Is there one standard set of termite diagram codes?

No. Texas specifies codes and symbols in the instructions to its official WDI form, but in California and most other states each company maintains its own code book (a legend of abbreviations). What is standard is the requirement that the diagram legibly show where each finding is, and that any abbreviations used are explained in a legend on the report.

What do the letter codes on a Texas WDI diagram mean?

The Texas SPCS/T-5 instructions assign letters to insect types and findings, such as S for subterranean termites, D for drywood termites, and F for Formosan termites, with markings distinguishing active infestation from previous infestation. Conducive conditions get their own letters, for example G for wood-to-ground contact. The exact list is printed in the form's instructions, so the reader of any Texas report can decode the diagram the same way.

How are findings marked on a California WDO diagram?

Common practice is to key the diagram to the report's numbered findings: each finding in the report (1A, 1B, 2A...) is written on the diagram at the location where it was observed, so the reader can move between the findings list and the drawing. Many companies also use two- or three-letter codes from their own code book, with a legend on the report explaining each one.

Does the diagram have to look like the actual building?

Yes, within reason. Texas requires the diagram to resemble the structure with approximate perimeter measurements on all sides. California expects the diagram to reasonably represent the structure inspected, with findings shown in their approximate locations. A generic rectangle with codes floating in it invites questions from buyers, agents, and regulators.

Why do companies keep a code book at all?

Consistency and speed. When every inspector uses the same abbreviation for cellulose debris, the office can assemble reports without decoding each tech's personal shorthand, re-inspections are comparable to the original, and new hires learn one legend instead of five. The code book doubles as a training document.

Can Serv AI draw the diagram and place the codes?

Yes. Serv AI imports the building footprint by address to start the diagram, and inspectors place findings on it from their phone. Companies load their own code book, so the codes on the diagram match the legend on the report automatically, and the numbered findings stay in sync between the diagram and the write-up.

Termite Inspection Diagram Codes and Symbols, Explained

Why diagrams carry codes

Both the Texas WDI report and the California WDO report require a diagram of every structure inspected. The diagram's job is to answer where: where the live termites were found, where the moisture damage is, which corner of the garage has earth-wood contact. Writing full sentences on a small drawing does not work, so findings are marked with short codes placed at the location where they were observed, and a legend explains what each code means.

The important thing to know up front: there is no single national code standard. Texas prints its codes in the official form instructions. California and most other states leave the abbreviations to the inspection company, and require the report to explain them.

Texas: codes fixed by the form

The instructions to the Texas SPCS/T-5 form assign the markings, so every Texas WDI diagram can be read the same way. Insect types get letters (S for subterranean termites, D for drywood, F for Formosan), with the markings distinguishing active infestation from evidence of previous infestation. Conducive conditions are marked with their own letters, for example G for wood-to-ground contact, placed on the diagram where the condition exists. The diagram itself must resemble the structure and include approximate perimeter measurements on all sides.

For the full section-by-section breakdown, see our Texas WDI report guide.

California: numbered findings plus a company code book

California WDO reports list findings as numbered items, classified into Section 1 and Section 2. The usual practice is to key the diagram to those item numbers: finding 1A in the report appears as "1A" on the diagram at the spot where it was observed, so a reader can move between the findings list and the drawing without guessing.

On top of the item numbers, most companies use their own abbreviations from an internal code book. The codes below are typical, but every company's legend is its own:

Code	Typical meaning
ST	Subterranean termites
DT / DW	Drywood termites
FD / DR	Fungus / dry rot damage
EM	Excessive moisture
CD	Cellulose debris (wood scraps under the structure)
EWC	Earth-wood contact
FG	Faulty grade (soil level above the foundation line)
IA	Inaccessible area
FI	Further inspection recommended

Representative examples only. Always read the legend printed on the specific report in front of you.

The legend is not optional

Wherever abbreviations appear on a diagram, the report needs a legend explaining them. Some states write this into regulation explicitly; everywhere, an unexplained code is a finding the buyer, agent, or regulator cannot verify. If a re-inspection or a complaint lands on your report two years later, the legend is what makes the diagram defensible.

Keeping codes consistent across a crew

The failure mode is not a missing code, it is five inspectors with five personal shorthands. Then the office decodes each tech's habits, re-inspections stop matching the original report, and training a new hire means teaching them everyone's dialect. A written company code book, one legend used by everyone, fixes it, and doubles as the training document.

Diagrams with your codes built in

Serv AI starts the diagram from the building's actual footprint, imported by address. Inspectors drop findings on it from a phone, using your company's own code book, and the diagram, legend, and numbered findings stay in sync on the finished report.

Termite inspection diagram codes and symbols, explained