Exterior Paints

A coat of paint not only creates an attractive appearance for years to come, it also protects exterior surfaces from moisture, fading and temperature changes. A high-quality paint will provide better protection, complete coverage, easier application and longer-lasting results. When it comes to buying paint, you have lots of choices, some determined by your application and others that are based solely on your preference. Before you learn about all of the options available to you, use the following questions to focus in on the needs of your project:

• What types of exterior surfaces do you plan to paint?
• Are they chalky or layered with previous coats of oil paint?
• Are you painting bare wood, metal or concrete?
• Does the surface require frequent cleaning or have imperfections?
  
  

Quality, Types, Tips and Primer

High-quality paint is important for any project, but it’s especially important for exterior projects, which are subjected to harsh weather conditions day in and day out. Take some time to consider long-term benefits of better paints in addition to their initial cost. A good paint will require fewer coats and last longer, saving you money and time in the long run.

Water-Based vs. Oil-Based: In general, water-based paints are preferred for most exterior applications, but oil-based paints may perform better under certain conditions. Water-based paints are flexible enough to expand and contract with the siding on a house, they’re breathable, so they won’t trap moisture and crack or peel, and they dry significantly faster. Oil paints usually take between 8 and 24 hours to dry, while water-based paints dry in just 1 to 6 hours. Oil-based paints offer better adhesion and stain blocking, so they’re better for chalky surfaces, stained surfaces, bleeding woods (tannin or sap) and metals that rust.

• Water-based paint can be applied over oil-based paint, but oil-based paint shouldn’t be applied over water-based
• On surfaces with four or more coats of oil paint, stick with oil, since a water-based paint may cause the oil paint to pull away and crack
• Latex paints with an all-acrylic binder hold up to weather better than latex paints with a vinyl-acrylic binder

Paint Base	Description	Major Advantages
Oil-based (alkyd)	Consist of a pigment and resin in a solvent thinner. When thinners evaporate, the resins form a hard coating, leaving behind the pigment (which provides the color).	Better surface penetration Better adhesion Wearability Better flow and leveling Dries to a smoother finish with fewer brush/roller marks
Water-based (acrylic; latex)	Consist of a pigment and binder with water used as carrier.	Better gloss and color retention Breathable (won’t trap moisture) Quicker drying Less odor Nonflammable Soap and water cleanup Low VOCs (Volatile Organic Chemicals)

Primer: Bare wood and some other bare surfaces need to be primed before you paint them. Like paints, primers come in oil- and water-based varieties. Oil-based primers are suitable for use with oil- or water-based paints, so you could prime a chalky surface with oil-based primer for better adhesion and still take advantage of the benefits of latex paint. Water-based primer is not recommended for use under oil-based paint.

• Water-based primers are recommended for most applications, but oil-based primers are preferable for stained wood, bleeding wood (sap or tannin) and metals that rust
• Oil-based primers can be used with any paint, but water-based primer should only be used with water-based paint
• There are specific primers for wood, concrete and certain metals, such as galvanized steel, iron and aluminum
  
  

Paint Types: Unlike interior paint, exterior paint must withstand a variety of harsh external influences. For this reason, exterior paint is offered in several "specialty" formulas designed to meet the specific requirements of your substrate. Use this chart to select the paint that is appropriate for your outdoor painting project:

Paint Type	What You Should Know
Floor/Porch Paint	Oil and latex available; 100% acrylic latex lends the best results Provides weather-resistant coverage for garages, porches, decks and concrete surfaces
Gutter Paint	Oil and latex are both available; oil is better for tin gutters Adheres well to galvanized steel and aluminum A galvanized metal primer must be applied before painting
House/Siding Paint	Oil and latex formulations available Will withstand wear and exposure to severe weather conditions Manufacturers offer specific formulations for regional climates
Masonry Paints	Usually latex Ideal for stucco, concrete, cement and shingles Most require a special pretreatment or bonding primer
Pool and Marine Paint	Look for a polymerized cement-based product for concrete and gunite pools Look for paints that provide stain- and abrasion-resistance Be sure to check for compatibility with your surface (pool, concrete deck or spa)
Roof Paint	Look for an acrylic-latex blend Most are mildew- and algae-proof Should not be used for waterproofing or to repair roof leaks Can be tinted to match roof color

Surface Preparation: Even the best paints won’t adhere well or produce good results if you don’t prepare the surface correctly. If the surface has been painted, check for peeling paint and scrape it off prior to applying a new coat. Whether or not the surface has been painted previously, it needs to be clean. If unpainted wood is gray or weathered, it should be sanded.

• Clean, scrape and fill holes in the surface prior to paint application
• Sleek surfaces may require light sanding to improve adhesion with primer or paint
• Prime all bare wood, including bare spots and nails on previously painted surfaces
  
  

Weather: Just like proper surface preparation, applying paint in the right weather can make or break a project. In temperatures colder than 50˚F most paint won’t dry, but cold-weather paints are available for cooler climates. In direct sunlight paint may dry too fast, causing lap marks. Wind can also cause paint to dry too quickly, in addition to blowing dirt onto the surface.

• Direct sun and wind can cause paint to dry too fast, especially fast-drying latex paints
• Cold temperatures, rain and humidity can prevent paint from drying properly
• Check the label for recommendations on temperature ranges before starting
  
  

Features

Flat/Matte Finish: A flat finish hides imperfections better than a glossier finish but doesn’t clean as well. Flat finishes are generally used for siding.

Glossy Finish: Glossier paints create a hard, shiny, durable finish that’s easy to clean. Glossy paints bring out details, so they’re usually preferred for trim and doors. They also accentuate imperfections, so they’re not well suited for siding or walls.

Satin Finish: A satin finish has a slight gloss, so it’s more cleanable than flat paint yet still hides imperfections well.