How to Paint Your House (and why you may not want to paint your barn)

Enlarge Image Image Gallery For best exterior painting results, use acrylic latex paint and synthetic bristle brushes. ISTOCKPHOTO/NICOLETTE NEISH

Freshly painted outdoor wood is a beautiful thing. Too bad it doesn’t last. After five, 10 or 15 years of exposure, siding, trim and fences need a recharge — that’s just the way it is. But painting outdoor wood, especially an entire home, can be a high stakes game: Do it right and your efforts will endure two or three times longer than if you cut corners. That’s why a little extra know-how and effort is so worthwhile.

Beauty does matter, of course, and to understand the essentials behind a long-lasting outdoor paint job, you need to recognize the three forces that will work against you: sunshine, moisture and temperature fluctuations.

These are the archenemies of outdoor paint. Ultraviolet (UV) radiation breaks down surface paint layers, while seasonal expansion and contraction of underlying wood causes paint films to crack. Flaking, bubbling and peeling follows shortly behind as water sneaks in behind the paint, breaking its bond to the wood. Getting the most from an exterior paint depends on thwarting these three forces.

By the way, you may be surprised to learn that exterior paints and stains do not enhance the rot resistance of wood in any meaningful way. In fact, in some cases they can even trap moisture and promote rot. We’ve been conditioned to think otherwise in an effort to boost product sales. The fact is that exterior wood finishing is mostly about aesthetics. According to the University Extension office of Iowa State University, “The simplest and most economical way of finishing an exterior wood surface is to allow it to weather naturally. Wood exposed to the weather will undergo color changes during transition from the original to the final gray color.” For more on this, download Finishing Exterior Wood Surfaces. Got a new barn or outbuilding? Letting the surface weather naturally or painting only the trim is a viable option. Bare barns everywhere stand as testimony to the enduring qualities of unfinished exterior wood. (See photo in the Image Gallery.)

Prep before Painting

It’s often said that preparation is key to long paint life. But what exactly does this mean? Part of the confusion comes from the fact that effective prep for new wood is quite different from what is required for renewing a previously painted surface.

Are you repainting exterior wood? Take a look at “Dealing with Lead Paint” (below) before you settle on a preparation strategy. The presence of toxic lead in many older paints complicates the prep process on large jobs to the point where some folks decide to install new siding rather than repaint.

Every outdoor repainting job starts off best with a good pressure washing. If you find that some paint flakes or bubbles remain, brush them off with a heavy-duty wire wheel spinning on an angle grinder after the surface has dried. (See photo in the Image Gallery.) This regimen will probably leave some stubborn areas of old paint behind, but there’s still no better way to make an initial attack. Next, you need to make some decisions.