Wasps, Mice and Squirrels in the Gap Under Your Gutter Guard

A gutter guard is a cover, and every cover has an edge. On a St. Louis house that edge sits a few inches above the trough, right where the guard meets the gutter lip or the fascia. That gap is where wasps start their paper nests, where mice find a dry place to winter, and where squirrels chew at foam or plastic guards that were never built to stop them. Many homeowners find a nest in the gutter line only after the guard is already on, so the question worth asking before the order is what the guard does at the edge, not only what it does to leaves.

Gutters and guards

Gutter guards fall into a few broad families. Screens and mesh rest on the trough and let water pass through while keeping debris on top. Foam inserts sit in the trough and filter water through a block of foam. Brush guards use bristles along the trough. Surface tension or reverse curve guards send water over a curved lip. Each family leaves a different opening, and the opening decides which animals can get in.

A wasp is not interested in the size of a leaf. It is interested in a sheltered, dark cavity that stays out of the rain and sits above the reach of the ground. Under a guard that sits a little proud of the trough, the space between the guard and the gutter back can look like a shelf. Paper wasps and mud daubers both use spots like this. Mud daubers build tubes out of mud, which is one reason a homeowner may spot a grey crust in a trough corner before anything else. A nest does not have to be large to matter, and wasps defend it. A worker that flies out of a gap at the edge of a ladder is a real hazard to anyone already up the ladder, so it is worth checking from the ground before climbing.

Mice are a different problem. A house mouse can squeeze through an opening about the width of a pencil, and a gap that size is easy to miss from the ground. Mice use the trough as a nest once debris has collected, and debris collects faster when a guard has trapped it in the first place. Droppings in the trough or dark stains on the fascia below the gutter are typical signs. A mesh with openings too large for a mouse will keep the rodent out but may let a wasp in, so the two concerns have to be weighed together.

Squirrels chew. Foam inserts and some plastic guards become a target once a squirrel has found the eave, and a chewed section opens a path for everything else. Squirrels also use the top of a guard as a runway, which loosens fasteners over time. Oaks and hickories are common on older St. Louis lots, so on a house under those trees the squirrel question is a practical one, not a remote possibility.

What to look for before the order

Start with the fascia behind the gutter. Look for gaps between the gutter back and the fascia board, because a guard can hide a gap that lets wildlife in while the homeowner assumes the edge is closed. Check whether the guard edge is tucked under the first course of shingles, sealed with a fascia cover, or simply left open. Ask the crew to show how the guard closes at the wall, because the wall is where gaps tend to get missed.

Next, look at the mesh size from a few feet away with a phone camera zoomed in. If you can see daylight through the mesh at a normal distance, a mouse may be able to pass through it as well. Foam inserts are different. They are not a barrier to a determined animal, and they hold moisture when a nest is started inside them. A foam insert that has been in place for a season may show dark tunneling, which is a sign that an animal has been using it rather than only water passing through.

Finally, walk the downspouts. Wasps often nest in the elbow where a downspout turns, and a guard does nothing to stop that. A screen in the downspout outlet is a separate item. Some homeowners ask for one, and others would rather keep the outlet open so it can be cleared. That is a decision for the household rather than a fixed rule, and it should be written on the scope either way.

Checking for a nest without getting stung

Do not start by climbing. Look at the gutter line from the ground in the morning, when wasps are slower, and watch the corners and the area under the guard edge. Count the wasps coming and going. A few around a new nest in spring usually means a single founding queen or a small colony. A steady flow of wasps in late summer means the colony has grown and the nest is larger. In either case, a homeowner should not open the guard edge alone. Call a licensed pest control operator for an active nest. That is a separate trade from roofing, and a roofer who finds an active nest will want it dealt with before the guard is lifted.

When the nest is gone and the edge is clear, the guard can be lifted and the edge sealed. Ask whether the sealing is part of the scope. A written scope that says only "install guards" does not say what happens at the edge, so a homeowner who wants wildlife kept out should ask for the edge detail in writing, with photographs, before the order goes in.

What it costs

Cost depends on what has to be added to the basic guard. A plain mesh with an open edge costs less than a guard with a closed edge, a fascia cover, or a separate screen at the downspout outlet. Some homes need a different guard entirely, because the existing gutter is too worn to hold the one planned. Ask for each item on its own line so you can see what is being charged for wildlife protection and what is only the guard itself. If a quote is one number with no detail at the edge, the wildlife question has not been answered.

Repairs after animals have been inside are a separate matter from prevention. Insulation in the fascia cavity, torn foam, and chewed fascia boards each get their own line. Keys documents what is found and puts a written scope with photos and measurements in your hands, so you can compare it against other written proposals with the same level of detail.

What to ask

• Where does the guard edge meet the gutter back, and is that gap closed with a cover, a seal, or nothing at all?
• What mesh size is being used, and can you show me a sample in daylight?
• Is the downspout outlet covered, and who clears it if it clogs?
• Does the quote show the fascia cover and the edge closure as separate lines?
• If a nest is found during the work, who removes it, and who pays for the pest control visit?
• Will the crew photograph the edge detail before and after the guards go on?

Keys Roofing can be reached at (314) 220-2333 to talk through the gutter line on your house before any guard is ordered.