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A fresh coat of exterior paint can transform even the most run-down “fixer-upper” into a stylish “classic,” dramatically boosting curb appeal and adding thousands of dollars to your home’s resale value. Even if you’re not trying to sell your house, a professional-grade exterior paint job can protect it from the elements — wind, rain, mold and mildew — or at the very least, make your neighbors jealous.

Let’s not delude ourselves, though. Painting over the outside of your home can be a huge investment of both time and money. Paying a professional can run into the tens of thousands of dollars. You can do it yourself for a fraction of that cost, but prepare to spend long days on high ladders scraping away at stubborn paint and inhaling primer fumes.

If you’re up to the DIY challenge though, we’ve assembled 10 essential tricks for making your house-painting project go smoothly and look great. With any luck, it will last 25 years, at which point it’s the next owner’s problem.

Let’s start with an unusual painting consideration: the calendar.

10. Check the Weather

Moisture is a painter’s worst enemy. Waterlogged wood siding or concrete foundations will cause paint to bubble and crack only months after a fresh application. Save yourself the frustration (and cost) of repainting by waiting until all surfaces are moisture-free.

If you live in a region with long, snowy winters and wet springs, wait until at least June before starting an exterior paint project. If you live in a hot and humid region, plan on the cooler, drier weather of fall. Professional painters carry moisture meters and won’t lay a brush on a piece of wood with moisture content higher than 12 percent.

You can buy a meter for as little as $20 — or just keep tabs on the weather. Wait until the forecast calls for clear skies and warm nights for at least the next week. Rain can wash away fresh latex paint, and temperatures below 50 degrees Fahrenheit (10 degrees Celsius) can make it harder for paint to adhere to the surface and cure properly.

9. Look Out for Lead

The first step in an exterior painting project is to remove all cracked, bubbling and otherwise nasty old paint. If your house was built before 1978, there’s a very good chance that at least one of its many paint layers contains lead, a known neurotoxin that can seriously impair brain function and development, especially in children.

To test your paint for lead, consult this list of EPA-approved labs and call the nearest one to find out how to mail in a sample. If it comes back positive, you’ll need to take special precautions when scraping off the old, damaged paint. The best solution is to rent a product called the PaintShaver— a motorized grinder that quickly strips paint from wood surfaces and sucks the dust and debris directly into a sealed vacuum bag.

Even if you aren’t dealing with lead paint, you’ll still want to minimize mess and avoid inhaling paint dust. Buy yourself a nice painting respirator so you can breathe easy. Then invest in some canvas drop cloths like the pros use. Unlike the cheap plastic versions, they don’t rip and you can reuse them over and over. Lay the drop cloths below your work area and drape them over shrubs and other landscaping to protect landscaping from falling paint chips.

8. Patch Those Cracks

Painting the exterior of your house can be a painstakingly slow process, but it gives you an opportunity to inspect your home up close. While you’re scraping away at the trim for hours, pay attention to the state of wood clapboards, window ledges and shutters. If you find any broken, cracked or rotted sections, fix them now so they won’t come back to haunt you later.

If a piece of wood is rotted through, it needs to be removed and replaced. But if there are just a few cracks or holes, patch them using a professional-grade exterior patching compound. No mixing is necessary; just spackle the malleable putty right into the problem area; smooth it in the opposite direction, let it dry, and then sand the surface smooth. Rough sanding the edges of the hole itself will help the compound to adhere.

To ensure a perfectly smooth finish, consider sanding down all wood surfaces. We know it’s a huge pain, but at least you can rent or borrow a power sander to cover more surface area in less time. Pay particular attention to the places where bare wood meets existing paint. Use a fine 50- or 80-grit paper to really make those transitions seamless.

7. Give It a Bath

Remember when we told you that it’s critically important to paint on a moisture-free surface? Forget that for a second. Once you’ve stripped off old paint and patched up busted siding, you need to attack another unsightly plague of old houses: mold and mildew. And the best way to do that is with an old-fashioned scrub and rinse.

Mold, mildew and other fungi can embed themselves deep in wood fibers far beyond the reach of a scraper or sander. The best weapon is to mix up a diluted solution of 1 cup (236 milliliters) each of bleach and trisodium phosphate to 2 gallons (7.5 liters) of water. Use a spray bottle to spritz problem areas and scrub deeply with a stiff-bristled brush.

Let the bleach solution do its work for a few hours before giving the entire house a gentle rinse to remove dust and paint debris. It’s tempting to use a power washer, but that convenience can come at a price — high-powered streams of water can gouge softer woods. When in doubt, try a regular garden hose.

OK, now you can remember our moisture advice. Wait a few sunny days after rinsing before proceeding with the painting project.

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