Termite Barriers in Sydney: What They Are and Which One Suits Your Home

A termite barrier is anything that stops subterranean termites getting from the soil into your house without being seen. It doesn't kill a colony on its own and it doesn't make a house termite-proof. What it does is close off the hidden ways in, so termites either hit treated ground or are forced out into the open where an inspection picks them up.

Most of the termite work I do on Sydney houses is Coptotermes, a subterranean termite. It nests in the ground, in a stump or tree, or under the building, and travels to the timber through the soil. That's why barriers go where the house meets the ground.

I install four kinds. Here's what each one is, who it suits, and what the warranty covers, so you can come to the inspection knowing the options.

The four types of termite barrier I install

1. Chemical barrier (Termidor)

A chemical barrier is a treated zone of soil around and under the house. I trench and treat the soil along the outside walls and, where I can get to it, the subfloor, using Termidor. Termites tunnelling through that soil come into contact with it.

It suits most existing homes, slab or suspended floor, where the soil around the house can be reached.

Warranty: 8 years. This is my own installation warranty. It covers free re-treatment of the area termites crossed. It doesn't cover building damage or repairs, and it stays valid only with a yearly inspection by me.

More detail: chemical barrier treatment and how long a chemical barrier lasts.

2. Physical barrier (TermSeal and Green Zone)

A physical barrier goes in while the house is being built. Sheeting goes under the slab and collars go around the pipes that come up through it, so termites can't come up through the slab or around the pipe penetrations unseen. I install TermSeal and Green Zone, to AS 3660.1.

It suits new builds and extensions only. It can't be retrofitted under an existing slab.

Warranty: - TermSeal: 50 years. That's TermSeal's product warranty, kept valid with a yearly inspection by me. I'm TermSeal accredited. - Green Zone: the manufacturer's 50-year warranty, valid while I do the yearly inspection.

More detail: pre-construction termite barriers.

3. Reticulation system

A reticulation system is a network of pipes laid in the ground around the house. Instead of digging a new trench each time the chemical needs topping up, the pipes are refilled with termiticide on a schedule, usually every 3 to 5 years. I've always installed these.

It suits new builds, where the pipes can go in before the paths and gardens. I only install reticulation on new builds.

Warranty: protection lasts while the system is refilled on schedule and inspected yearly by me.

More detail: termite reticulation systems.

4. Baiting and monitoring (the alternative)

Baiting doesn't put a treated zone around the house. Stations go in the ground around the house and get checked. Bait goes in once termites turn up in a station. I use Nemesis and Trelona.

It suits homes where a chemical barrier is hard to do properly:

• pavers or concrete right up to the walls
• a zero-lot boundary, where one wall sits on the boundary
• water nearby, like a pool, creek or pond
• renovations coming up that would disturb a barrier

Cover: baiting is covered while it's monitored.

More detail: termite baiting and monitoring and chemical barrier or monitoring system.

What a barrier won't do

A barrier is one part of protecting a house, not the whole job. A few things it can't do:

• It won't make the house termite-proof. It closes off the hidden ways in. Termites can still try to build over it, which is why the yearly inspection matters.
• It won't fix the conditions that draw termites in. Leaking taps, blocked downpipes, timber against the soil and garden beds piled up against the walls all help termites. They need fixing whatever barrier you have.
• It won't kill a colony that's already inside. If there's live activity, that's dealt with first.
• It won't stay intact if the ground is dug up. New paths, decks, garden beds and plumbing work can cut through a barrier. See "Renovations and landscaping" below.

Keeping a barrier working

Every barrier I install depends on someone looking at the house once a year. The yearly inspection is how I catch a mud lead going over a barrier, a garden bed built up against the wall, or a section that's been disturbed. It's also what keeps the Termidor, TermSeal and Green Zone warranties and reticulation cover valid.

Between inspections, the simple things help: keep the edges of the house clear so you can see the slab edge or the base of the walls, keep timber and mulch off the soil against the house, and fix leaks quickly.

How to choose

The right barrier comes down to whether the house is built yet, what sort of floor it has, and how much of the ground around it I can get to. I make the call on site.

New build or extension

Before the slab is poured is the only time a physical barrier can go in. TermSeal or Green Zone sheeting and collars go under the slab, to AS 3660.1. A reticulation system can go in at the same stage, before the paths and landscaping.

Existing home on a slab

You can't get under a slab once it's poured. The options are a chemical barrier around the outside, or a monitoring system.

Existing home on a suspended floor

With a subfloor, I can treat around the piers as well as the outside walls. Monitoring is still an option if the subfloor is tight or the outside is mostly concrete.

If termites are already there

A barrier isn't the first step if there's live activity. The colony comes first, and colony treatment carries no warranty. Once it's dealt with, a barrier or monitoring protects the house from there on.

There are times a chemical barrier isn't the right call at all. I go through them in when a chemical barrier isn't the right choice.

The warranties side by side

Renovations and landscaping

If you renovate or landscape and disturb a barrier, cover for that section is limited until I've checked it and restored it. It doesn't void the whole warranty. Call me before the work starts, or as soon as you know the ground's been dug up.

What a termite barrier costs

Most chemical barrier and baiting systems on a Sydney home come in at around $5,000. A reticulation system on a new build is about $2,000. You get a written, itemised quote before anything starts.

After the install, a chemical barrier needs a yearly inspection ($330 single storey, $350 two storey) to keep the warranty valid. A monitoring system carries regular visits, usually about $1,500 to $2,000 a year.

The size of the house, the floor type and how much concrete there is against the walls all move the price. I can't price it properly without seeing it, so the quote comes after the inspection.

Start with an inspection

Every barrier job starts with a termite inspection. I check the house with a thermal camera and moisture meter, write the report on site on the AS 4349.3-2010 timber pest form, and hand it to you before I leave. Inspections are from $330 single storey or $350 two storey.

If the house needs a barrier, the report tells you why and the quote tells you what. Book a termite inspection.

Common questions

What is a termite barrier?
A treated zone of soil, a physical sheet and collars, or a set of pipes that stops termites getting from the soil into the house without being seen. It closes off the hidden ways in. It doesn't make a house termite-proof.

Which termite barrier suits an existing home?
It depends on the floor and how much of the ground around the house I can reach. A Termidor chemical barrier suits most existing homes. A monitoring system suits homes where a chemical barrier is hard to do properly, like pavers to the walls or water nearby.

Can I put a physical barrier under my existing house?
No. TermSeal and Green Zone sheeting go under the slab while the house is being built. For an existing home, the options are a chemical barrier or monitoring.

How long does a termite barrier last?
A Termidor chemical barrier carries my 8-year installation warranty, kept valid with a yearly inspection. TermSeal and Green Zone carry 50-year warranties, also kept valid with my yearly inspection. Reticulation lasts while it's refilled every 3 to 5 years and inspected yearly. Baiting is covered while it's monitored.

How much does a termite barrier cost in Sydney?
Most chemical barrier and baiting systems on a Sydney home come in at around $5,000. A reticulation system on a new build is about $2,000. You get a written, itemised quote before anything starts. After the install, a chemical barrier needs a yearly inspection ($330 single storey, $350 two storey), and a monitoring system usually costs about $1,500 to $2,000 a year in visits.