How to Read a WDO Inspection Report

Picture this: a homeowner just had a termite inspection. The next day, a 7-page PDF lands in their email. They open it, scroll past the cover page, and see this:

11B  PRICE: See 10A  (Section I)

They have no idea what that means. Neither does their realtor. Half the time, neither does the buyer's agent who ordered the inspection — not because they're incompetent, but because “See 10A” is standard shorthand on the California 43M-41 WDO inspection report, and nobody outside the industry carries a decoder ring.

I'm Ryan Berry. I'm a licensed Branch 3 pest control operator based in Orange County, California. I've written hundreds of 43M-41 reports. This article is my walkthrough of the code system — what every number and letter means, why the system was designed this way, and how the industry is starting to solve the readability problem that's been baked into this form for decades.

By the end, you'll be able to read any 43M-41 report cold: the codes, the section designations, the diagram, and the findings-to-recommendation chain that connects all of it.

Here's the honest thesis: the codes were designed to make inspectors' lives easier when they were filling out reports by hand in 1971. They make customers' lives harder in 2026. The industry has been stuck with the same confusing format for fifty years. That's starting to change — slowly.

A real WDO report, walked through

Let's start with a real example. The report below is one I wrote on November 13, 2025, for a single-family home in Yorba Linda, California. The customer name and exact address have been redacted; everything else is verbatim from the report I filed with the Structural Pest Control Board.

The property is a single-story wood-framed stucco residence with an attached two-car garage, a composition roof, and a detached patio structure at the rear. Standard Orange County residential. Here's the complete finding summary:

That's one normal day. One single-family home, eight finding codes spread across the main structure and a detached garage that couldn't be fully inspected. If you're the inspector, this is a clean report that took about 90 minutes on-site and another 15 to write up. If you're anyone else, the report is unreadable without a glossary. The diagram at the front of the report positions each code at its physical location on the property — 9A at the patio fascia, 10A at the side wall, 11A through 11D clustered at the rear, 8A at the garage access. The diagram makes spatial sense once you know what the codes mean. Before that, it's noise.

Why the codes exist

The 43M-41 is mandated by the California Structural Pest Control Board (SPCB) under Business and Professions Code Section 8516. Every licensed Branch 3 operator in California must use this form. You cannot legally substitute your own format, no matter how much clearer it might be.

The form has three classification tiers:

• Section I — Visible evidence of active infestation, infection, or damage directly caused by WDO activity. The inspector saw it. Section I findings are typically required to be addressed before escrow on a California real estate transaction can close. A Section I finding means the problem exists right now.
• Section II — Conditions likely to lead to infestation or infection, but no visible evidence of active damage yet. Earth-to-wood contact, inadequate subarea ventilation, irrigation hitting the foundation, a leaking shower pan. Section II findings are risk factors, not active problems — recommendations to prevent future damage, not requirements to fix existing damage.
• Further Inspection — Areas the inspector couldn't access. Not Section I or Section II — just “I couldn't inspect this; make it accessible and I'll return.” The 8A garage item on the report above is the canonical example.

The 43M-41 was last meaningfully revised in 1990. The SPCB updates the form periodically — format version numbers, disclaimer language, minor field adjustments — but the core structure of numbered zones and lettered findings dates to the 1970s. The system was designed for paper forms completed by hand. Writing “4A” is faster than writing “Finding A at the porch area.” At volume, that mattered.

The problem is that the shorthand only makes sense to people who write reports every day.

The number-letter code system, decoded

Here's the actual decoder ring.

The code on any 43M-41 finding consists of two parts: a number that identifies the property AREA where the finding was located, and a letter that identifies the sequence within that area. “10A” means the first (A) finding in the Interior area (10). “11B” means the second (B) finding in the Exterior area (11). The same code system shows up on the diagram at the front of the report — codes are positioned at the physical location of each finding so they can be cross-referenced against the findings text.

The number prefix — what type of finding it is

One clarification that trips up first-time report readers: the SAME finding code (e.g., “11A”) on two different reports could refer to two completely different findings, because the code reflects the property AREA where the finding was located, not the finding type itself. On one report 11A might be a drywood termite infestation; on another report 11A might be a dry rot finding. The number tells you WHERE on the property; the letter tells you which finding in that area. Always read the full finding description, not just the code.

The letter suffix — sequence and type

The letter is primarily sequential — it tells you which finding number this is within a given property area. Many inspectors follow rough conventions (A is active, C is past damage, D is dry rot), but these conventions vary by operator and shop. The letter doesn't carry a fixed categorical meaning the way the number does; it just tells you the order. Always read the full finding description to understand what was actually observed. Now let's walk through the report we read above:

• 10A = First finding in the Interior area. In this case, an active drywood termite infestation at the plumbing trap access. Treatment: fumigation (primary) or localized Termidor (secondary, substandard).
• 11A = First finding in the Exterior area. Active drywood termite infestation at rafter tails, rear of house. Price: included in 10A fumigation.
• 11B = Second finding in the Exterior area. Active drywood termite infestation at sheathing and additional rafter tails. Also included in 10A.
• 11C = Third finding in the Exterior area. Termite damage at sheathing and rafter tails — visible damage from termite activity. Requires wood replacement (separate scope from treatment). Included in 9A.
• 11D = Fourth finding in the Exterior area. Dry rot damage at sheathing from moisture and fungal decay. Included in 9A.
• 9A = First finding in the Decks & Patios area. Dry rot damage at fascia and rafter on the patio side of the house. Includes the wood replacement work covered under “See 9A” pricing for related findings.

Now you can read any 43M-41 report. The next time you see “11B PRICE: See 10A” on a report, you know exactly what it means: a second cluster of active drywood termite findings on the exterior, priced into the whole-structure fumigation already listed at 10A. It's not a typo. It's not missing information. It's the standard shorthand for a treatment that covers multiple finding codes on the same structure simultaneously.

The honest take: this system is confusing

Here's the part nobody in the industry says out loud.

The 43M-41 was designed to make life easier for inspectors filling out reports by hand in the 1970s. Numbers and letters write faster than full sentences. “10A” is two characters. “Active drywood termite infestation found at the plumbing trap access panel, interior” is nineteen words. When you're writing four to eight reports a day on a paper form, the shorthand is a gift.

The form serves a regulatory purpose first. It's filed with the SPCB. It is a legal document for regulators, courts, and escrow agents. The customer's ability to understand it was not the primary design criterion. That was a reasonable design decision in 1975. It is a worse decision with every passing year.

In 2026, customers receive these reports as PDFs in email. They open them on a phone. They scroll through seven pages of regulatory language, zoom into a diagram, and find a findings section where every entry is a code-price-section triplet that references other entries. They have to flip back and forth between the diagram and the findings text to figure out what “11B at Rafter Tails and Sheathing” means.

Real estate agents who handle five to ten WDO reports a week develop a working vocabulary. They know what Section I means. They know that “See 10A” means fumigation covers it. They function — but they shouldn't have to maintain a mental glossary just to read a document their clients received in writing.

Homeowners reading their own report often call the inspector: “What does 10A mean?” Every working Branch 3 inspector has fielded this call dozens of times. I have. It's a ten-minute conversation that happens after every complex report. It's a recurring cost of the current design that nobody talks about because it's assumed as normal overhead.

The system isn't broken because inspectors are bad at communicating. The system is broken because the form was built for a different era and a different primary audience. Regulatory consistency requirements, industry inertia, and the genuine difficulty of changing a legally prescribed document used by tens of thousands of operators statewide have kept it frozen.

This isn't a knock on the SPCB. The agency has a genuinely hard job balancing regulatory consistency, industry compatibility, and consumer protection. The format does what it was designed to do. But the customer-facing experience is a UX problem the industry has acknowledged for decades, and it's becoming harder to ignore as software starts to make it solvable without changing the underlying form.

How modern WDO software handles this

The code-to-plain-language translation problem is a software problem. It was an unsolvable paper problem. It's a solved software problem — if the software is built to solve it.

When an inspector selects “10A” in modern WDO software, the platform pre-populates the findings text: “Active drywood termite infestation found at [location]. Recommended treatment: fumigation with Vikane or Zythor Gas (primary), OR localized chemical treatment with Termidor (secondary — substandard measure under Business and Professions Code Section 1992).” The inspector fills in the specific location. Everything else is pre-written, pre-reviewed, SPCB-compliant language. No retyping the same recommendation a hundred times a year.

The customer-facing report can show both layers simultaneously: the regulatory code (which the SPCB requires) and the plain-language explanation (which the customer can actually read). The document filed with the SPCB looks the way the SPCB expects. The PDF the customer receives in email includes a plain-language interpretation: “What this means: We found active drywood termites inside the structure at the plumbing access area. Our primary recommendation is whole-structure fumigation, which also covers the exterior findings listed as 11A and 11B.” No phone call required.

Inspectors benefit on time — every code pre-fills its standard recommendation, confirmed for location and price. Customers receive reports they can actually read. The SPCB still receives the format they require.

This is what Bug HQ does. I built the platform around my own working inspector experience — ten years of fielding “what does this code mean?” phone calls. Bug HQ's findings library maps every standard 43M-41 code to pre-written, SPCB-compliant plain-language findings and recommendations. Inspectors select findings from a structured menu. Customers receive reports written in both regulatory code and plain English.

If you're an operator and the code-glossing problem resonates, Bug HQ was built specifically for this.

Common mistakes operators make on a 43M-41

Four mistakes I've seen — and made — over ten years of writing reports:

• Missing a finding. The single most damaging mistake. A finding the inspector missed on the original inspection becomes a problem when escrow closes and the buyer discovers it themselves. The customer loses trust, the escrow officer flags the report, and the inspector has to issue a supplemental report — often without being able to charge for the additional work. In liability terms, this is the one that costs operators the most. The cure is a consistent inspection checklist followed in the same order on every job, not relying on memory.
• Forgetting to sign the report. The report is not legally valid without the inspector's signature and license number. SPCB audits routinely catch unsigned reports. A violation against the operator's license can result even when every other field is correct. With paper forms, this happened regularly. Modern WDO software can require signature before the report is finalized.
• Forgetting to check the attic. The attic is the most common location for drywood termite activity in California, and the most commonly skipped inspection area when access is awkward or it's a hot day. A WDO report that doesn't address the attic is incomplete by definition. Either inspect it or document it as inaccessible via Further Inspection — never silently omit it. The SPCB requires every accessible area to be accounted for.
• Sending the report to the wrong customer. When you run multiple inspections per day, mixing up the email send is easy. The wrong customer now has someone else's property report (a privacy issue), and your customer doesn't have theirs (a service issue). Modern WDO software attaches reports directly to the customer record so this can't happen. On paper or manual email, it's distressingly common.

The first three are mistakes about the inspection itself. The fourth is a process problem that software solves. The first three are a culture problem that experienced inspectors solve.

Quick reference: WDO report codes FAQ

What does Section I mean on a WDO report?

Section I findings are visible evidence of active infestation, infection, or damage directly caused by WDO activity. The inspector saw it on the day of the inspection. Section I work is typically required to clear escrow on a California real estate transaction.

What does Section II mean on a WDO report?

Section II findings are conditions that could lead to future infestation or damage, but the inspector didn't see active damage on the day of the inspection. Section II items are recommendations to prevent future problems, not requirements to address existing ones.

What does “Further Inspection” mean on a WDO report?

An area the inspector couldn't access — storage was blocking it, an attic hatch was locked, or the area was otherwise physically inaccessible. Not Section I or Section II. The inspector will return to inspect it once access is provided. It doesn't mean the area is clear; it means the inspector couldn't look.

What is the 43M-41 form?

The standard wood-destroying organism inspection report form required by the California Structural Pest Control Board (SPCB) under Business and Professions Code Section 8516. Every Branch 3 operator in California must use this format for every WDO inspection.

What does 1A mean on a termite report?

Subterranean termite finding, first instance, active. Treatment is typically soil injection of Termidor (fipronil) at the soil-wood contact line around the perimeter of the structure.

What does 10A mean on a termite report?

Drywood termite infestation, interior, first finding, active. Treatment is typically whole-structure fumigation with Vikane (sulfuryl fluoride) or Zythor Gas, or localized chemical treatment with Termidor for individual findings.

What does 11B mean on a termite report?

Drywood termite infestation, exterior, second finding or multiple instances at the same general exterior location. Typically covered under the same fumigation recommendation as 11A and any interior drywood termite findings on the same structure.

How do I read the diagram on a WDO report?

The diagram shows the property layout viewed from above, with finding codes marked at each finding's physical location. Numbers indicate the finding type, letters indicate sequence within that type. Each code on the diagram corresponds to a finding entry in the body of the report. North is typically indicated. Codes on the diagram must match codes in the findings text — mismatches are a common SPCB citation.