The water-based formulation of latex paints makes them easier to clean, less expensive, and faster drying than alkyds. In addition, latex paint dries to a porous finish, allowing moisture in wood to evaporate through the paint film, which prevents peeling.

Latex paints are not all the same. Although the first latex paints were named after their synthetic “latex” rubber base, synthetic rubber isn’t used anymore. Now the term “latex” encompasses all water-borne paint. But within that category, you have choices: vinyl-acrylic, all-acrylic, and alkyd-modified latex.

Vinyl-acrylic latex is the least expensive, but it’s suitable for shorter-durability exterior walls. High-quality exterior paints are either all-acrylic or alkyd-modified latex. Both are excellent. But if the siding was previously painted with an alkyd or is chalking, you may want to consider using an alkyd- modified latex because it does a better job of penetrating and anchoring the coating on a chalky surface.

Top-quality latex paints made with 100% acrylic binder last at least twice as long as ordinary housepaint: up to 10 years or more versus a lifespan of only three or four years with ordinary exterior paint.

The cost of the longer-lasting coating? Only $8 to $10 more per gallon. And because it takes only about 20 gallons to apply two coats of paint on an average-size house, the added cost of a top- quality product is just $160 to $200.

More to the point, the great majority of the cost of repainting, typically more than 90%, goes for labor. As a result, it’s important to paint with a coating that lasts as long as possible.