NDSU Extension recommends tight-fitting screens, especially on upstairs and attic windows and vents, before the cooler months. Sealing the openings on the warm south and west walls is the most useful step a homeowner can take before fall, because those are the spots where overwintering insects gather.
Key takeaways
- NDSU advises tight-fitting screens, especially on upstairs and attic windows and vents.
- The warm south and west walls are where overwintering insects gather as temperatures cool.
- A screen that has pulled away from its frame is enough for small insects to get through.
- Gaps around pipes, cables, dryer vents and siding joints are common entry routes to check.
- Sealing is cheap compared with cleaning up after insects have reached the living areas.
Why does sealing come before the cooler months?
Sealing works best before insects have found their way inside. As temperatures start to cool, the insects that overwinter in buildings slow down and look for shelter, and the openings they use are the ones that matter. Closing them early is the simplest protection.
North Dakota State University Extension reports that the insects which overwinter in homes start looking for shelter as temperatures cool, and that they gather on warm walls. A house sealed before that period gives them fewer routes, and the work is done before the activity begins.
Doing the work in late summer also means it can be done in comfortable weather, on a ladder that is safe to use and with time to check each repair. Waiting until insects are already in the living room makes the job harder and more urgent.
Which openings should I check first?
Start with the upstairs and attic windows, the attic vents and the gaps around the window frames on the south and west walls. NDSU advises tight-fitting screens for those openings. Then check the siding joints, the utility penetrations and the door sweeps.
Upstairs and attic windows are the openings NDSU points to most clearly, because they are often the easiest route into the upper rooms and the roof space. Check each screen from inside, and make sure it fits the frame along its full length. A screen with a corner that has come away is enough to let a small insect through.
The vents in the attic and the soffit deserve the same attention. A vent cover with a broken louvre or damaged mesh is a route in, and it sits on the warm side of the roof where insects gather. Note the vents on each side of the house, since the south and west ones tend to see the most activity.
How do I check a screen or a vent cover?
Hold a light against the screen from inside and look for tears, gaps and places where the mesh has pulled away from the frame. For a vent cover, check the louvres and the mesh from outside. A repair or a replacement is usually a simple job.
A screen that is loose in its frame is the most common repair. Press the frame gently and check that the spline holds the mesh firmly. A replacement screen is inexpensive and fits most standard windows, and a helper can make the job faster.
For a vent cover, look for corrosion, broken louvres and mesh that has torn. A cover that no longer closes fully should be replaced. Work on a vent from the ground or with a helper, and do not lean out of a window to reach one.
What about the gaps around pipes, cables and dryer vents?
Gaps where a pipe, a cable or a dryer duct enters the wall are common entry routes, and they are often overlooked. A foam or sealant product designed for the purpose, with a mesh where the gap is large, closes them. Check each penetration on the outside and the inside.
A pipe that enters the wall through a hole larger than the pipe leaves a route that is easy to miss. The gap can be packed with steel wool or mesh first, then covered with a sealant. The seal should be checked each year, since it can crack as the building moves.
A dryer vent needs a cover that closes when the dryer is off, and the surrounding gap sealed. Keep the duct clear and check the vent after each season. A blocked or damaged vent is also a fire concern, so it is worth checking regardless of the insects.
How do I handle the warm south and west walls?
The warm south and west walls collect insects as the sun heats them in the afternoon. Walk those walls on a sunny afternoon and note where insects gather, then check the joints, window frames and vents that sit on those walls.
Insects gather on warm surfaces, and a sunny wall is a meeting point before they look for a way in. A siding joint, a corner trim or a gap under a window frame on that side of the house is worth checking first. Note the spots you see activity, since those are where the sealing should start.
Planting against the wall can make the gap harder to see and can give insects a bridge. Trim back shrubs and move mulch from the foundation, and keep a clear strip at the base of the wall so that the joints can be checked.
When should I hire a technician instead of doing it myself?
Screens, door sweeps and simple sealing are often DIY jobs. Repairs to siding, soffits, roofs, window frames and the foundation are better done by a tradesperson. A technician can inspect the whole building and tell you which repairs fit which trade.
A homeowner can usually handle a screen, a sweep and a small sealed gap. A ladder job, a repair that involves cutting into siding, or any work near a flue or electrical box should be left to the right trade. The safety risk of a fall or an electrical fault is not worth the saving.
A visit from a technician is useful when the openings are hard to find or many. The report lists each one with the repair it needs, so you can do the simple ones yourself and get a quote for the rest.
What does a practical autumn sealing check look like?
Plan one walk round the house in late summer, one check of the attic and upstairs rooms, and a second check after the first cold snap. Keep a list, date each item and tick it off when it is closed.
A walk round the house on a dry day, with a notebook and a light, catches most of the openings. Start at the south-west corner, since those walls collect the most activity, and work round. Note the screens, vents, joints, penetrations and door sweeps as you go.
A second check after the first cold snap shows which openings have reopened or which new ones have appeared. Keep the list for the next year, since the same weak points can recur season after season.
What about the attic and the roof edge?
The attic is where insects that have come in through the vents often collect, and the roof edge is where the soffit and the vent meet the wall. Check the attic from the access point where it is safe, and look at the soffit and roof edge from the ground or with a helper.
A torch shows daylight through a gap in the attic floor or the roof sheathing, and a gap there is a route into the living space. Look for droppings, nests or insects along the rafters and near the vents, and note any place where the insulation has been disturbed.
Roof-edge and soffit work is a job for a tradesperson when it involves a ladder, a roof or cutting into the structure. A technician can identify the openings and say which repair fits which trade, which is safer than attempting the work from a ladder.
How do I keep the openings closed through the winter and spring?
Check the seals and screens once in the late winter and again in spring, when the building has settled and the weather has tested the joints. A repair made in autumn can loosen over a long season, so the check is worth repeating.
A sealant can crack as a building moves, and a screen can sag or tear in wind and snow. A short check of the openings after the winter shows which repairs have held and which need renewing before the next autumn.
Keep the list of openings from the first check and tick each one off. The list becomes a yearly maintenance plan, and it is much quicker to work from than starting again each season.
Frequently asked questions
Why does NDSU say tight-fitting screens?
NDSU Extension advises tight-fitting screens, especially on upstairs and attic windows and vents, because loose screens let small insects through. A screen that fits the frame along its full length keeps the insects out and is a simple fix.
Do sealed houses still get insects?
A house can be sealed well and still have insects if a gap is missed or a screen is damaged. Checking the openings each autumn is the reliable way to keep the building closed.
What should I use to seal a gap?
Use a product made for the purpose. For larger gaps, pack mesh or steel wool first, then cover it with a sealant. A technician can recommend the right combination for the gap in front of you.
Is it worth sealing the attic vents?
Yes. Attic vents are among the openings NDSU points to, and a vent cover with a broken louvre or damaged mesh is a route in. The vent should still allow air to move, so a fine screen or a repaired cover is the usual fix.
When is the best time to seal?
Before the cooler months start, in dry weather, when you can work safely on a ladder and check each repair. A second check after the first cold snap is also worth doing.
Is it worth sealing the whole house or only the warm side?
Start with the warm south and west walls and the attic, since those collect the most activity. Then work round the rest of the house. A whole-house check is useful if the building has many openings, and a short check is enough for a small, recently repaired house.
Who can I call if I find an opening I cannot fix?
Ask a technician to inspect the opening and recommend the right trade. The report will name the repair and the kind of tradesperson it needs, and you can compare quotes from that tradesperson on the repair alone.
Sources
- North Dakota State University Extension, Watch for fall-invading insects in the home (2023)
- North Dakota State University Extension
This guide is general information for Burleigh County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.