How to Prep for Painting a House

If you're lucky, all your house may need before repainting is a good, healthy bath. Wash it down with a hose, and go over stubborn dirt with a scrub brush and warm, soapy water. Or wash it down with a power washer. If you're not so lucky, then you just have to face the fact that a time-consuming and dirty job lies ahead of you. Do the job well, and your paint job will not only look better, but it will last for five to eight years on average.

Start by thoroughly examining the outside of the house or outbuilding -- not just the exterior walls but under the eaves, around windows and doors, and along the foundation. Look for split shingles and siding, popped nails, peeling or blistering paint, mildew, and rust stains. Once you've identified the areas that need attention, roll up your sleeves and make the repairs.

Remove small areas of defective paint with a wire brush and/or a wide-blade putty knife.
©2006 Publications International, Ltd.
Remove small areas of defective paint with a wire brush and/or a
wide-blade putty knife. Scrub under the laps of clapboard siding
and on downspouts and gutters.

Scraping

Use a wire brush and a wide-blade putty knife to remove small areas of defective paint. Scrub under the laps of clapboard siding as well as on downspouts and gutters. For speedier work on metal, a wire brush attachment on an electric drill will remove rust and paint with less effort. For more extensive paint removal, invest in a sharp pull scraper -- a tool with a replaceable blade that's capable of stripping old paint all the way down to bare wood with a single scrape. Hold the scraper so the blade is perpendicular to the wood, apply moderate to firm pressure, and drag it along the surface. Keep the blade flat against the wood so it doesn't gouge the surface.

Move an electric orbital sander up and down or back and forth to remove old paint and feather rough edges.
©2006 Publications International, Ltd.
Move an electric orbital sander up and down or back and forth to
remove old paint and feather rough edges.

Sanding

For smoothing the edges of scraped spots here and there, you can wrap a piece of sandpaper around a wood block. For larger areas, it's less tiring and more effective to use an electric orbital sander. Move it up and down or back and forth across the surface to remove old paint and smooth rough edges at the same time. Don't use an electric disc sander or a belt sander. Both can leave swirls or dips in the wood that will show through a new coat of paint.

Melting

For particularly heavy deposits of paint, heat may be more effective than muscle. One way to apply heat is with an electric paint remover, which is a device with a platelike heating element that "cooks" the paint and has a built-in scraper to pull it off. Wearing heavy gloves, hold the heating element against the surface until the paint sizzles. Pull the remover firmly over the surface. The attached scraper will pull off the cooked paint as you go.

Another way to remove old paint is with an electric paint remover.
©2006 Publications International, Ltd.
Another way to remove old paint is with an electric paint
remover -- a  device with a platelike heating element
that softens the paint and has a built-in scraper.

Liquid Paint Removers

Use liquid paint removers only as a last resort. They work well, but they're expensive, especially on big jobs. Also, they can slop onto perfectly good paint, giving you one more problem to deal with.

Priming

Once you have removed all the loose paint, you should apply an appropriate primer to some of the distressed areas, especially if your paint-removal system has exposed raw wood or bare metal. The kind of primer you use depends on the kind of paint you'll be using later. For latex paint, use latex primers; for solvent-thinned paints, use solvent-base primers; and for metals, use metal primers. Not only do these coatings provide extra protection against the elements, they also form a firm foundation for finishing paints. Also, priming is always required when you're working on new wood.

Other Prep Work

Even if you're fortunate enough to skip spot-scraping, sanding, and repriming, there are still some prepainting chores to attend to. They're much less laborious than removing peeling paint but no less vital to a successful job.

Rust stains on siding, overhangs, and foundations need to be removed. Leaks in gutters and downspouts have to be repaired. Loose caulking should be replaced, along with split shingles. Cracks in siding must be filled, sanded, and primed. Mildew must be scrubbed off, and steps should be taken to eliminate its return.

Also, to make painting easier, storm windows, screens, shutters, awnings, wall-mounted light fixtures (be sure to turn the power supply off), the mailbox, and even the street address numbers should be taken down, cleaned, and painted separately. You may even want to remove downspouts, as it's sometimes difficult to get a paintbrush behind them.

To make painting easier, remove light fixtures and other accessories.
©2006 Publications International, Ltd.
To make painting easier, remove light fixtures and other accessories.

You can typically complete all of these preparations for an entire house in a single day or over a weekend. If you're painting a porch or an outbuilding, it may only take an hour. If you're painting with latex, you can start the following day; solvent-base paint does not adhere well to moist surfaces so wait several days until all the washed surfaces are absolutely dry before applying this type of paint.

Washing

Not only will this process get the outside of your house clean and provide a dirt-free foundation for the new coating, it will also help you find surface flaws that have to be dealt with.

Depending on just how dirty the outside of your house is and on the house's size, there are two ways to approach this job. If you live in an average-size house, use a garden hose with a carwash brush attachment to bathe the big areas. For caked-on dirt, use a scrub brush or a sponge and a pail of warm water with a good, strong household detergent in it. Work from the top down, and rinse all areas where you scrubbed with water.

To remove caked-on dirt, use a scrub brush or a sponge.
©2006 Publications International, Ltd.
To remove caked-on dirt, use a scrub brush or a sponge and a pail of
warm water with a good, strong household detergent in it. Work from
the top down and rinse all areas where you scrubbed.

For bigger houses or for faster work on smaller ones, rent a high-pressure spray cleaner. This device attaches to your home's water-supply system and puts out a jet of water at a pressure of about 600 pounds per square inch. It is equipped with a handheld wand tipped with a trigger-activated nozzle. The pressure is high enough to dislodge not only stubborn dirt, mildew, stains, and dried-on sea-spray salt, it's enough to remove peeling paint. In fact, if the jet nozzle is held too close to the surface it can even peel off perfectly sound paint, split open shingles, and drill a hole in siding. So follow the manufacturer's directions and wear goggles and protective clothing.

You can use the spray cleaner while working from a ladder -- although scaffolding is better -- but practice at ground level first; the force of the spray against the house could knock you off a ladder if you're not careful. Some of these machines come with separate containers you can fill with cleaning solutions or anti-mildew solutions. Sprayers are so powerful that ordinarily you probably won't need to use a cleaning solution; if you do, remember to rinse the surface with clean water afterward.

Resetting Popped Nails

The house bath may reveal nails that have popped out of the siding or rusting nail heads that have left streaks of rust on exterior walls. If so, use sandpaper or steel wool to clean the nail heads. On clapboard siding, use a nail set to recess the nail head about ⅛ inch below the surface of the wood. Dab on a coat of rust-inhibiting primer (unless the nail is aluminum or nonrusting galvanized steel), and let it dry. Then fill the nail hole with spackle or putty. When the filler is dry, give it a coat of primer. For flathead nails, which cannot be recessed, sand the heads until they're shiny, and coat with primer.

Tie a rope around the trunk, and pull the tree away from the house.
©2006 Publications International, Ltd.
To keep trees out of the way while you're painting, tie a rope around
the trunk, and pull the tree out away from the house. Stake the
other end of the rope out in the yard.

Covering Shrubs

Trees, bushes, and ornamental shrubs can also get in the way of your painting. Prune any branches that hang over the house or brush up against walls. Evergreen trees and tall bushes growing close to the house can be wrapped with canvas drop cloths. Tie one end of a rope around the trunk at least halfway up. Pull the top of the tree out and away from the house, and tie the other end of the rope to a stake placed farther out in the yard. Cover smaller shrubs, flower beds, sidewalks, and driveways with drop cloths to protect them from paint drips and spills.

Estimating How Much Paint You'll Need

The size of the house, the condition of the surfaces, the type of coating you select, and the method of application are all factors that will determine the amount of paint you need to buy.

Narrow lap siding, shingles or shakes, masonry, or stucco exterior walls can take 10 to 50 percent more paint than smooth, flat walls.

Airless sprayers, which apply the equivalent of two coats of paint at one time, may require twice as much paint as brushes, rollers, or pads for the same surface dimensions.

You can get more standard, premixed paint if you run out. Or, if you buy too much, many stores will give credit or refunds for unopened gallons. With custom-colored paints, however, it may be difficult to get a precise match if you run short. Calculate your needs carefully, then buy an extra gallon for insurance.

To determine how much paint your house needs, measure the house's perimeter. Then multiply that figure by the height, excluding gable ends. Take the measurements with a steel tape measure, or reel out a ball of twine around the house and mark and measure the twine. If you will use a different paint on your home's trim, subtract 21 square feet for every door and 15 square feet for each typical window. Divide the final figure by the square-foot coverage specified on the can of paint to determine the number of gallons you will need for one coat.

If your house has gables, you can estimate by just adding 2 feet to the height when making your calculations. For more precision, measure the width of the gable wall and multiply that figure by its height. Divide the final figure by 2 to determine the gable's square-foot dimensions.

For trim paint, the rule of thumb is 1 gallon for every 6 gallons of wall paint. To be more accurate, you'll have to figure the areas of doors, windows, and shutters. For gutters, a linear foot is about equal to a square foot, so for 50 feet of gutter, buy sufficient paint to cover 50 square feet.


Now you're ready to start painting. Keep reading to learn about painting siding and trim.