House siding is usually protected with flat paint, and trim with glossy enamel. Wood shingles and shakes can be painted, stained or protected with a clear finish. This suggests types of coatings suitable for various exterior surfaces. Ask your paint dealer about additives. Houses that are heavily shaded often have mildew problems. You can have a fungus-inhibiting additive mixed into the paint. Many exterior oil-based paints are designed to be self-cleaning. They gradually chalk or give off a powdery white substance that rain washes away.
Paint vs. Stain
Paint is a film-forming finish, which means it lasts longer, offers better protection and has stronger colors than stain. But paint films, especially dark colors, which can blister in the hot sun, are more likely to peel. Along with the dirt and grime that cling to it. This process keeps paint looking fresh but can stain red brick walls or dark siding located below. Latex paints are easy to apply, dry quickly, and clean up with water. They resist the alkali found in concrete and masonry that disintegrate alkyd paints; they are permeable to moisture, so they blister less and allow dampness to escape. Oil-based paints and stains take longer to dry and require hazardous sol-vents for cleanup, but some argue they go on smoother, dry harder and can be applied at lower temperatures. Stain is a non-film forming finish. The advantage to this is that it soaks into the wood, won’t peel and is easier to renew. However, stain colors are more muted, and they won’t protect as well as paint.
How Much Paint?
To estimate paint for a project, add up the length of all walls and multiply by the height of the building. Don’t subtract for windows and doors unless there are multiple large units. As a rule of thumb, 4 liter of paint will cover:
- 33 sqm of previously painted wood siding.
- 19 sqm of rough sawn wood siding or shakes.
- 9 sqm of raw stucco or brick. In normal situations, you’ll need one unit of trim paint for every six units of siding paint.
Cement based siding Concrete block Aluminum siding Vinyl siding Porch floors Stucco and brick No need to prime if existing paint is in good condition. Lightly sand to remove gloss and aid adhesion. Spot prime bare areas. Coat with latex, or oil-based paint once surface is clean and dry. Prime bare areas. Coat with high-gloss, oil or latex based enamel paint.
If applying paint, prime beforehand with a stain-blocking primer, or knots will bleed through topcoat. Solid body and transparent stains and clear finishes require no priming. Most new hardboard siding has factory-applied primer. Usually comes with factory applied primer. If not, use alkali-resistant primer. Topcoat with 100-percent acrylic latex paint. Latex or special concrete primer. Use “block filler”-type primer to fill pores and voids. Topcoat with latex paint.
Pressure wash to clean and remove any chalking. Apply 100% acrylic exterior paint once siding is clean and dry. Apply latex house paint once siding is clean and dry. Do not paint darker than the color of the original siding in order to minimize expansion and contraction problems.
Apply oil based primer. Topcoat with special porch and floor paints. Nonskid additives available. Some treated-wood floor manufacturers suggest not priming. These materials are basically maintenance free; once you start painting them, you’ll need to keep painting them so think twice please. Use flat latex paint on clean, dry surfaces. Wash thoroughly. Apply primer formulated for use over metal. Topcoat with latex paint.