Why do my gutter guards keep clogging?

Gutter guards usually clog for one of four reasons: debris sits on top where wind cannot clear it, the guard is installed too flat or with a gap at the front, sap, moss or other growth builds up on the mesh or debris gets in underneath, or the downspout and gutter cannot carry the water away. Find where the water spills first; the spot usually tells you which.

Debris that never blows off

Guards rely on wind and rain to clear leaves off the top, and some parts of a roof get little of either. Look first for debris that has not blown off, particularly where two sections of roof come together, the valleys, or in areas that are protected from wind.^[1][2]

The slope matters here. Gutterglove's installation guide says the ideal slope of its guard is between 5 and 25 degrees,^[1] dropping it to between 5 and 10 degrees on a steeply pitched roof or a gutter hung low.^[1] A guard pushed down flat, or one that has sagged over time, holds leaves instead of shedding them.

Hood-style and curved guards have their own version of this. Amerimax's instructions describe debris accumulating behind curved, hinged guards, and the hinge flipping up so the gutter clogs.^[3]

What builds up on and under the guard

Some of what lands on a guard does not blow or wash off. The conditions that void Gutterglove's warranty include "Tree sapping on mesh; Insect/bird droppings on mesh" and "Mildew accumulation; Paint overspray; Moss accumulation,"^[1][2] and under that warranty it is the owner's responsibility to unclog the mesh.^[1] A gentle brushing from the ground is the usual first step.

Debris can also get in underneath, through an open seam between sections or an uncapped gutter end. Amerimax has the end of its metal guard bent down to form an end cap, which it says helps prevent birds and other animals from nesting in the gutter.^[3] On a single-storey eave, where the guard is screwed or clipped to the gutter rather than slid under the shingles, lifting one section near a downspout shows you what has collected inside.

Water that goes over instead of in

Overflow is not always a clog. Gutterglove's guide says the front frame of the guard should sit flat against the gutter's front lip, and the mesh trough should be at least 1/8 inch below the lip.^[1] When there is a gap, or the trough rides high, water skates over the guard and off the front, especially in a downpour.

Roof valleys and upper roofs are the other usual cause. If overflow is concentrated below a valley even after cleaning, Gutterglove suggests a rainwater diverter, a perforated aluminum piece that attaches at the end of the valley above the mesh and spreads the water over a wider area.^[1] Amerimax notes that a splash guard may be needed at inside and outside corners and where a downspout from an upper roof empties onto a lower roof,^[4] and suggests connecting the upper roof's downspout into the lower roof's gutter.^[4] The diverter attaches to the end of the roof valley, so fitting one is work on the roof,^[1] and so is rerouting an upper-roof downspout. Both are jobs for a pro.

The outlet and the gutter itself

A guard over the gutter does not stop a strainer at the outlet from filling up. Screens require regular cleaning to avoid clogging the downspouts,^[5] which is why flap valves are preferred over screens at the bottom of a downspout.^[5] Basket strainers like the one above need the same attention.

If the gutters spill during an ordinary rain with the guards brushed off and the gutter clean, the guards are not the problem. Clean gutters that still spill in ordinary rain point to a sizing problem: "A spillover of runoff is an indication of undersized gutter system."^[6] Wider gutters or an extra downspout fix that; guards cannot. See why gutters overflow.

Winter adds one more cause. Gutterglove warns, "Icicles can form, and ice can form on top of Atlas Gutter Guard in extreme cold weather where snow is present."^[1] Water that spills only in freezing weather is an ice issue, not a debris one.

How to find which one you have

Start from the ground in a steady rain. Overflow along a whole run points to fit, slope or undersized gutters. Overflow at one stretch points to a valley, a corner or a local clog. Afterwards, look for streaks or watermarks on the outside of the gutters and erosion along the drip line.^[6]

For anything you check from a ladder, stay on single-storey eaves and keep to the basics: the top two rungs of a straight or extension ladder are not for standing on.^[7] If you need to lift a section of a guard that is not under the shingles, Gutterglove's guide has screwed guards backed out and refitted through the same holes. For a taped guard, it says to cut the tape with a sharp knife and reinstall with screws.^[1]

Once it is clear, keep it that way with a simple maintenance routine.

Stop and call a pro if

• The clog or overflow is on a second-storey gutter, or the only way to reach it is from the roof.
• The guards slide under the shingles and you would have to lift roofing to free them.
• The gutter sags, has pulled away from the fascia, or the fascia behind it is soft.
• A ladder position would bring you near the service wire or any overhead line. A metal ladder must not be used when working on or near electrical wires.^[7]
• The fix is a valley diverter or rerouting an upper-roof downspout, which means getting on the roof.
• The gutters overflow even when clean, which means resizing or adding downspouts.
• Ice builds up every winter and you are considering heating elements, which call for a licensed electrical contractor in good standing.^[1]

For more, read the exterior answers or look up exterior businesses around Blacksburg. If a section needs refitting or the gutter itself needs work, describe the gutter repair once and local businesses quote it.