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2 posts from March 2011

Monday, March 28, 2011

Advice from the Pros:

Spring Exterior Diagnostics Part Two

It's very likely that the exterior inspection recommended in our last post will turn up some problems here and there. The good news is that paint problems are usually easy to fix if you can figure out what caused them in the first place. Here are a few of the more typical problems and their likely causes; in our next post, we'll tell you how to fix them. First you should identify if the problem is localized or general. If the problem is limited to a small area or on one side of the house it should be easy to identify and correct. If the problem exists on the entire house it may be a much larger issue and you should probably have a paint expert to inspect your home. Consult your local Benjamin Moore retailer to find an expert who can help.

Small or medium-sized blisters are a sign of moisture trapped beneath the finish and can result from several conditions:

Blistering Paint

  • If wood--or any substrate--was wet when it was painted, moisture will be trapped under the paint film. If only the surface was wet, a dry sunny day is usually all that's needed to dry it out. But if the wood was saturated--from pressure-washing, for example--several dry, low-humidity days with lots of wind will be needed before you can paint. (Pros look for substrate moisture contents between 12 to 14%--if they're unsure about conditions, they'll test with a moisture meter.)
  • If the substrate was too hot when paint was applied, it may dry too quickly, trapping solvent vapors which can then turn into blisters. To prevent this, professionals avoid painting when the surface temperature is above 90-degrees F and don't paint in direct sunlight.
  • High humidity can also cause blistering. When water-based paints cure, the water should evaporate as fast as or faster than the solvents. In humid conditions, water cannot evaporate and the solvents end up evaporating first, causing the paint to cure while still in a water-filled state. Oil-based paints, having a slower drying rate, are especially susceptible to solvent entrapment.
  • When a house is poorly air-sealed and poorly ventilated or if the walls are missing a proper vapor barrier, water vapor inside the house tends to escape through the walls. Instead of being trapped by the wood siding, water vapor passes through and starts to push the paint off, resulting in blistering.


  • If interior moisture is excessive, such as in unventilated baths and laundry rooms, for example, peeling will occur on the exterior siding. Don't try to repair and repaint before correcting this problem.
  • If unfinished siding is exposed to several weeks of sunlight before painting, UV will degrade the wood and it will not hold paint well.
  • Peeling will occur if there's reduced adhesion because of dirt on the substrate or because of mill glaze, caused when the surface of newly-milled wood is hardened by dull planer blades, or when resins in the wood are drawn to the surface during the milling.
  • Paint can begin to crack and peel from paint build up. Older homes that were painted multiple times with oil based paint exhibit this problem. 

Peeling Paint

Paint does not have to fall off to fail. Woods such as redwood or cedar contain tannins that bleed out of the wood when they come in contact with moisture. If these wood species are not properly primed with a product specifically designed to block tannin bleed, this discoloration may end up coming through your finish coat.

Tannin Staining Paint

Wood that stays wet for an extended period of time eventually rots. If you find wood that is soft and spongy, it has degraded to the point that it will never hold paint, and should be replaced.

Of course, not everything you uncover in your inspection is cause for concern: Expect to find some chalking or fading of the finish--both are a natural consequence of aging. Excessive chalking is probably a sign that you'll have to repaint in the not-too-distant future. Dark patches of mildew are also likely, especially in shady or damp areas, and are unsightly rather than indications of anything more serious. Washing or scrubbing with Benjamin Moore's Clean (product number 318) or a solution of 1 part bleach to 3 parts water should remove them.

Thursday, March 17, 2011

Advice from the Pros:

A Spring-time Walk That Can Save You Dollars


Here in the Northeast--and in most of the rest of the country--it's been a hard winter. Fortunately, spring is just around the corner, and once the snow melts it's a great time to assess the toll winter has taken on your home. Simply taking a ten-minute stroll around the outside and examining the foundation, siding, trim, porch, and deck can tell you a lot and maybe head off any problems before they become more costly fixes down the road:

In the spring there's usually still a lot of moisture in the ground, making it easier to see if you have drainage problems around the foundation. Look for water pooling up against foundation walls on the outside, and obvious signs of leakage inside. Besides actual cracks in the concrete, evidence of moisture problems include peeling or flaking paint, efflorescence (or salt deposits), chalky residue, and mildew.


Efflorescence on masonry--probably a sign of excess moisture.

Soil often settles around a foundation, so adding more soil and re-grading so that water flows away from the house--rather than toward--is a simple fix. Hundreds of gallons of water fall on your roof during a typical rainstorm and repairing missing or broken gutters and downspouts will divert this deluge away from the house.

Decks and Porches
Decks really take a beating from freeze/thaw cycles. Water that seeps into cracks in wood will freeze and expand, swelling the substrate and stressing the finish coating. Cracked and peeling finishes indicate that there's a problem, but also look for excessively-cupped or bowed boards and rust stains from screws and nails. To prevent minor problems from becoming major ones, decks should be cleaned annually and recoated every one or two years.

All painted finishes eventually break down from exposure to sun and rain. But if paint has been applied to a properly-prepared substrate under suitable environmental conditions, it should last several years. If you're not getting good performance, the kind of failure can tell you about what caused the problem--and what you can do to correct it. Chalking and fading are normal signs of aging paint, for example, particularly on the south side of a house where UV exposure is greatest. But if there are blisters or peeling paint, it's likely that there's a moisture problem of some sort. This can be caused by leaking or broken gutters, but it can also result from moisture trapped behind the siding. If you have stucco siding, look for efflorescence and cracks, as well as flaking or peeling paint. If you have wood clapboards or shingles, check for rot, particularly down near the ground and where the siding meets trim.


Peeling on wood siding--generally an indication of
moisture seeping to the surface.

Take a look at your landscaping, too: shrubs make decorative foundation plantings but they can limit air movement and prevent your siding from drying out. Prune back branches that are in contact with the house or move overgrown shrubs once the ground is workable.

Finally, take a close look at your doors and windows. Older windows may have loose glazing compound that should be replaced. Wood window sashes might look weathered, but often just need to be scraped, sanded, primed and repainted to look as good as new. Vinyl- or aluminum-clad windows and doors may just need a good cleaning.

It's amazing what a ten-minute inspection can reveal. That and a little preventive maintenance will minimize seasonal damage and premature paint failure, saving you money and headaches in the long run.

In the next post, we'll tell you what you need to do to prep your house for paint.