Latex Easy cleanup, durability, and fast drying make latex the choice for amateurs; can be applied even over damp surfaces; naturally mildew-proof; may be incompatible with a previous oil-based finish. Don't thin; apply with one stroke of the brush or roller; work it out too far and you'll get thin spots. Acrylic Actually a type of latex; a water-thinned paint that dries even faster than most and will cover just about any building material, including masonry and properly primed metal. About the same as ordinary latex. Alkyd Solvent-thinned, synthetic-resin paint; has most of the same properties as oil-based types, but dries more rapidly; good over old oil- or alkyd-based coatings; excellent hiding power. Thicker consistency makes alkyd more tiring to apply, but it levels better than latex. Oil Slow drying times (12 to 48 hours), strong odors, and messy cleanup; some professionals still swear by its durability. Lengthy drying time makes bugs and rain real perils. Primers Seal new wood and metal with a recommended primer; generally, one coat of primer and one of finish is more durable than two finish coats; finish not to be used as primer or vice versa. Priming usually is easier than finishing, but porous surfaces can soak up a lot of paint. Stains Solvent- or water-thinned types provide transparent, semitransparent, and solid finishes for natural wood siding and trim; some include preservatives or offer a weathered look. Brush, roll, or spray on almost any way you like.
Porch and deck Choices include epoxy, alkyd, latex, polyurethane, and rubber-based; most work on wood or concrete floors and dry quickly; surface preparation varies; colors limited. With most, you just pour on the floor, then work out with a long-handled roller or wax applicator. Metal Solvent- or water-thinned types in a wide variety of colors; include rust-resisting priming ingredients so you needn't worry about small bare spots; all-bare metal should be primed separately. Brush, roll, or spray on for a broad range of finish effects. Marine Formulated for boats; provide a super-durable finish on wood and some metal trim; expensive, so not for big areas. A gooey consistency makes them difficult to apply. Masonry Include latex, epoxy, Portland cement, rubber, and alkyd; some serve as own primers; seal masonry with clear silicone. Latex is easy to apply; other types can be a lot of work.
The following characteristics vary among different types of paint, and can have a big impact on the success of your project.
Drying time and durability. Paints with oil and alkyd bases dry slowly, making them susceptible during application to insects and sudden rainstorms. Once they set up, however, they are exceptionally durable. Latex paints are easier to work with, dry quickly, and have a porous, "breathing" quality that minimizes most moisture problems. They do have a tendency to peel, however, if applied over an improperly prepared oil- or alkyd-based finish, especially if it's a "chalking-type" latex paint.
Chalking refers to a self-cleaning quality formulated into many of today's exterior paints. They shed dirt by gradually eroding with each rainfall. Usually, you can see the "chalk" on foundation walls, shrubbery, and your coat sleeve, if you brush against a painted surface.
Previous coats. Once wood has been covered with a water- or solvent-thinned product, it's best not to change types when you apply subsequent coats. It can be done, of course, but you may run into problems. If you're not sure what type of paint was used before, you'll probably be safest to use an alkyd-based paint.
Luster. In addition to deciding what type of paint you want, you also must specify the luster -- flat, semigloss, or gloss. (The word enamel often is used instead of semigloss or gloss.) Most people prefer a flat finish for large exterior expanses, and reserve semigloss and gloss for areas subject to hard use or for trim.
Time spent painting. If you plan to match or approximate the present color, any paint will cover in one coat. However, products sold with a one-coat guarantee are thicker, with more resins and pigments. Most guarantees specify that the paint must be applied over sound existing surfaces or primed new wood. You will pay more for a one-coat paint, but the extra money spent might pay off handsomely, especially in terms of time saved.
Prices for a gallon of exterior house paint begin approxmately where interior wall paints leave off, for two main reasons. First, they contain more resin so that they are more durable and highly moisture-resistant. Second, most also have more pigment, the ingredient that gives paint its color.
According to most paint pros, you get what you pay for in exterior paint.
If you paint new or sanded wood, apply a primer. Latex primer is $8 to $16 per gallon. Alkyd primer is in the same ballpark - $8 to $22. At $19 to $26 per gallon, oil based primers are the most expensive.
Latex paint is $11 to $36 per gallon. Alkyd is cheaper: $8 to $22. Oil paints are: $19 to $32 per gallon. You can expect to pay more to mix custom colors.
How much paint you need depends upon the type and condition of the surfaces you'll be covering, the method of application, and the paint itself. Conditions vary considerably, so your best bet is to read the manufacturer's coverage figures, then expect to get slightly less.
To compute surface area, measure from the foundation to the eaves and multiply by the distance around the house. (Refer to Illustration 1 for help visualizing where you need to measure.) For each gable end, measure the distance from eaves to the peak, measure the width of the wall, and multiply the two. Then, divide the result by two.
If your home has narrow lap siding, add another 10 percent to your estimate. For textured materials, such as shingles or shakes, add 20 percent. Masonry and stucco -- both porous surfaces that soak up lots of paint -- can take up to 50 percent more.
If you buy premixed paint, you can always get more, and most stores will let you return unopened cans. Custom colors can be hard to match. So, buy an extra gallon; you can use the overage for various touch-up projects.