Termite Chemical Barrier and Foam Calculator
A chemical termite barrier needs a set volume of mixed termiticide for every cubic metre of soil in a vertical zone and every square metre of a horizontal zone. At 100 L of mix per cubic metre, the rate the labels we read use for a trench, a trench 150 mm wide and 350 mm deep takes 5.25 L per metre. Add each part of the job below (a trench, rodding under concrete, a soil surface, holes through a slab or foam) with the rates from your label. You get the litres for each part, the total, the product and the tank fills, and a summary for your records.
For licensed pest managers. The label always wins. Termiticides are applied by licensed pest managers, following the product label and the AS 3660 series. This page gives no product rates: you type the rate and the mix from your own label, and the calculator does the arithmetic.
Free tool
Work out the litres for the job
Add each part of the job and type the rate from your label. You get the litres of mix for each part and in total, the product, tank fills and foam.
A trench 150 mm wide and 350 mm deep at 100 L of mix per cubic metre of soil takes 5.25 L per metre. The calculator needs JavaScript; the worked examples and tables below work without it.
Next steps
- Foaming cavities and voids? See our termiticide foam injectors and sprayers and the termite foam injection guide.
- Water based and solvent carried termiticides need different seals. Check yours in the Chemical Compatibility Guide, or send us the SDS.
- Mixing a small batch for a hand sprayer? Use the Dilution Calculator.
A guide only, for licensed pest managers. The product label comes first: follow its rates, mixing, application and safety directions, and the AS 3660 series. Measure the job on site and check every figure against the label.
How the calculator works out each part
- Trench and treat (vertical zone): litres per metre = width × depth (both in metres) × the label rate in litres per cubic metre of soil. For example 0.15 × 0.35 × 100 = 5.25 L per metre.
- Rodding under concrete (vertical zone): holes = length ÷ hole spacing, rounded up. Litres per hole = width × depth × spacing (all in metres) × the label rate. If your label gives litres per metre or per hole, enter that instead.
- Spraying the soil surface (horizontal zone): litres = area in m² × the label rate in litres per m².
- Drilling and injecting through a slab (horizontal zone): holes per m² = 1 ÷ the spacing in metres, squared. Litres per hole = the label rate per m² × the spacing squared, or the label’s own figure per hole.
- Foam: litres of foam = litres of mix × the expansion ratio. A void of length (m) × height or width (m) × depth (mm) holds that many litres, so the mix to fill it is that volume ÷ the expansion ratio.
- Product: litres of mix × the amount of product on the label ÷ the litres of water it goes in.
- Tank fills: litres of mix ÷ the tank size, rounded up.
Every figure is rounded up, so the calculator never shows less than the arithmetic gives. The labels we read say do not apply at less than label rates.
Worked examples
- Trench along a house wall: 30 m of trench 150 mm wide and 350 mm deep, at a label rate of 100 L per m³, is 5.25 L per metre and 157.5 L of mix.
- Rodding under a path: 6 m of path with holes 200 mm apart, treating a zone 150 mm wide and 350 mm deep at 200 L per m³ (the labels we read double the volume under concrete), is 30 holes of 2.1 L, 63 L of mix.
- Drilling a bathroom slab: 4 m² with holes 200 mm apart at 10 L per m² is 100 holes of 0.4 L, 40 L of mix. With holes 150 mm apart the same floor takes 178 holes of 0.225 L.
- Foam under a slab where the soil has dropped away: a gap 2 m long, 1.5 m wide and 40 mm deep holds 120 L of foam. At 10:1 that is 12 L of mix. At a label rate of 10 L per m², the 3 m² needs 30 L, so the labels say to apply the other 18 L as liquid.
Example only, not a rate for any product: if a label said 400 mL in 100 L of water, the 260.5 L for the first three examples would take 1,042 mL (1.042 L) of product. In a 100 L tank that is 3 fills: 2 full fills with 400 mL each and a last fill of 60.5 L with 242 mL.
Vertical and horizontal zones: what the labels say
| Part | What the labels we read say |
|---|---|
| Trench (vertical zone) | At least 100 L of mix per m³ of soil. At least 150 mm wide, down to 50 mm below the top of the footing (80 mm on Biflex AquaMax). Trenching and treating the backfill is the preferred way. |
| Rodding under concrete (vertical zone) | 200 L per m³ of soil (Termidor Residual, Altriset). Holes no more than 200 mm apart (Termidor Residual) or 300 mm (Altriset). Rod only where trenching and treating the backfill is not possible or practical. |
| Soil surface (horizontal zone) | 5 L per m², at least 80 mm deep. Not below 3 L per m² (Termidor Residual, Altriset) or 2 L per m² (Biflex AquaMax), with a stronger mix where less water is used. |
| Through a slab (horizontal zone) | Up to 10 L per m² (Termidor Residual, Altriset). Holes 150 to 300 mm apart and no more than 150 mm from walls, cracks, expansion joints and service penetrations. |
| Foam | Adds to the liquid where it cannot reach, such as voids under a slab. The foam must carry the label rate; if it cannot, apply the rest as liquid. Not a stand alone treatment. |
Sources: the current APVMA approved labels for Termidor Residual (54624/142387) and Altriset (64594/109049), and the Biflex AquaMax label (60678/0109). Other termiticides set their own rates: read yours. The labels say any change to the trench or rodding sizes must be worked out again from the volume per cubic metre, which is what the calculator does.
Hole spacing and litres per hole
Litres per hole for a slab at 10 L per m², and for rodding a zone 150 mm wide and 350 mm deep at 200 L per m³:
| Spacing | Holes per m² | Slab, L per hole | Rodding, L per hole |
|---|---|---|---|
| 150 mm | 44.4 | 0.225 | 1.58 |
| 200 mm | 25 | 0.4 | 2.1 |
| 250 mm | 16 | 0.625 | 2.63 |
| 300 mm | 11.1 | 0.9 | 3.15 |
Holes per m² is 1 ÷ the spacing in metres, squared, which matches the Altriset slab table (44, 25, 16 and 11 holes). The labels round their rodding tables to 10 L per metre (1.5, 2, 2.5 and 3 L per hole when injecting to a depth of 300 mm) and say any other size must be worked out again at 200 L per m³. One label lists 36 holes per m² and 0.3 L per hole at 150 mm, which is more than 10 L per m². Where your label lists a volume per hole for your spacing, choose L per hole in the calculator and enter the label’s figure.
Foam: expansion ratio and litres of mix
The expansion ratio is the volume of foam divided by the volume of liquid. At 15:1, 1 L of mix makes 15 L of foam. For a horizontal zone, the labels’ foam tables give the finished foam for each square metre (they list 5:1, 10:1 and 25:1):
| Mix per m² | 5:1 | 10:1 | 15:1 | 20:1 | 25:1 |
|---|---|---|---|---|---|
| 5 L | 25 L | 50 L | 75 L | 100 L | 125 L |
| 10 L | 50 L | 100 L | 150 L | 200 L | 250 L |
For wall cavities, the Termidor Residual label says to foam to 15:1 and only where live termites are present, and the Altriset label recommends a dry foam of 20:1 behind plasterboard. A 90 mm stud cavity 450 mm wide holds about 40.5 L of foam per metre of height, which is 2.7 L of mix at 15:1. The labels say foam is not a stand alone treatment: follow it with a continuous soil treatment as per AS 3660.2.
Dry foam climbs and clings; wet foam collapses and drains. More in our termite foam injection guide. Our pest and termite control range includes Termifoam injectors from a 1.2 L hand unit to a 12 L air driven unit.
Mixing to the label rate
Product = litres of mix × the amount of product on the label ÷ the litres of water it goes in. The labels we read say to half fill the tank with water, add the product, then top up to the volume you need, so the calculator treats the label’s amount in 100 L of water as product made up to 100 L of mix. Follow your label’s mixing steps.
Where the soil will not take the full volume, some labels allow less water per m² or m³ with a stronger mix, so the same amount of product goes on each square or cubic metre. Enter the reduced volume and the stronger mix exactly as your label’s table gives them, and use one mix per calculation.
For a small batch in a hand sprayer, the Dilution Calculator turns a label rate into millilitres for any tank. Water based and solvent carried termiticides differ, so check your sprayer or foamer seals in the Chemical Compatibility Guide, or send us the SDS and we will confirm.
What to record
AEPMA’s notes on AS 3660.2:2017 say the certificate of installation “needs full details of products and volumes”, the durable notice needs the chemical type and dilution for reapplication, and certification records are kept for 10 years. In Queensland, pest management records for timber pests include the application rate. Check the rules for your state and your licence.
The calculator’s job summary lists each part with its size, rate and litres, then the total, the product and the tank fills. Tap Copy job summary and paste it into your job record, or print it.
Frequently asked questions
How much termiticide do I need per metre of trench?
At 100 L of mix per cubic metre of soil, a trench 150 mm wide and 350 mm deep takes 5.25 L per metre. For other sizes, multiply the width by the depth in metres and by the rate on your label.
How do I work out termiticide for rodding under a path?
Holes = length ÷ hole spacing, rounded up. Litres per hole = width × depth × spacing in metres × the label rate. At 200 L per m³, a zone 150 mm wide and 350 mm deep with holes 200 mm apart takes 2.1 L per hole.
How many holes per square metre when drilling a slab?
One divided by the spacing in metres, squared: about 44 at 150 mm, 25 at 200 mm, 16 at 250 mm and 11 at 300 mm. At 10 L per m² that is 0.225 L, 0.4 L, 0.625 L and 0.9 L per hole.
What is a chemical termite barrier?
A continuous zone of soil treated with a registered termiticide, under and around a building, that deters termites from getting in unseen. The labels and the AS 3660 series call it a chemical soil treated zone: vertical zones along walls and footings, and horizontal zones under floors and slabs.
What is a foam expansion ratio?
The volume of foam divided by the volume of liquid. At 15:1, 1 L of mix makes 15 L of foam. A drier foam has a higher ratio.
How much termiticide mix makes a litre of foam?
One litre divided by the expansion ratio: about 67 mL of mix at 15:1, 50 mL at 20:1 and 33 mL at 30:1.
Is Termidor Foam the same as foaming Termidor Residual?
No. Termidor Foam is a ready to use can: its label says it makes a dry foam of about 30:1, with 30 g giving about 1 L of foam. Termidor Residual is a concentrate you mix with water and a foaming agent in a foamer, to the ratio its label gives (15:1 for wall cavities). This calculator is for foam made in a foamer.
How wide and deep should a termite trench be?
The labels we read ask for at least 150 mm wide, down to at least 50 mm below the top of the footing (80 mm on Biflex AquaMax). Follow your label and AS 3660.2.
Can I use less water when the soil will not take 5 L per m²?
Some labels allow less water per square metre with a stronger mix, so the same amount of product goes on. They say not to go below 3 L per m², and one says 2 L. Enter the volume and the mix from your label’s table.
Does this calculator give termiticide rates?
No. It never supplies a rate. You type the rate and the mix from your product label, and it does the arithmetic. The label and the AS 3660 series always come first.