How to Install Gutter Guard on Box Gutters: The Complete 2026 DIY Guide

Installing gutter guard over an internal box gutter requires a different fixing method from protecting a conventional external fascia gutter.

Leaf Stopper COMGUARD™ is designed for compatible internal box gutters where Mesh Shield spans between a wall or vertical upstand and a supported flat-based metal roof profile.

Instead of using CORROGUARD® saddles, DEKAFast saddles or conventional external-gutter Trimets, the standard COMGUARD™ configuration uses:

• Clamper strips on the wall or vertical-upstand side
• Patented Gripit brackets on the supported flat-pan roof side
• Mesh Shield selected to suit the required span
• Colour-matched screws for the applicable components

This guide explains the general installation process, what you need to measure before ordering, how the adjoining roof profile affects the Gripit configuration, and how to preserve future access to the drainage system.

How COMGUARD™ Differs from Other Leaf Stopper Systems

An internal box gutter does not normally present the same fixing arrangement as a standard external gutter.

It may sit:

• Behind a parapet
• Between roof sections
• Along a wall or vertical upstand
• Within the overall roof or building footprint

That means the components used by conventional gutter-edge systems are not automatically appropriate.

CORROGUARD®

Uses Corrofast Saddles on compatible traditional curved corrugated roofing and Trimets at compatible external gutter edges.

TILEGUARD™

Uses Mesh Shield tucked beneath the appropriate tile course and Trimets at compatible external gutter edges.

DEK-762™

Uses DEKAFast saddles on compatible DEK-762-style roof geometry and Trimets at compatible external gutter edges.

DEKGUARD®

Uses patented Gripits on supported flat-based roof pans and Trimets at compatible external gutter edges.

COMGUARD™

COMGUARD™ is the internal box-gutter system.

Its standard configuration uses:

• Clampers on the wall or vertical side
• Gripits on the supported flat-pan roof side

This distinction is critical when reading installation advice online.

What to Confirm Before Ordering COMGUARD™

Do not order from the gutter length alone.

Before installation, record the following information.

1. Box-Gutter Length

Measure each internal gutter run separately.

2. Required Mesh Shield Span

Measure the distance that needs to be protected between the Clamper-side fixing area and the supported roof-side fixing area.

This determines the Mesh Shield width required.

3. Adjoining Roof Manufacturer

Identify the roof-sheet manufacturer where possible.

4. Exact Roof Profile

This is particularly important because Gripit requirements vary between flat-based profiles.

Do not order based only on broad descriptions such as:

• Metal roof
• Deck roof
• COLORBOND® roof
• Flat roof

Identify the actual profile where possible.

5. Drainage Features

Record:

• Downpipe outlets
• Sumps
• Rainheads
• Overflow provisions
• Changes in gutter width
• Unusual flashing
• Roof transitions

These features need to remain functional and accessible after Mesh Shield is installed.

For more detail, read How to Measure for Gutter Guards.

What's Included in a COMGUARD™ Kit?

Current COMGUARD™ kits include:

Mesh Shield

Current width options include:

• 250mm
• 500mm
• 750mm
• 1000mm

The appropriate width depends on the actual box-gutter configuration.

Clamper Strips

Clampers secure Mesh Shield to the wall or vertical-upstand side of the internal gutter.

Gripit Brackets

Patented Gripits fasten the opposite side of Mesh Shield to the supported flat pan of the adjoining metal roof profile.

The required configuration is determined by the selected roof profile.

Colour-Matched Screws

Screws are supplied to suit the Clampers and Gripits in the selected kit configuration.

Does COMGUARD™ Use Trimets?

Not in the standard internal box-gutter configuration.

Trimets are associated with compatible conventional external gutter-edge installations.

Does COMGUARD™ Use Saddles?

No.

COMGUARD™ uses Gripits on the supported flat-pan roof side rather than roof-profile saddles.

How to Install COMGUARD™ on an Internal Box Gutter

The exact fixing layout depends on the roof profile and box-gutter configuration, so the following should be treated as the general installation sequence rather than a substitute for current product instructions.

Step 1: Inspect the Existing Box Gutter

Before installing Mesh Shield:

• Remove existing leaves and larger debris
• Remove significant accumulated sediment
• Check accessible outlets
• Inspect sumps and rainheads
• Look for corrosion or physical damage
• Identify any existing overflow or drainage issue

Do not cover an unresolved drainage problem and assume gutter guard will fix it.

Step 2: Confirm the Mesh Shield Width

Check that the selected Mesh Shield can span the required area between the Clamper side and Gripit fixing area.

Do not automatically use the widest option simply because the gutter is commercial or industrial.

Step 3: Plan the Clamper Fixing Line

One side of Mesh Shield will be retained by Clamper strips against the appropriate wall or vertical upstand.

Before fixing anything, confirm the intended line does not interfere with:

• Flashings
• Drainage features
• Roof movement details
• Other building components

Step 4: Position the Mesh Shield

Position the Mesh Shield across the internal gutter so it can reach:

• The Clamper fixing location on one side
• The supported flat-pan roof fixing locations on the other

The Mesh Shield should span the gutter rather than sitting down inside the drainage channel.

Step 5: Secure the Wall Side with Clampers

Secure the Mesh Shield along the appropriate vertical side using the supplied Clamper strips and screws.

Do not substitute generic flat trims or invent a separate “ledge trim” fixing system unless a project-specific detail explicitly requires one.

Step 6: Secure the Roof Side with Gripits

On the opposite side, use the Gripit configuration specified for the supported adjoining flat-based roof profile.

Gripits attach to supported flat pans.

Do not:

• Replace Gripits with corrugated saddles
• Attach according to an invented universal spacing rule
• Assume every flat-pan profile uses the same Gripit quantity
• Choose Gripits based only on how the roof looks from the ground

The current COMGUARD™ order system calculates the required Gripit configuration from the selected roof profile.

Why Does COMGUARD™ Use Clampers?

Internal box gutters commonly have a wall, parapet or vertical upstand rather than a conventional external gutter lip.

This is why COMGUARD™ uses Clamper strips on that side.

The Clamper provides a dedicated fixing method for Mesh Shield against the vertical surface while the Gripits provide the corresponding fixing points on the supported roof pans.

Together, these components allow Mesh Shield to span across the box gutter rather than occupying the drainage channel itself.

Do Not Obstruct Sumps, Rainheads, Outlets or Overflows

This is one of the most important installation considerations.

COMGUARD™ is a debris-management product.

It does not determine the hydraulic design of the box gutter.

The existing drainage system may include:

• Sumps
• Rainheads
• Downpipe outlets
• Emergency overflow provisions
• Other intentional drainage details

These features should not be unintentionally obstructed by Mesh Shield, fixing components or an access panel.

The overall drainage performance still depends on:

• Roof catchment
• Rainfall intensity
• Gutter dimensions
• Gutter fall
• Outlet capacity
• Downpipe capacity
• Overflow design
• Downstream stormwater

Will COMGUARD™ Stop a Box Gutter Overflowing?

No gutter guard can guarantee that.

COMGUARD™ helps reduce larger debris entering the gutter, which may reduce one potential source of restriction.

It cannot correct an undersized gutter, insufficient outlet capacity, downstream blockage or other drainage defect.

Planning Maintenance Access with EasyAc®

EasyAc® is an optional access product that can provide local inspection access through compatible Mesh Shield.

Possible access locations can include:

• Important downpipe outlets
• Sumps
• Long gutter runs
• Corners
• Sediment-prone areas
• Other locations where future inspection is likely

There is no universal requirement to install an EasyAc® at every downpipe, rainhead or sump.

Placement should reflect the specific drainage and maintenance layout.

What EasyAc® Can Do

EasyAc® can provide local access for:

• Visual inspection
• Local flushing
• Checking accessible sediment
• Inspecting nearby gutter-floor conditions

What EasyAc® Cannot Guarantee

An access panel cannot automatically:

• Clear a deep downpipe blockage
• Clear underground stormwater
• Make the gutter maintenance-free
• Confirm the condition of an entire long gutter run from one opening

Choosing Mesh Shield for COMGUARD™

Standard Mesh

• Aperture: 3.5mm × 3.5mm
• Thickness: 0.55mm aluminium
• Material: Non-combustible
• Use: General leaves and larger debris

Premium Mesh

• Aperture: 3.5mm × 3.5mm
• Thickness: 0.80mm aluminium
• Difference: Approximately 46% thicker than Leaf Stopper Standard Mesh

Premium Mesh is thicker—not finer.

Do not automatically prescribe Premium Mesh because the site is windy, commercial or surrounded by heavy debris unless the project specification calls for the thicker option.

Fine Mesh

• Aperture: 1.8mm × 1.8mm woven mesh
• Thickness: 0.40mm aluminium
• Use: Finer debris and applicable BAL-rated applications

If bushfire compliance matters, confirm the requirements applying to the specific building and application rather than assuming Fine Mesh automatically makes the entire system or building compliant.

See the Leaf Stopper Bushfire Protection information for further guidance.

Can You Install COMGUARD™ Yourself?

DIY installation may be possible where the application is straightforward and the roof can be accessed safely by a competent person.

However, COMGUARD™ is commonly used on commercial and industrial buildings where:

• Roof heights are greater
• Access is more difficult
• Gutter spans are longer
• Roof geometry is more complex
• Formal work-at-height controls may apply

Professional installation is generally preferable for:

• High roofs
• Multi-storey buildings
• Commercial or industrial properties
• Complex parapets
• Difficult roof transitions
• Fragile or difficult-access roof areas
• Projects where the installer cannot safely perform the work

You can find a Leaf Stopper installer if the project is unsuitable for DIY work.

Should You Follow a Universal Screw Spacing?

No.

Do not invent a generic COMGUARD™ fixing interval such as:

• Every 250mm
• Every 500mm
• Every second pan
• A fixed number of screws per metre

The relevant Gripit requirement depends on the selected roof profile, while other fixing details should follow the current instructions for the kit and application.

How Much Should COMGUARD™ Mesh Overlap?

Again, do not use an invented universal overlap dimension.

If multiple Mesh Shield sections need to be joined, use the current Leaf Stopper installation detail applicable to the project rather than assuming a generic 20mm, 30mm or other fixed overlap.

Maintaining a Box Gutter After COMGUARD™ Installation

COMGUARD™ helps reduce larger debris entering the channel, but the gutter still needs to remain inspectable.

Potential maintenance issues include:

• Wet leaves remaining on Mesh Shield
• Branches or storm debris
• Fine sediment passing through the mesh
• Debris near outlets
• Moved or damaged components
• Changes elsewhere in the drainage system

There is no universal twice-yearly or annual inspection rule.

Inspection frequency should reflect:

• Nearby vegetation
• Dust levels
• Roof exposure
• Local weather
• Seasonal leaf fall
• Previous drainage history
• Significant storm events

For a dedicated maintenance process, read Preventing Blocked Box Gutters: The Essential Maintenance Checklist.

COMGUARD™ Installation Checklist

Before installation, confirm:

• □ Internal box-gutter length measured
• □ Required Mesh Shield span measured
• □ Roof manufacturer identified
• □ Exact roof profile identified
• □ Correct Gripit configuration selected
• □ Correct Mesh Shield width selected
• □ Mesh grade selected
• □ Existing debris removed
• □ Sumps identified
• □ Rainheads identified
• □ Downpipe outlets identified
• □ Overflow provisions identified
• □ Any EasyAc® locations planned
• □ Safe access assessed

Choose the Correct COMGUARD™ Configuration Before Installing

The main installation principle is simple:

COMGUARD™ spans a compatible internal box gutter using Clampers on the wall/upstand side and Gripits on the supported flat-pan roof side.

The details around that basic arrangement depend on the actual gutter and roof profile.

That is why measuring and profile identification should come before cutting or fastening Mesh Shield.

If you are still deciding what configuration you need, visit the COMGUARD™ information page.

If you are comparing box-gutter protection options generally, read Best Box Gutter Leaf Guard Systems for Australian Properties.

For measurement help, use the Gutter Guard Measuring Guide.

When you're ready, shop Leaf Stopper gutter guard systems or find a professional installer.

Frequently Asked Questions

How is COMGUARD™ attached to an internal box gutter?

Clampers secure one side of Mesh Shield to the appropriate wall or vertical upstand, while Gripits secure the opposite side to the supported flat pan of the adjoining metal roof profile.

Does COMGUARD™ use Trimets?

Not in the standard internal box-gutter configuration. Trimets are used in other Leaf Stopper external gutter-edge systems.

Does COMGUARD™ use roof saddles?

No. COMGUARD™ uses Gripits on supported flat roof pans.

What widths does COMGUARD™ come in?

Current Mesh Shield options include 250mm, 500mm, 750mm and 1000mm widths.

How do I know which Gripits I need?

Identify the exact adjoining roof manufacturer and profile. Current COMGUARD™ product configuration uses the selected roof profile to determine the appropriate Gripit requirement.

Can COMGUARD™ prevent a box gutter overflowing?

No gutter guard can guarantee that. It may help reduce debris-related restrictions, but drainage performance still depends on the complete gutter, outlet, overflow and stormwater design.

Do I need an EasyAc® at every downpipe or sump?

No. Access-panel locations should be selected according to the actual gutter layout, important drainage points and future maintenance requirements.

Can I install COMGUARD™ myself?

Possibly, on a straightforward and safely accessible application. Professional installation is recommended for high, complex, commercial, industrial or difficult-access roofs.

How often should a protected box gutter be inspected?

There is no single interval suitable for every property. Inspection frequency should reflect vegetation, dust, roof exposure, weather and drainage history.

Does COMGUARD™ make the box gutter AS/NZS 3500.3 compliant?

No. Gutter guard does not establish the hydraulic compliance of the complete stormwater system.