Peeling paint occurs for a number of reasons, however, the most common causes are incorrect preparation, application or moisture presence. Sources of moisture can vary. Determining the cause of failure will depend on many factors including: the type of surface painted, the time painting took place, and what the current condition is (i.e.: applying paint during abnormal weather or applying the wrong type of paint to a particular surface). Prior to painting bare wood, the surfaces should be dry and at the right moisture level. Proper stopping and knotting should be conducted before the application of the primer.
Moisture:
(1) The largest sources of moisture are often found in the basement and crawl space areas. One remedy is to cover bare soil with polyethylene plastic. Sealing air leakage from other areas including chimneys and other attic areas with non-combustible material will reduce the tendency of the house to pull moist air in from outside;
(2) Another significant source of interior moisture is in the bath area. Tiling the bath or shower enclosure and providing an exhaust fan to the outside (not into the attic or soffit areas) will help to control & remove moisture. Interior moisture is also generated by dishwashers, humidifiers and cooking where no vapor barrier is present behind the walls. The use of a "vapor barrier" paint may be recommended for use inside the house to reduce moisture penetration of walls;
(3) If paint is peeling away along the lower several feet of the house exterior, many times the problem is being caused by rain run-off splashing on the ground, walkway, or deck. A properly installed rain gutter system will reduce this moisture loading.
Preparation for Painting:
(1) Once the moisture problem is corrected, loose paint must be removed and the surface cleaned (Note: Caution must be taken if lead paint is present. See additional comments about lead paints under Section VII in this booklet);
(2) If mildew is present, it should be cleaned with detergent, scrubbed with a mixture of bleach and water (1 part bleach to 3 parts water), and then thoroughly rinsed. CAUTION: the area MUST be well ventilated.
(3) When painting the outside of the house, it is advisable to wash the entire house prior to painting. The wood must be thoroughly dry before painting. If commercial cleaning equipment is used, allow several weeks for drying.
Painting:
(1) Bare wood should be painted with an oil or alkaloid primer, and two topcoats of paint are recommended. The second coat will generally double the life of the paint job. Do not exceed two weeks between primer and topcoat application;
(2) Consult your local paint supply store for more specific advice about specialized paint systems and their respective application methods;