Why Sealing Gaps and Cracks Is the Most Effective Long-Term Spider Control Method

Most homeowners assume that once a pest controller treats their property, the spider problem is solved. It’s a reasonable assumption, but it misses a key part of how spider control works long-term.

Treatment eliminates the spiders already present. It doesn’t stop new ones from moving in afterwards. If entry points around your home stay open, spiders from the surrounding environment will keep finding their way inside, and the results of even a well-applied treatment will fade. Sealing is what makes treatment actually last.

July 14, 2026

Spider Control

Mac Naji

Last updatedAugust 29, 2026

Why Spiders Keep Entering Treated Homes

Residual treatment products break down over time. That’s expected, but it means the protective barrier a treatment provides has a limited window.

Once the active product on a surface degrades, new spiders moving in from the garden, neighbouring properties, or nearby bushland encounter no barrier at all. They simply walk in through whatever gap gets them there. Without physical proofing to close those gaps, re-entry is inevitable, no matter how effective the original treatment was. This is the main reason properties treated once still see spiders return a few months later.

The Most Common Spider Entry Points in Sydney Homes

Gaps around window frames and door seals are the primary indoor entry routes. These small openings are easy to overlook but provide constant access for smaller species looking for shelter.

Weep holes in brick cavity walls allow ground-dwelling species, including redbacks, direct access into wall cavities.

If someone is bitten: the two protocols are opposite. Funnel-web (and mouse spider): treat it as a medical emergency. Call 000. Apply a pressure immobilisation bandage as you would for snakebite, firmly over the bite and then along the whole limb, splint the limb and keep the person as still as possible. Antivenom is available and effective. Redback: do not apply a pressure immobilisation bandage. Redback venom acts slowly and local pressure makes the pain worse. Apply an ice pack to relieve pain and seek medical attention, calling 000 if the pain is severe, spreading, or the patient is a young child. For any other Sydney spider, including huntsman and white-tailed spiders, wash the area, apply a cold pack and see a doctor if pain, swelling or infection develops.

These holes are a necessary part of the building’s ventilation, so they can’t simply be sealed shut.

Gaps around pipe penetrations, where plumbing enters external walls, create direct corridors from outside straight into wall spaces and under floors.

Deteriorated eave linings and fascia board gaps give roof-dwelling species like huntsman spiders access to the interior, often unnoticed until activity shows up inside ceiling spaces.

Gaps under door thresholds, particularly at garage and laundry doors, are frequently overlooked entirely, despite being one of the easiest entry points for ground-level species to use.

Book a professional inspection today

If your home keeps attracting spiders, no matter how often you treat it, the entry points are likely still open. Pest Power Sydney carries out full property assessments that identify exactly where spiders are getting in, alongside treatment itself, rather than treating symptoms on repeat.

Why Older Sydney Homes Have More Entry Points Than Newer Builds

Federation homes, post-war brick properties, and terrace houses develop natural gaps through decades of timber movement, mortar deterioration, and general building settlement. None of this happens through neglect. It’s simply what ageing building materials do over time.

These properties need a more thorough proofing assessment because entry points tend to be widespread and often aren’t obvious without a professional inspection. A gap that’s opened up behind a fascia board or around a shifted window frame won’t necessarily be visible during a casual look around the property.

What Materials Are Used for Effective Spider Proofing

Not all sealing materials prevent spider entry equally, and using the wrong one in the wrong spot can leave gaps that look sealed but aren’t.

Standard silicone around pipe penetrations is a reasonable starting point, but it needs to be applied comprehensively. Door seals and brush strips at thresholds close off common ground-level entry routes at garage doors, laundry doors, and external entries. Stainless steel mesh over weep holes allows necessary airflow while physically blocking spider access. Eave and fascia repairs address roofline entry points commonly missed in surface-level treatments.

Why Proofing and Treatment Need to Work Together

Sealing alone doesn’t address the population already established inside the home or around its exterior. A perfectly sealed house with an existing spider population indoors still has a spider problem; it’s just contained rather than resolved.

Proofing and professional spider pest control treatment combined produce results neither achieves alone. Treatment clears the existing population. Proofing prevents the next generation from moving in to replace it. Doing one without the other leaves a gap in the process, and that gap is usually where the problem returns from.

What a Professional Spider Inspection Covers That a Homeowner Assessment Misses

Identifying all active spider entry points in a Sydney home requires knowing what to look for and, just as importantly, where to look. Roof void access points, subfloor vent conditions, and gaps behind cladding aren’t visible from a casual walkthrough.

A licensed spider exterminator inspects these areas systematically, checking spots that get missed in a homeowner’s usual once-over. That level of detail is what separates a proper long-term proofing job from a quick fix addressing only the entry points that happen to be obvious.

The Bottom Line

Chemical treatment alone was never designed to be a permanent solution on its own. It removes the spiders there right now, but it can’t stop new ones from walking in through gaps still open. Sealing entry points closes that gap, literally, and it’s the difference between a treatment that holds and one you’ll be repeating every few months.

If you want spider control that actually lasts, treatment and proofing need to happen together. Pest Power Sydney combines both in a full property assessment, so you’re not just clearing spiders out, you’re closing the gaps they were using to get in.

Having it dealt with properly

Sealing is the durable half of spider control, and finding the gaps that matter, including weep holes and subfloor vents, takes an inspection rather than a walk around the garden.

A spider treatment starts outside, because that is where the population lives: eaves, fascia, window frames, the base of the building, fence lines and the subfloor, with internal work targeted at the places spiders actually shelter rather than the middle of a room. Spider treatments start from $89 for a standard home or unit and carry a six-month warranty. Pest Power Sydney provides spider pest control in Sydney, and the work is carried out by the owner-operator, Mac Naji, and his technicians, who are the people customers name in the reviews. Call 0412 931 208 for a quote or a same-day inspection.

If you are working through this, it is worth also reading why spider treatment has to cover inside and outside, how long a spider treatment lasts and the Sydney spider calendar through the year.

Pest Power Sydney holds a 5.0 rating from more than 320 Google reviews. The themes Google pulls out of those reviews most often are a knowledgeable technician, a thorough inspection and the six-month warranty.

Frequently Asked Questions

Does sealing gaps actually stop spiders getting inside?

Sealing is the one measure that keeps working after a treatment has broken down. A spray loses effect over weeks; a sealed gap stays sealed. Most spiders found indoors walked in through an opening rather than hatching inside, so closing entry points treats the cause rather than the symptom.

Which gaps let the most spiders into a Sydney home?

Is sealing better than spraying for long-term spider control?

Will sealing gaps help with funnel-web spiders?

How long does gap sealing keep working?

How do I book spider control with Pest Power Sydney?

Sealed the gaps and still seeing them? Proofing and treatment work as a pair, not as alternatives. Pest Power Sydney provides spider treatment and entry-point sealing.