Termite Inspection in San Antonio Before Buying a Home: What You Need to Know

In Texas, a pre-purchase termite inspection is officially called a Wood Destroying Insect (WDI) or Wood Destroying Organism (WDO) inspection. The inspector covers all accessible areas of the structure, looking for termites, carpenter ants, and powder post beetles. It is a visual inspection limited to what is accessible. Inspectors cannot open walls or move furniture, which is why findings about conducive conditions matter as much as active evidence.

A Texas WDI report documents findings in three categories: evidence of active infestation, evidence of previous infestation, and conditions conducive to infestation. Conducive conditions are particularly important in San Antonio homes because they indicate where future termite activity is likely even if no live termites are present at the time of inspection. Common conducive conditions include wood-to-soil contact on fence posts or deck beams, foam board insulation below grade that provides a protected entry tunnel, and foam spray insulation on foundation walls that hides mud tube activity.

Subterranean termites in Texas live in soil-based colonies that can number in the hundreds of thousands to millions of workers. They require contact with soil moisture to survive and build mud tubes (pencil-width tunnels of soil and saliva) to travel from their underground colony to above-ground wood sources while maintaining moisture. Finding mud tubes on a foundation wall is one of the most definitive signs of active subterranean termite activity.

Colonies swarm (produce winged reproductives) in San Antonio primarily in spring, typically March through May, after the first warm rain events. Homeowners who see swarms of small winged insects inside their home or around windows and door frames in spring should have a WDI inspection promptly. Swarmers are not themselves destructive, but their presence indicates a mature colony is established nearby or inside the structure.

Not all WDI inspection findings are equal. Finding conducive conditions is common and does not necessarily indicate termite damage. Finding evidence of a previous infestation that was treated and has no active evidence is more serious but may be acceptable if the existing treatment is current and under warranty. Finding active live termites or recent active damage is a negotiation point that should be addressed before closing.

In Texas real estate transactions, buyers commonly negotiate for the seller to provide treatment or a treatment credit when active termites are found. However, treatment does not undo existing structural damage. If the inspection report notes significant wood damage in structural members, a separate structural evaluation by a licensed engineer may be warranted before proceeding.

Two primary treatment approaches are used for subterranean termites in Bexar County: liquid soil barrier treatment and bait systems. Liquid treatment involves applying a termiticide into the soil around and under the foundation to create a treated zone that terminates or repels foraging termites. This approach provides immediate action but requires drilling through concrete and careful application. Most liquid termiticides used today are non-repellent products that are slow-acting and can be spread through the colony.

Bait systems place termite bait stations around the perimeter of the structure. Foraging workers find the bait, recruit other workers, and carry the active ingredient back to the colony. Bait systems require regular monitoring and are effective but slower to achieve full colony elimination than liquid treatment. Some properties use both approaches, particularly those with heavy clay soils that limit liquid penetration or existing moisture management problems.

A one-time termite treatment does not protect a home permanently. Liquid termiticide barriers break down over time, and soil disturbance from landscaping, irrigation, and foundation settling can create gaps. Most treatment warranties require annual inspections to remain valid, and annual inspections are the correct standard for any San Antonio home regardless of treatment history.

For homes with existing bait systems from a prior owner or treatment company, ask for the monitoring records before purchasing. Systems that have gone uninspected for a year or more may have expired bait, damaged stations, or new activity that has not been detected. Continuity of monitoring is a core part of the bait system's effectiveness.