Pre-construction termite control is the cheapest and most effective way to protect a building. After the pour, reaching the soil under the foundations is hard and costly; before it, a continuous chemical barrier can be laid under the whole building.
Why treat before building?
- Subterranean termites live in soil and reach buildings through small tunnels from the foundations.
- After construction you need drilling and injection in tight places that may not reach every point.
- Pre-treatment covers the soil under floors and foundations at once and costs less than later remediation.
Stages of pre-treatment
1. Site preparation
- Remove tree roots, timber scraps and debris from the soil.
- Remove any visible nests or tunnels.
- Level the soil so the solution spreads evenly.
2. Treating soil under the slab
- An approved termiticide solution is applied to the soil surface before the floor is poured to form a barrier layer.
- Pay attention to pipe penetrations, openings and joints.
3. Foundations and retaining walls
- Treat the foundation trench on both sides before backfilling.
- Treat the backfilled soil along walls, and again after backfilling where needed.
4. Perimeter barrier
- An external barrier around the perimeter protects against approach after completion.
- Cover pipe entries and electricity and water meter points.
5. Protecting timber
- Use treated timber for doors, roofs and frames as designed.
- Separate timber from soil and do not bury it in backfill.
Practical timing of treatment before the pour
Treatment is carried out after excavation and soil levelling are finished and the floor services are placed, and immediately before the concrete is poured. If heavy rain falls after treatment and before the pour, or later works disturb the treated soil, the affected parts need to be treated again. The aim is a continuous barrier under the building with no gaps.
Spots where the barrier is often missed and termites get through
- Around pipes that pass through the floor, such as drainage and electrical conduits.
- Expansion joints between concrete sections.
- Around columns and their bases and beneath load-bearing walls.
- Beneath door thresholds and external openings.
- The outer edges of the building and the foundation edges.
The external perimeter barrier after construction
The barrier under the building is completed with an external barrier around the foundations that prevents entry from the neighbouring soil. It helps to keep a dry gap between the wall and any timber or plants, drain water away from the foundation, and avoid stacking timber and wooden waste near the building.
Common mistakes
- Treating after the pour instead of before, so not all soil is reached.
- Ignoring gaps around pipes and joints.
- Leaving timber scraps in the soil before backfilling.
- Moisture and water leaks near foundations.
- No documentation or warranty from the contractor.
How to choose a soil termiticide before building
- Choose a product made for termites and soil treatment, whose label lists use before construction.
- Check the active ingredient and the form: a liquid concentrate sprayed onto soil, or a dust used as the label directs.
- Non-repellent products let termites pass through treated soil, so the active ingredient is carried within the colony.
- Work out the volume of solution from the soil area first, then buy the containers, so you do not run short mid-job.
- Prepare a sprayer or pump suited to the area so the solution is spread evenly over every part.
Orkida products for pre-construction termite treatment
- Premise 200 SC (Envu): imidacloprid 20%, non-repellent and odourless, with long-term protection as the label states.
- Bayflex TC (FMC): bifenthrin 25% emulsifiable concentrate, used before building as a soil spray and afterwards by injection.
- Waja Plus 0.5 DP: fipronil 0.5% dust (10 kg pack) for soil treatment before building as the label directs.
For existing homes with a recent infestation see the home termite control package, and browse the whole termite insecticides before and after building section. Read each product label for dilution and application before use.
After handover
- Leave a gap between planted soil and the wall.
- Fix leaks immediately, since moisture attracts termites.
- Inspect periodically, especially timber and corners. See signs of termites and preventing termites.
- For existing buildings read eliminating termites: chemical barrier and spot treatment.
To identify the type read termites: the complete guide, and browse termite control.
FAQ
Does pre-treatment replace later inspection?
No. It greatly reduces risk but periodic inspection is essential, and the barrier weakens over time.
Is treating timber alone enough?
No. Subterranean termites arrive through soil and foundations, so soil treatment is needed.
Can treatment be done after the pour?
Yes, by drilling and injection, but it is harder, costlier and less complete.
Summary
Pre-construction treatment is a continuous barrier under the building. Do it before the pour with a licensed company, with documentation and warranty, then keep moisture away and inspect periodically.