Exterior Paint – Proper Prep
DEAR TIM: My husband and I intend to paint our 85 year old Victorian house. The wood siding has peeled to bare wood in many places. What can we do to maximize the life span of this new paint job? Should we power wash the exterior or just use a hose? Do the new paints require a primer? What is the best type of paint to use on our older home? Nancy - Utica, NY
DEAR NANCY: It appears that you and I will be doing the same thing this summer. It is time to freshen up my 10 year old Victorian home. Even though we might both follow the same procedures and use the same paints, there is a very good chance that my paint job will outlast yours by 50 percent or more. The first thing you need to do is identify what might be the cause of the excessive peeling on your home.
Paint really dislikes wood. Wood siding and trim are like my son - on the move constantly. Water vapor and liquid water that enter and exit wood cause it to expand and contract. This movement breaks the bond between paint and the wood fibers. Look for possible sources of water that might be getting behind the paint film on your house. Excessive indoor humidity or attic moisture can easily pass through exterior walls and enter the untreated wood siding from behind. Gaps between windows and doors and the siding can allow rain water to enter the end grain of wood. Overflowing gutters, leaking down spouts or roof leaks can drench wood trim and siding.
All of these problems must be corrected before you paint. In addition, you are fighting a losing battle with the 85 year old paint on your home. Old houses were painted with oil based paints. These paints become more brittle with age. As the wood moves back and forth, the paint simply looses its grip. Even though you may scrape loose paint, a year or so later another spot on the siding may succumb to the forces of gravity and peel away. Fortunately I do not have oil based paint or primers on my 10 year old house.
Successful paint jobs are based in surface preparation. This is the most unglamorous part of a paint job. Paint can labels all say to apply paint to a clean, dry surface. Scrape all loose paint and wash your house. Clean your house the same way you clean yourself in the shower. Use soap and water and rub the skin of your house! I happen to prefer using a tile grout sponge with powdered detergents. Be sure to rinse the soap from the old paint. After you wash the house, I guarantee you that you will find additional places that need to be scraped. Look closely for these potential trouble spots. Be sure to fill all nail holes with spackling compound and caulk all gaps between the siding and trim boards.
Power washing does not always remove all of the dirt from your old paint. What, you don't believe me? Take your car to a self-clean car wash that uses power washers. Wash your car and let it dry. I guarantee you that you will be able to remove a thin film of remaining dirt with a white glove or sponge. That same film is left behind when you power wash a house.
Power washers used by rookies can also damage and erode wood siding and trim. They can also drive water deep into bare wood. If you paint before the wood dries, the paint will very likely blister and peel within months - sometimes days.
Water based acrylic primers are a must. Please read a more up-to-date article on primers for exterior use: Exterior Paint - Proper Primers and Cleaning a MUST! These special paints are formulated to stick to bare wood or previously painted wood. Primers also help seal bare wood so that the finish coat sheen is uniform. Be sure to use a primer made by the same company that makes the finish coat paint. The finish coat paint instructions will tell you which primers are compatible.
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Purchase water based 100 percent acrylic paint for your top coat. These paints have the greatest amount of long term flexibility. Remember, paints are simply colored glues. They stick best to surfaces that are squeaky clean and dry. The extra day or two spent hand washing your house could easily add 2 to 3 years of life to the paint job.
Please click the following link to read my latest findings on primers for bare wood. It contains more up-to-date advice that is different from this older column: Exterior Painting You should also read another column about the exact paint I use on my own home. Since I learn about new and exciting products each week, it is no wonder I come across great paints. Go read about: Urethane House Paint.