California building code requires termite protection in new construction. Here's what pre-construction termite treatment involves, when it's required, what it costs, and why skipping it is a costly mistake.
What Is Pre-Construction Termite Treatment?
Pre-construction termite treatment — sometimes called a pre-treat or soil pre-treatment — applies termiticide to soil before a concrete slab is poured or before a structure's framing contacts the ground. The goal is to create a chemical barrier that prevents subterranean termites from entering through the foundation before the building is even complete.
In California, pre-construction termite treatment is required by Title 24 of the California Building Code in termite hazard zones, which covers most of Southern California including Orange County, Los Angeles County, the Inland Empire, and Riverside County.
When Is Pre-Construction Treatment Required?
California Building Code Section 2304.13 requires protection against subterranean termites for all new wood-framed construction in areas designated as having a "moderate to severe" or "very heavy" termite hazard. Southern California sits in the highest risk category.
Pre-treatment is typically required at the following stages:
- Before slab pour on slab-on-grade construction
- In sub-slab void fill and foundation gravel on post-tension slabs
- At perimeter soil around crawlspace foundations
- At soil contact points for wood posts, poles, and any below-grade wood members
The general contractor is responsible for ensuring treatment occurs before the relevant inspection phase. Most jurisdictions require documentation from a licensed structural pest control company as part of the building inspection record.
What Does Pre-Construction Treatment Involve?
The standard pre-construction treatment process includes:
1. Pre-slab soil treatment
Before the concrete slab is poured, the graded and compacted soil beneath the footprint is treated with a liquid termiticide. In California, commonly used products include Termidor (fipronil) and Biflex (bifenthrin). The chemical is applied at a specified rate per square foot, creating a treated zone that subterranean termite workers cannot penetrate without contacting a lethal dose.
2. Perimeter treatment
The soil around the foundation perimeter — typically 6 inches out from the foundation edge — is also treated. This creates a continuous barrier at soil level that deters foraging from established colonies in adjacent areas.
3. Wood treatment (optional but recommended)
Borate treatment applied to framing lumber before drywall installation provides long-lasting protection against both subterranean and drywood termites. Boracare penetrates wood fibers and remains active indefinitely, providing ongoing protection even if soil treatment degrades. Many builders include this as an upgrade.
4. Documentation
The treating company provides a certification document (sometimes called a Notice of Completion or a Subterranean Termite Pre-Construction Treatment Form) that is submitted to the building department or kept in the building permit file.
Why Pre-Construction Treatment Matters
The window for pre-construction treatment is the most cost-effective moment in a building's life to address subterranean termite risk. Here's why:
Access: Before a slab is poured, every square inch of the soil beneath the structure is accessible. Post-construction treatment requires drilling through concrete, injecting into void spaces, or installing bait stations — all more expensive and less comprehensive than treating open soil.
Cost: Pre-construction treatment for a new home in Southern California typically costs $400–$900, depending on square footage. The same subterranean termite treatment on an existing home can run $800–$2,000 or more due to access challenges.
Effectiveness: The treated barrier is most effective when applied to freshly graded, undisturbed soil — before irrigation, landscaping, and foot traffic degrade the treated zone.
Insurance / warranty: Many builders offer a structural warranty that is contingent on proper pre-construction treatment. Skipping or poorly documenting the treatment can void these warranties.
Pre-Construction vs. Post-Construction Treatment
| Factor | Pre-Construction | Post-Construction |
|---|---|---|
| Timing | Before slab pour or framing contact | After construction is complete |
| Soil access | Full — entire footprint treated | Limited — must drill/trench |
| Cost | $400–$900 | $800–$2,000+ |
| Disruption | None — integrated into construction schedule | May require moving plantings, cutting concrete |
| Effectiveness | Maximum — continuous barrier | Good, but gaps possible where access is limited |
| Code requirement | Required in Southern CA | Required for remodel additions in some jurisdictions |
Who Needs to Read This?
New home builders and general contractors: You are responsible for scheduling pre-construction treatment at the correct stage. Missed treatment discovered at inspection will delay your Certificate of Occupancy. We work with builders throughout Orange County, the Inland Empire, and Riverside County and can coordinate around your construction schedule.
New home buyers: If you're purchasing a newly built home, ask for the pre-construction termite treatment documentation. Verify that it was completed by a licensed pest control company (CA license required), that it covers the full footprint, and that it was applied at the correct stage. This documentation should be in your escrow file.
Homeowners adding additions or ADUs: Accessory dwelling units (ADUs) and room additions in Southern California may require pre-construction treatment under the same code sections as new construction, depending on the foundation type and jurisdiction. Confirm with your building department.
Pre-Construction Treatment in Southern California — Service Area
We provide pre-construction termite treatment for new construction, additions, and ADUs throughout:
- Orange County (all cities)
- Los Angeles County — South Bay, San Gabriel Valley, Long Beach area
- Inland Empire — San Bernardino County, Ontario, Riverside area
- Riverside County
Contact us for a pre-construction quote or call (714) 240-2800. We'll work around your construction timeline and provide all required documentation.
Related: Borate Treatment · Liquid Barrier (Termidor) · Free Termite Inspection