Prepare for the Task
Exterior PaintProbably the single most important aspect of exterior house painting, besides quality of exterior paint, is the quality and thoroughness of preparation; readying the house surface prior to painting.
This directly affects the quality and durability of resulting exterior paint finish. A poor quality exterior house painting job can require attention again in as little as 3 years; a quality job done by a professional house painter can last up to 20 years.
Evaluating Surface Painting Conditions
When evaluating a surface for exterior house paint, condition of existing paint surface as well as type of substrate will dictate what needs to be done. Is the substrate wood, stucco, metal, or wood substitute? Bare wood exposed to weather for any length of time, such as a window sill, may be rotted; requiring replacement before painting.
There are three levels of existing paint condition severity:
- Class I minor paint damage and soil accumulation; usually requires no paint removal.
- Class II visible break down and cracking of top layers of paint; involves some paint removal.
- Class III significant paint failure; break down and cracking of multiple layers of paint; requires total paint removal to bare substrate.
Because different areas of the house surface are subjected to varying conditions, different class conditions may exist throughout the structure. Therefore, careful inspection is crucial in making an accurate evaluation.
Removing the Dirt
Class I conditions include soiling; such as dirt, insect or animal nests, soot, pollution, and cobwebs. They may also include mildew, chalking, or staining.
Soiling can be cleaned using mild detergent and a garden hose; use a medium soft bristle brush to scrub stubborn soils. Using a high pressure power wash will be quicker and more effective.
Mildew is caused by lingering moist conditions. If possible, remove the cause; such as low hanging tree branches etc. Mildew can be removed using a non-ammonia detergent and bleach solution; one cup detergent, one quart bleach, and one gallon warm water. Note: when repainting, consider using a mildew-resistant paint primer.
Chalking; a powdery substance on the paint surface caused by the oxidation of volatile oil content in the paint when exposed to high levels of ultra violet sunlight. Remove chalking by gently scrubbing the area using a mild detergent and brush; rinse with a garden hose. When thoroughly dry, re-paint using a non-chalking paint.
Staining of a painted surface is usually one of two types: rust the oxidation of nails exposed to moisture, or the reaction of moisture and resins in the wood underneath. A common occurrence with redwood or cedar.
Nails should be hand sanded and coated with a rust inhibitor primer, followed by at least 2 coats of paint. Resin staining can be cleaned using a mixture of equal parts denatured alcohol and water; rinse thoroughly, and dry. When completely dry, seal using 1-2 coats of stain blocking primer. Allow 48-hours between coats, and then paint as you normally would.
Removing Minor Damage
Class II conditions include crazing (fine cracking), intercoat peeling, solvent blistering, and wrinkling.
Crazing is caused when multiple coats of paint become hard, dry, and brittle, and can no longer expand and contract with the substrate material. This results in interconnected hairline cracks in the top layer of paint. Hand or tool sanding followed by a fresh coat of paint will seal moisture from the cracks, even though cracks may still show.
Intercoat peeling; usually the result of either improper painting preparation, or incompatibility between coats of paint, such as latex over oil based. The surface should be carefully scraped to remove all loose paint, and then thoroughly cleaned. Apply a high quality oil based primer once completely dry, and then either an oil base or latex paint.
Solvent blistering. A rarely-seen error in paint application, caused when solvent-rich paint is applied in direct sunlight. The surface dries too quickly; solvents are trapped beneath the dried film. As they come to the surface, they cause blistering.
Any blisters should be cut open to determine whether they are caused by moisture or solvents. If another layer of paint is visible beneath, the problem is probably solvent blistering; if bare wood is underneath it is likely due to moisture. This can be remedied by scraping or sanding to a sound surface, and repainting; avoid painting in direct sunlight.
Wrinkling another error in paint application caused when the top layer dries before the layer underneath. This can be caused by several factors:
- Applying paint too thick
- Not allowing adequate drying time between coats
- Improper brushing
- Applying paint in excessive heat conditions.
Wrinkling is corrected by scraping or sanding to a smooth finish, and then repainting following paint manufacturer recommendations.
Removing Excessive Damage
Class III conditions consist of peeling to bare substrate, or severe cracking or alligatoring. These conditions require complete removal of existing paint.
Peeling most commonly occurs on wood substrates; caused when moisture collects between the paint and substrate, greatly affecting paint adhesion. Peeling usually begins as blisters that accelerate as moisture swells wood substrates. This breaks down adhesion, resulting in cracking and peeling.
The first step in treatment is to eliminate the moisture problem or repainting will be futile; the problem will reoccur. Once the moisture problem has been solved, sand or scrape to completely remove paint; wipe down the surface, and then apply primer and repaint.
Cracking and Alligatoring is advanced crazing; moisture intruding through cracks, breaking adhesion of the paint to the substrate. The resulting vertical and horizontal cracks in the paint resemble reptile skin, hence the term alligatoring.
When this has progressed to bare wood, or if flaking is present, paint will have to be completely removed. Methods include scraping, use of electric heat plate or electric heat gun, or chemical strippers. Once old paint has been removed and the surface cleaned and dried, apply primer to bare wood. Allow ample cure time, and then re-paint.
When in Doubt, Call a Professional
If dealing with these type conditions and procedures sounds complicated and time consuming, you are right; it is. Seeking the services of a painting contractor or house painting contractor can be the best solution for all these problems.
When it comes to identifying and addressing various problematic conditions, a professional painter can quickly identify each, and take the necessary action. An exterior painting contractor also can give helpful insight when it comes to selecting paint color, developing an overall paint color scheme, and type and grade of paint to achieve maximum durability.
One of the best places to find a reliable, experienced exterior painting contractor in your area is at TrustedPros.com
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Homeowners can sign up for free, with no obligation whatsoever, and post their exterior paint project online. The project is immediately made visible to service providers in their community; local contractors provide competitive bids for the project.
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