I am always surprised when I stumble across great information for homeowners in unlikely places. In the latest instance, it is the U.S. Department of Agriculture's Forest Service, Forest Products Laboratory with its comprehensive report on why house paint fails.
The prospect of painting even a small building is one of the more involving and expensive improvement projects a homeowner can take on themselves. And many opt to leave it to professional painters.
Either way, take into account the following things that could cause all that hard and expensive exterior painting work to fail:
- Wood was wet when it was painted. If only the surface of the wood is wet, then only 1 sunny day is usually needed for drying prior to painting. If the wood is saturated, several sunny or windy days are necessary for drying prior to painting.
- Unfinished siding was exposed to several weeks of sunlight before painting. Sunlight degrades the unfinished wood surface, thus it will never hold paint as well as fresh wood. If the unfinished wood was exposed more than 3 to 4 weeks, lightly sand or power wash the surface to remove the thin layer of degraded wood before applying paint.
- Wood was installed directly over foam or foil-faced insulation board. Water can travel in behind the siding of the house through various routes but has to travel out through the wood, pushing the paint off.
- House has no interior vapor barrier. The absence of an interior vapor barrier is related to the problems of high levels of humidity inside the house during the heating season and wood that was installed directly over foam or foil-faced insulation board.
- Wood siding is dirty. If the siding is dirty, the surface of the siding should be power washed or cleaned with detergent and a stiff bristle or brass brush and rinsed well. Never use steel or iron, which causes iron stain and may glaze the surface.
- Brown stains appear on the surface of the paint. Paint does not have to fall off to fail. Moisture traveling through wood pulls water-based extractives through the paint, leaving brown stains on the surface of the paint. If the wood is kept dry, the water-based extractives in the wood will not bleed through paint.
Read the entire report at www.fpl.fs.fed.us/documnts/finlines/knaeb95a.pdf.
Published with permission from RISMedia.