wall or patching concrete with a latex concrete patch, clean out gutters and downspouts, caulk joints around windows and doors with a butyl rubber caulk.

•If moisture is migrating through the wall from the outside (e.g., basement wall), apply waterproofing to outside of wall.

•Remove all efflorescence and loose flaking, chalking paint with a wire brush, scraping or power washing before repainting.

•Clean area with a trisodium phosphate cleaning solution and rinse with clean water.

•Let completely dry and paint with a high quality latex house paint.

House Paint Problems - # 2, Alligatoring and Checking

Symptoms: Alligatoring and Checking


"Alligatoring" is a failure in the paint film where it takes on a cracking pattern of deep relief resembling a reptile's skin, such as that of an alligator. "Checking" is a similar failure but is less severe and is characterized by long, fairly evenly spaced cracks in the paint film having shallow relief or depth. Occasionally checking may become severe in some areas and a deeper crack or split in the paint will occur.

Potential Causes (Alligatoring):

•A second coat of paint was applied over a first coat of primer or paint base coat before it dried.

•A second coat of paint was applied over an incompatible paint such as a glossy paint or a hard oil enamel over a latex based paint.

•Oil based paints naturally aging and losing the little elasticity the paint film originally had, therefore it cracks due to fluctuations in temperature.

Potential Causes (Checking):

•Natural aging of several layers of older oil based paint. As the material having been painted shrinks and expands over time (usually wood), the paint has to move and as it loses elasticity, it checks.

Possible Repairs:

•The fix is the same for both problems.

•Remove the old paint, sand, prime and repaint with flexible latex based paint.

•Use high quality latex paint.

House Paint Problems - #1, Blistering

Symptoms: Blistering


Blistering paint is identified by small to medium sized bubbles or blisters under the paint film and is most common on wood siding and trim.

Potential Causes:

•Painting in direct sunlight on a hot substrate (surface being painted) which traps solvent vapor as the paint dries too quickly.

•Painting when the wood is damp causing trapped moisture to expand the paint film.

•Dew, rain or very high humidity after latex paint has dried if the latex paint is of lower quality or the substrate surface preparation was inadequate.

•House moisture escaping through the walls due to improper house ventilation.

Possible Repairs:

•Scrape away blistered paint and sand to bare wood.

•Let wood completely dry.

•Sand, prime and paint in non-direct sunlight and non-humid conditions.

•Use high quality latex paint.

•If due to lack of home ventilation, corrective repairs must be made to properly ventilate the home's walls, roof and eaves, bathrooms, etc.

•Check and repair any loose or missing caulking around windows and doors.

•Consider providing siding ventilation.