Concrete & Foundations
Termite Barrier Calculator
Calculates termite barrier length and rolls around a building perimeter (AS 3660)
Updated 26 June 2026 · Live
What this tool does
Calculates the length of termite barrier and the number of rolls needed around a building perimeter, with an allowance for laps and penetrations.
Formula Used
Spotted something off?
Calculations or display — let us know.
People also use
How the termite barrier calculator works
This calculator takes the building perimeter, adds 10% for laps and for working the barrier around penetrations, divides by the roll length, and rounds up to whole rolls. It applies to perimeter sheet and membrane barrier systems installed around a slab.
AS 3660 termite management
AS 3660.1 covers termite management for new buildings. A barrier is installed around the full perimeter and at every slab penetration — pipes, conduits and construction joints — because those are the paths concealed termites use. The standard recognises physical barriers, sheet/membrane systems and chemical-treated zones.
Perimeter and penetrations
Measure the slab perimeter the barrier follows. The 10% allowance covers laps between rolls and the extra material worked around pipe and conduit penetrations; on a slab with many penetrations you may need more.
What this tool does not do
It estimates barrier quantity only. It does not select the barrier type, design the penetration detailing, or certify the installation, which in most states must be carried out and documented by a licensed installer to AS 3660.1.
Adjusting the defaults
Every input is editable. Enter your own perimeter, roll length and price and the rolls and cost recalculate instantly.
On-site considerations
The weak points in any termite barrier are the penetrations and the laps, so order enough material to lap generously and to dress neatly around every pipe and conduit. Sheet and membrane barriers must be continuous and undamaged — a single gap gives concealed termites a path. In most states the installation has to be carried out and certified by a licensed installer and recorded on a durable notice in the meter box.
Using this alongside other BuildMetricLab tools
Pair this with the concrete slab, shed slab and damp proof course calculators when planning a slab-on-ground build. Every BuildMetricLab tool runs entirely in your browser — no sign-up, no data sent anywhere, and every formula is shown on-page so you can audit the maths.
Sources & methodology
Estimates termite barrier as the building perimeter plus 10% for laps and penetrations, divided by the roll length and rounded up to whole rolls. Every result is calculated from the values you enter, and all inputs are editable.
Frequently asked questions
Are termite barrier calculator results accurate enough to order materials?
Use them as a starting estimate only. Verifying the final quantity with your supplier or contractor before ordering is good practice — site conditions, wastage and cut-offs all affect the true figure.
What wastage percentage should I use?
The calculator defaults to the typical Australian trade allowance for masonry & brickwork. Increase it for complex cuts, awkward shapes, or first-time DIY. The default wastage allowance reflects common trade practice; values lower than the default may underestimate offcuts.
Does this replace professional advice?
No. This tool is a planning estimator. For works that affect structure, the National Construction Code (NCC), boundary or dividing-fence, gas, electrics, drainage to a sewer, or similar, consult a suitably qualified professional.
Can I change the unit prices?
Yes — every price field is editable. Plug in your supplier's quote to get a total that matches your project.
Related tools
Calculators from other categories that planners often reach for next.