Climate is another factor to consider. Sunlight, wind, rain and salty weather can all wear out exterior paint. Oil-based paint is durable against wind, rain and temperature changes, but sunlight tends to degrade it. Alkyd paint chalks and sheds very thin layers when it begins to wear. Latex paint is the more durable option for very sun-drenched and relatively dry climate areas. Latex paint with high vinyl content should be avoided, however. Acrylic resin is by far the more durable binder for outdoor latex paint. Westminster Home Painting
When the primer is dry, caulk all small joints (less than ¼-inch-wide) in the siding and trim. Most pros use siliconized acrylics—paint won't stick to straight silicones—but Guertin and O'Neil like the new, more expensive urethane acrylics for their greater flexibility and longevity. O'Neil stresses that it's shortsighted to skimp on caulk. "If the joint fails, you're back to square one." Guertin uses the lifetime rating as his quality guide. "I don't expect 35-year caulk will last 35 years, but it should last longer than a 15-year caulk." Westminster House Painting