Open gutter guards are those where water enters the gutter through small holes in the top that filter out debris. While leaves may accumulate on top of the screenlike panels, manufacturers say that wind and rain will eventually wash them off.
Such gutter screening, which costs anywhere from 30 cents to several dollars a foot, is often sold in three- to four-foot-long panels at home improvement stores. The screening is made of vinyl, aluminum or another metal. Some varieties have large circular or diamond-shaped holes; others have a finer mesh.
Panels must be rigid enough to avoid sagging under the weight of wet leaves. The panels must also be anchored sufficiently that it won't blow away in the wind.
Closed gutter protection systems such as Gutter Helmet, GutterTopper and LeafGuard have solid tops. Often professionally installed, closed systems can range from $8 to $20 or more a foot.
Closed gutter guards are designed on the principle of surface tension, also called liquid adhesion. Rainwater adheres to the guard's surface as it flows over a curved "nose" into a narrow slot, while leaves and debris continue over the edge to the ground. If any small particles follow the water into the gutter, manufacturers say, they will just flow on out the downspout.
To visualize how surface tension works, hold a glass horizontally underneath your kitchen faucet. Regardless of the rate of flow, water clings to the glass until it gets underneath the curvature. On your gutters, water would curve over the nose of the gutter guard and be deposited into the gutter's channel.
However, Tim Carter, author of the nationally syndicated newspaper column Ask the Builder, tested a closed system at a home show by dropping small pieces of paper, simulating leaves, on the top. "The gutter cover deflected the large 'leaves,' " he wrote. "However, my small 'leaves' were sucked into the gutter."
Several factors beyond the sales pitches should influence your choice of a gutter protection system. No one system is right for every situation.
• Do you have trees on your property? If your home is out in the open, then gutter protectors are not critical, although Krilis cautions that even stray tennis balls or dead birds have been known to clog downspouts. While installing new gutters on 200 feet of roof line unsheltered by trees in McLean, Krilis's crew retrieved a full bag of debris that had accumulated in the old ones over the years.
• What kind of trees are on your property? No pine trees? You still may have a problem. Carter said, "Over time, all deciduous trees drop debris . . . and it becomes like a paste. It takes no time at all for [small] openings to get clogged."
• Are your gutters in good shape? It doesn't make sense to put new guards over gutters that are sagging or leaking. Nor does it make sense to pull down perfectly good gutters to put up an all-in-one system.
• Roof design is a factor. The roof's surface area and steepness, whether there are valleys where two parts of the roof join, or whether there are several levels of roofing that feed into the same downspouts, should all be considered in choosing a gutter protection system. Rich Cutaio, branch manager of LeafGuard of Maryland, said that systems that depend upon water flow over a solid top, such as his company's product, are not suitable for flat-roofed buildings.
• Consider the roof's exposure. A gutter system with northern exposure sheltered by heavy tree growth may be prone to algae or moss buildup, which could either thwart the water adhesion required for closed systems to work properly or clog up holes in open systems.
• Will the installer's or manufacturer's warranty cover necessary cleaning? Many systems are permanently attached to the gutters and roof, making it very difficult for homeowners to clean out debris. The gutter covers that hid my pine needle stash so well were anchored with what are now rusty screws that were almost impossible to remove.
