Seattle Exterior Painting
The type of siding and windows you have on your home and the year your house was built will determine the proper preparation procedures and application methods.
Most modern exterior super acrylics are best applied by airless spray to manufacturer recommended mill thickness. Once the substrate and surface is completely sealed with primer and sealants, the goal is to transfer the contents of the can to the surface with as little disturbance to the resin as possible. As an example: Sherwin Williams has a great exterior paint called “Duration”. This is a lifetime coating if applied under the proper conditions and to exact specifications and applies at a thickness of 7.0 mils wet. This mil thickens can not be achieved by brush without making a mess.
We completely Mask off areas that are not scheduled for paint. We place masking tape along the edge of house trim, and around window and door frames and trim, since this is likely to be painted in a different color. We use masking over windows and doors, including sliding glass doors, to protect them from drips.We Place plastic drop cloths over plants and shrubs, or where paint may drip on porches, roof sections, sidewalks, driveways or any other surfaces.
Old House Restoration
Old houses built in the 20’s 30’s and 40’s typically have old growth cedar clapboards. The single biggest issue with the coating longevity on this substrate and this particular type of construction, is moisture. Thermal exchanges cause water vapor to seep through the walls and the issue is compounded by inadequate venting and vapor barriers. This moisture eventually finds its way thru the wood fibers starting on the backside of the siding, and then the first layer of old, stiff ,oil based paint. The old coatings pop off where the bond is the weakest. The visual evidence of this is the bubbles on the surface which soon crack open leaving an unsightly void where external moisture can intrude on to the surface and begins the degradation and rotting process.
The best way to avoid future peeling issues is to address the underlying moisture problems. The new coatings will; however, withstand more moisture if applied properly and applied to the newly exposed cedar.
The most important part of this preparation process is to remove as much of the old coatings as possible. This includes ares of the house where the paint looks to be in O.K shape but is surrounded by areas of failures.
We use different methods to get all the old layers of paint off the siding. When we are satisfied enough of the old paint layers have been removed we will prepare the cedar so that is clean and dry, sufficiently abraded for maximum product absorption and we ensure all nails are set and sharp edges smoothed.
We then use a penetrating oil primer to condition the surface and brush this product into the grain. We also prime on top of this conditioning coat with an acrylic product primer that has good breathability and elasticity. This product is also applied by brush to ensure all fissures and knotholes are filled with product.
We will also seal all cracks and gaps with an elastomeric urethane caulking compound which will form a nice tight elastic seal around windows and doors and other possible entry points for moisture intrusion.
Many people are led to believe that a high PSI pressure washer is all that is needed to prepare the exterior of their home for painting. Pressure washers can be a good tool if used properly to remove dirt and grime and surface salts accumulated on the surface. If used incorrectly a high powered pressure washer can cause more damage to the wood and problems with water blasting into areas where it gets trapped and evaporates over the following months in the form of water vapor and cause more paint failures down the road. We use a pressure washer very carefully to gently remove the surface contamination in addition to other cleaning methods: like a good ol sponge and water!
Exterior Mildew Removal
Mold and mildew are almost always prevalent somewhere around the exterior of a home in the pacific northwest and especially if older than 5-10 years. This needs to be completely removed before any paint application. mildew is usually only a surface problem and typically occurs on siding, decks, patios, roofing materials, stucco, driveways and even concrete. Normally it does not affect the strength or other important properties of the exterior surfaces. It just looks bad. In some cases major mold infestations on painted surfaces may extend through the painted surface and into the substrate in which case we remove it and sand smooth. Although there are test kits that will determine if you have mildew, we usually assume it is and use the appropriate removal methods.
In many instances we can use a simple bleach and water solution and pressure washing to remove the effected areas. Some types of mildew require a bleach activator like Jomax that will keep surrounding plants,flowers and shrubbery safe from any adverse affects. In other instances we will use a TSP solution. Keeping mold and mildew from coming back will require the use of products which have a high concentration of mildew inhibiting agents. Oil based products are more susceptible to microorganism growth as are lower grade paints which commonly extended with thickeners, which can feed mildew.
Most high end exterior paints are formulated with mildewcides to make the paint film mildew resistant. Mildew inhibitors such as the biocide barium metaborate prevent the formation of new mildew.
We use Paints with a higher concentration of zinc oxide which is used for pigment, this aids in mildew prevention more than paint containing titanium dioxide. Paints or primer containing linseed oil are highly susceptible to mildew as are lower grade paints commonly extended with thickeners, which can feed mildew.
We also recommend against using flat paints on exterior surfaces because they have a more porous surface. Mold and mildew spores will grow much easier in these porosities. We like to use Eggshell, low luster or satin coatings that are less porous so mold spores have fewer surfaces to grab on to.