Garage Door Brush Seals: A Small Upgrade That Keeps Insects Out

An automatic garage door may look completely closed from the driveway, yet still have substantial openings around its perimeter. When the garage is inspected from inside during daylight, it is common to see light along the sides, across the top or around the bottom corners.

In some installations, these gaps can be close to 10 millimetres. That is more than enough space for cockroaches, spiders, ants, moths and other insects to enter. Dust, leaves, grass clippings and windblown debris can also find their way into the garage.

The solution is usually straightforward: suitable brush seals can be installed around the garage-door opening. However, they are not always included as part of a standard garage-door package, particularly where the property is not subject to bushfire construction requirements.

Why does a closed garage door still have gaps?

A garage door does not operate like a conventional hinged external door. A roller door must move vertically through its guides and roll around its drum. A sectional or panel-lift door travels along tracks before moving into the horizontal position beneath the garage ceiling.

The door therefore needs enough clearance to move without scraping, binding or placing unnecessary load on the automatic opener. The opening itself may also have minor variations in the brickwork, cladding, lintel, floor level or side jambs.

For these reasons, a garage door can be operating correctly while still leaving visible openings around its edges. A bottom rubber seal may be supplied with the door, but this only addresses the area between the bottom rail and the garage floor. It does not necessarily close the gaps down the sides or across the top.

Many homeowners do not notice the problem until they begin finding insects in the garage or see daylight around the closed door.

What is a garage-door brush seal?

A brush seal normally consists of dense synthetic bristles held inside an aluminium or another suitable mounting channel. The channel is fixed beside or above the door so that the ends of the bristles lightly contact the moving door surface.

The bristles flex as the door opens and closes. When correctly selected and adjusted, they close irregular gaps without preventing the door from moving freely.

Depending on the door design, brush seals may be installed:

• along both vertical sides of the opening;
• across the top of the door;
• within or beside roller-door guide tracks;
• along the bottom edge in certain applications; or
• together with a separate rubber bottom seal or floor threshold.

Australian garage-door manufacturers describe brush seals as useful for restricting insects, dust, leaves, draughts and other outside material. They also note that full perimeter brush sealing is not always included in a standard installation and may be supplied as an optional upgrade.

Bushfire requirements are different from ordinary insect sealing

In NSW, the relevant planning term is Bush Fire Prone Land. A property can be checked against the applicable mapping, after which its Bush Fire Attack Level, or BAL, may need to be determined. The required construction measures depend on the assessed risk, the approved design and the relevant development conditions.

Where bushfire construction provisions apply, gaps around a garage door are not treated only as a pest-control issue. They can provide a pathway for windborne embers to enter the garage.

The NSW Rural Fire Service specifically identifies gaps above, beneath and down the sides of garage doors as areas susceptible to ember entry. Its guidance recommends checking the rubber seal along the bottom and fitting a suitable ember seal along the sides and top.

Recent NSW BAL compliance documentation applying AS 3959:2018 also provides for vehicle access doors to be protected by suitable weather strips, draught excluders, draught seals or brushes, subject to the particular door assembly and guide-track arrangement.

This is one reason brush seals may be included automatically in a bushfire-compliant garage-door package but omitted from an ordinary installation.

A generic insect brush should not, however, be assumed to satisfy bushfire requirements. Where the property is on Bush Fire Prone Land, the product and installation must be checked against the BAL report, approved plans, development conditions, door manufacturer’s requirements and applicable construction standard.

What happens outside a bushfire-prone area?

Where bushfire construction provisions do not apply, full perimeter brush sealing may simply be an optional inclusion.

This means a newly completed home may have an automatic garage door, a functional bottom weather strip and visible side or head gaps, even though no brush seals were specified in the contract. The door may satisfy its basic operational requirements without being insect-proof.

The absence of side and top seals is therefore not automatically evidence of defective construction. The following documents should be checked before reaching that conclusion:

• the building contract;
• the inclusions schedule;
• the garage-door quotation;
• the architectural details;
• the BAL report, where applicable; and
• any relevant development-consent or complying-development conditions.

Even when brush seals are not mandatory, they can still be a worthwhile practical upgrade.

Why insects enter through the garage

Garages provide many features that attract insects: shelter from rain, warmth from vehicles and appliances, stored cardboard boxes, bins, pet food, garden products and dark spaces behind shelving.

Once inside the garage, insects may also find a route into the home through the internal access door, gaps around services or openings into the roof space.

The problem can be particularly noticeable when the garage contains a laundry, refrigerator, freezer, home gym, workshop or frequently used storage area. In these situations, the garage is functioning as more than a place to park a car, yet it may still have the perimeter sealing of a basic utility space.

Brush seals will not make a garage completely pest-proof, but they can remove one of the largest and most obvious entry pathways.

Other benefits of brush seals

Insect control is usually the main reason for installing brush seals in an ordinary suburban home, but it is not the only benefit.

Properly fitted seals can reduce the amount of dust, dry leaves, grass clippings and other windblown debris entering the garage. This can make the space easier to keep clean and help protect stored belongings.

They may also reduce visible daylight and some air movement around the door. This can improve comfort where the garage is used as a workshop, gym, hobby space or occasional work area.

However, brush seals should not be presented as complete weatherproofing. They do not necessarily stop water driven beneath the door, correct an incorrectly graded driveway or replace appropriate garage drainage. They also do not turn a standard garage into a conditioned or airtight room.

The complete result depends on the door, side guides, frame, bottom rail, floor level, drainage and seals working together.

Side seals, top seals and bottom seals perform different jobs

It is important to identify where the openings actually occur.

Side brush seals restrict gaps between the moving door and the sides of the opening. Top or head seals address the space above the door. These areas are often responsible for the lines of daylight visible when the door is closed.

A bottom seal addresses the junction between the bottom rail and the garage floor. It is commonly made from flexible rubber or PVC rather than brush material.

If the floor is uneven, one part of the bottom seal may touch the concrete while another section remains open. A larger bottom seal or compatible threshold may help, but the solution must be selected carefully. A poorly positioned floor threshold can trap water inside the garage, interfere with drainage or create an unnecessary obstruction.

The bottom corners also require attention because this is where side seals, bottom seals and guide tracks meet. A door can appear well sealed along each individual edge while still retaining substantial openings at the corners.

The seals must not interfere with automatic operation

More brush pressure does not necessarily produce a better result.

The bristles should maintain light, reasonably continuous contact with the door. If they are installed too tightly, they may increase friction, create noise, damage the finish or place additional load on the automatic opener.

The installer should confirm that the door:

• opens and closes smoothly;
• reaches its correct fully open and fully closed positions;
• does not bind against the new seals;
• remains properly balanced;
• responds correctly to the opener’s safety system; and
• complies with the door manufacturer’s installation requirements.

Hands, tools and measuring equipment should never be placed near the tracks or moving components while the door is operating. Adjustments involving springs, cables, drums or the door-balancing mechanism should be left to a suitably experienced garage-door technician.

Planning brush seals during a new build

The most reliable approach is to decide on perimeter sealing before the garage door is ordered.

The building specification should identify whether the price includes side brush seals, a head seal, the bottom weather seal and any special ember-protection requirements. Simply writing “automatic garage door” in an inclusions schedule does not confirm that the complete perimeter will be sealed.

Early planning also allows the seal carriers to be coordinated with the door guides, brickwork, cladding, garage opening and selected colour. The result is generally neater than adding mismatched components after handover.

The garage floor and driveway levels should also be considered. Even an excellent bottom seal cannot compensate for a badly uneven slab edge or a driveway designed in a way that directs water beneath the door.

After installation, the closed door should be inspected from inside during daylight. Visible openings around the head, sides and corners can then be addressed before the project is completed.

Adding brush seals to an existing garage door

In many existing homes, the door itself does not need to be replaced. Compatible seals can often be retrofitted to a roller, sectional or panel-lift garage door.

The first step is to inspect the closed door and identify the width and location of each gap. The correct brush length, carrier position and mounting method will depend on how the door moves and where clearance is available.

The existing bottom seal should also be inspected for cracking, flattening, shrinkage or missing sections. There is little benefit in installing new side brushes while leaving a substantial opening beneath the door.

After the work is completed, the automatic door should be operated through several complete cycles and its safety functions checked. The brush should touch the door without catching on panel joints, guide hardware or other moving components.

Maintenance should not be overlooked

Brush seals gradually collect dust, cobwebs and small pieces of debris. The bristles may also become flattened, frayed or damaged after years of regular door movement.

They should be inspected periodically with the door stationary. Loose debris can usually be removed with a soft brush or vacuum. Sections that no longer contact the door should be adjusted or replaced.

The bottom rubber seal also requires inspection because it is exposed to repeated compression, vehicle traffic, dirt and changing temperatures.

How ARK Houses can help

At ARK Houses, we can specify appropriate side, head and bottom garage-door sealing when planning a new house, duplex or dual key development, rather than leaving the owner to discover large perimeter gaps after handover. We can also assess an existing automatic garage door and retrofit compatible brush or weather seals where the door and opening are suitable. The sealing arrangement is selected to reduce insect and debris entry while preserving the safe, smooth operation of the door and addressing any applicable bushfire requirements.

Discuss Your New Home