How to install strip drains for a patio, driveway or garage entrance

🏗️ Installing strip drains to stop water pooling at patios, driveways and garage entries

Why are strip drains essential for Australian homes?

Strip drains, also called channel drains, are one of the quickest and most effective ways to intercept surface water before it reaches doors, paving edges or garage slabs. For Australian homes dealing with heavy rain, the key is not just laying the drain, but setting the correct fall, connecting it to a legal discharge point, and compacting the surrounding base so it lasts.

This guide covers how to plan, excavate and install a strip drain across a patio, driveway or garage entrance, with practical DIY advice and trade-standard methods suited to Australian conditions.

What skill level is required to install strip drains in Australia?

Intermediate — Estimated time: 1–2 days

What tools are needed for strip drain installation in Australia?

What materials are essential for installing strip drains?

Safety Requirements

Step-by-Step Guide

Step 1: Assess where the water is coming from

1️⃣ Identify the water path

Watch the area during rain if possible, or hose test it to see exactly where water pools and which direction it flows. The ideal strip drain position is usually directly in front of a garage door, across the low side of a patio, or at the threshold where paving meets the house.

You want the drain to intercept runoff before it reaches the building. If the whole paved area falls back toward the house, a strip drain alone may not solve the issue and some regrading may also be needed.

💡 A strip drain is best for surface water. If you have groundwater seepage or saturated garden beds, you may also need subsoil drainage like ag pipe.

Step 2: Confirm the legal discharge point

2️⃣ Plan where the water will go

A strip drain is only as good as its outlet. You need a lawful place for collected water to discharge, such as:

The outlet pipe needs continuous fall, ideally around 1:100 to 1:200 depending on the site and pipe size. Avoid creating a new low spot where water can back up into the channel.

⚠️ Some councils require approval for new stormwater connections, especially at driveways or where kerb discharge is involved.

Step 3: Choose the correct drain class and size

3️⃣ Match the drain to the load

For a patio or foot traffic area, a domestic channel drain around 100 mm internal width is often sufficient. For a driveway or garage entrance, choose a heavier-duty unit designed for vehicle loads.

As a rule:

Check the manufacturer’s load class and installation requirements. A drain that is fine for pedestrians can fail quickly under car tyres if installed at a garage or driveway.

💡 Don’t save money by using a light plastic grate in a trafficable area. Replacing crushed grates later costs more than buying the right system upfront.

Step 4: Set out levels and falls

4️⃣ Mark the finished height

Set a string line or laser level to establish the finished surface level and the top of grate level. The grate should usually finish:

Give the channel itself a slight fall toward the outlet unless using a pre-fall system. For surface paving approaching the drain, aim for a fall of about 1:80 to 1:100 toward the channel where practical.

Take your time here. Most drainage failures are level errors, not product failures.

Step 5: Cut and remove the existing surface

5️⃣ Open the trench line

Mark the drain run and cut both sides cleanly through the paving or concrete. Remove enough material to allow:

For patios, this may mean lifting pavers. For driveways or garage aprons, you may need to saw-cut and jackhammer concrete. Keep edges neat so reinstatement is easier.

If the run is long or the slab is thick, hiring a 1.7t–2.5t mini excavator and jackhammer attachment can save serious time. For a once-off DIY job, hire usually makes more sense than buying. Buying only stacks up if you’ve got repeated landscaping or renovation work planned.

Step 6: Excavate to depth

6️⃣ Dig for base, drain and pipework

Excavate the trench deep enough to accommodate:

Depth varies by product, but many installations end up around 150–300 mm deep, sometimes more where outlet pipes need extra cover or fall.

Keep the trench base firm and uniform. In soft ground, lay geotextile and rebuild with compacted crushed rock before bedding the drain.

⚠️ Safety — Recheck services from 📞 Dial Before You Dig (1100) before deepening any trench or extending toward existing stormwater lines.

Step 7: Prepare and compact the base

7️⃣ Build a stable foundation

Place and compact crushed rock base to the required level. Use a plate compactor to achieve a solid founding surface. Over that, place bedding concrete or the manufacturer’s specified base.

A stable base stops the drain from rocking, settling or cracking under load. This is especially important at garage entries and driveways where wheel loads are concentrated.

For trafficable installations, follow the manufacturer’s side encasement requirements carefully. Many channel drains need concrete haunching on both sides to prevent movement.

💡 Poor compaction is one of the biggest reasons strip drains sink and hold water after the first wet season.

Step 8: Install the outlet pipe

8️⃣ Connect to stormwater properly

Fit the outlet to the lowest point of the strip drain run and connect the pipework to the legal discharge point. Use 90 mm or 100 mm PVC as required, with solvent-welded joints.

Maintain a consistent fall along the pipe run, ideally at least 1:100 where site conditions allow. Avoid flat spots, backfalls or sharp changes in direction without access points.

Before covering the pipe, run water through to confirm it drains freely and doesn’t pond in the line.

Step 9: Lay and align the strip drain

9️⃣ Set the channel in place

Assemble the drain sections in sequence, fit end caps, and place them on the bedding. Align them straight and set them to final height using your laser, string line and spirit level.

Check three things repeatedly:

If the channel is too high, it becomes a trip hazard and catches tyres. If too low, it creates an ugly trough and may undermine adjacent paving.

Step 10: Concrete haunch and secure the drain

🔟 Lock it in so it won’t move

Haunch both sides of the drain with concrete as required by the drain manufacturer. In vehicle areas, this side support is critical. The concrete should bear against the channel body without pushing it out of alignment.

Recheck levels before the concrete sets. Keep the grate fitted during this stage if the manufacturer recommends it, as it helps maintain shape and spacing.

For paver areas, ensure the bedding and edge support tie neatly back into the surrounding surface.

Step 11: Reinstate paving or concrete

1️⃣1️⃣ Finish the surrounding surface

Re-lay pavers, pour concrete infill, or make good the edges so the finished area drains cleanly to the grate. Maintain a smooth transition with no lips or depressions.

If reinstating concrete at a driveway or garage entry, consider tying new concrete into the old with dowels where appropriate. Finish the surface neatly so water sheds toward the channel, not away from it.

Step 12: Test before handover

1️⃣2️⃣ Run a full water test

Flush the channel and outlet with a hose and simulate heavy flow across the paved area. Check for:

Clean out debris, remove slurry and confirm the grate is securely clipped or fastened.

A successful install should collect water fast, move it away cleanly, and sit flush with the finished surface.

Common Mistakes to Avoid

Pro Tips

Recommended Tools

🔧 Equipment Required

🔧 Recommended Equipment