1.4 Wood Infestation Reports (CL-100) & Structural Pest Regulations
Key Takeaways
- The Official South Carolina Wood Infestation Report (Form CL-100) is a legally regulated real-estate disclosure of visible wood-destroying organism evidence — an investigative inspection report, not a "clear letter," structural engineering warranty, or whole-house guarantee.
- Regulation 27-1085 sets no expiration date for a CL-100; the widely used 30-day window is a lender, VA/FHA, and closing-attorney requirement that the report be dated within 30 days of closing, and a delayed closing therefore usually forces a re-inspection.
- Under SC Regulation 27-1085 K(3)(f), the inspection for wood-decaying fungi and decay damage is limited to the area below the level of the first main living-area floor — but decay damage in the lower portions of exterior doors, door jambs and frames, steps, stairs, and porch columns must still be reported.
- A wood moisture meter reading of 20% or higher indicates conditions conducive to wood-decay fungi, while readings of 28% or higher indicate active decay fungi infestation.
- A CL-100 may only be issued by an individual currently licensed in Category 7A who is covered under a valid Pest Control Business License, and the report must be signed, dated, and carry both the applicator and business license numbers.
Wood Infestation Reports (CL-100) & Structural Pest Regulations
In South Carolina, structural pest control is subject to some of the most rigorous regulatory standards in the nation due to the state's warm, humid subtropical climate, which creates ideal environmental conditions for subterranean termites, wood-boring beetles, and wood-decaying fungi.
Central to structural pest regulation is the Official South Carolina Wood Infestation Report (Form CL-100), commonly referred to in the real estate and mortgage industries as the "termite letter" or "CL-100."
1. Legal Authority & Purpose of the CL-100 Report
The Form CL-100 is governed by SC Regulation 27-1085 K. It is an official document required by mortgage lenders, title companies, and real estate buyers during property transfers in South Carolina to disclose visible evidence of active or past infestations of wood-destroying organisms (WDO). Under 27-1085 K(1), a wood infestation report issued in connection with a sale or mortgage may only be issued by an individual currently licensed in Category 7A who is covered under a valid Pest Control Business License; the report must be signed and dated by that individual and must show both their applicator license number and business license number. The inspection must be reported on the most current Official South Carolina Wood Infestation Report Form published by the Department, and the licensee furnishes the form.
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| THE SOUTH CAROLINA FORM CL-100 |
| |
| [LEGAL STATUTE] ---> SC Regulation 27-1085 K |
| [PRIMARY PURPOSE] ---> Disclosure of visible WDO evidence in real estate|
| [DATING WINDOW] ---> No expiration in the regulation; lenders and |
| closing attorneys require a report dated within |
| 30 days of closing |
| [LICENSED ISSUER] ---> Individual currently licensed in Category 7A AND |
| covered under a valid Pest Control Business |
| License; signed, dated, applicator + business |
| license numbers shown |
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[!NOTE] The Myth of the "Clear Letter": A widespread misconception among real estate agents and homeowners is that the CL-100 must be a "clear letter" indicating zero defects. Legally, the CL-100 is an investigative disclosure report. The inspector's statutory duty is to report all visible findings truthfully and accurately, whether or not active infestation or previous damage is found. An inspector who conceals past termite damage to deliver a "clean" report commits a severe regulatory violation punishable by license revocation and civil penalties.
2. Inspection Scope & Time Validity
Inspectors executing a CL-100 must adhere strictly to defined spatial and chronological boundaries established by Clemson DPR regulations.
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| CL-100 INSPECTION SCOPE BOUNDARIES |
| |
| [STRUCTURE EXTERIOR] ---> Foundation perimeter, siding, mulch lines, |
| masonry veneer, porches, earth-to-wood contact |
| |
| [STRUCTURE INTERIOR] ---> Accessible baseboards, door frames, plumbing |
| traps, window sills (readily visible areas) |
| |
| [CRAWLSPACE / SILLS] ---> Foundation walls, piers, sills, floor joists, |
| subfloors (MANDATORY FOR WOOD-DECAY FUNGI) |
| |
| [EXCLUDED / LIMITS] ---> Inaccessible wall cavities, finished ceilings, |
| areas blocked by stored goods/insulation |
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Critical Inspection Parameters:
- The 30-Day Window — Know Its Real Source: Regulation 27-1085 does not assign an expiration date to a CL-100. The familiar 30-day rule is a lending and closing requirement: mortgage lenders, VA and FHA underwriters, title companies, and closing attorneys generally will not accept a wood infestation report dated more than 30 days before closing, because moisture conditions and infestation activity can change quickly. The practical effect is the same — if a closing slips past the 30-day mark, the buyer pays for a new inspection — but on the exam, attribute the window to lender practice, not to a DPR expiration rule.
- Accessible Areas Only: The inspection is visual and non-destructive, restricted to readily accessible areas. Inaccessible locations (such as wall voids, areas behind fixed wall coverings, or subfloors obstructed by heavy insulation) must be explicitly listed on the report as uninspected / inaccessible areas. Regulation 27-1085 K(3) sets the minimum scope: a visual inspection of all accessible interior and exterior portions including crawlspaces, utility areas, and attics; careful sounding and probing wherever damage is visible; and representative wood moisture-content readings around the interior perimeter of the crawlspace and in the accessible portions of its center. A CL-100 returned with the moisture fields blank is not a compliant report.
- Below the First Main Floor Rule for Fungi:
- Under SC Regulation 27-1085, the legal mandate to inspect and report on wood-decaying fungi (water rot / wood rot) is restricted strictly to structural timbers below the first main floor level (crawlspaces, foundation sills, floor joists, girders, and subfloor sheathing).
- Regulation 27-1085 K(3)(f) defines the line precisely: the first main living-area floor is the first floor above the basement or crawlspace, or the elevated living-area floor in a house raised upon pilings, and the phrase "below the level of the first main living-area floor" also includes the substructure beneath it.
- Decay damage in the upper portions of exterior siding, fascia and trim boards, chimneys, eaves, soffits, and similar areas is expressly beyond the scope of the report.
- But do not over-apply the exclusion: the same paragraph requires that decay damage in the lower portions of exterior doors, door jambs and frames, steps, stairs, porch columns, and similar construction elements MUST be reported. Missing rotted door jambs or porch columns is a classic inspection deficiency.
- The report is also in no way a report on health-related fungi (such as indoor mold) or conditions conducive to them — 27-1085 K(4).
3. Wood Moisture Readings & Decay Fungi Thresholds
Wood-decaying fungi require elevated moisture levels to colonize seasoned lumber, digest cellulose and lignin, and compromise structural load-bearing capacity. Clemson DPR mandates quantitative moisture testing during crawlspace inspections.
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| WOOD MOISTURE CONTENT (MC) DECISION CHART |
| |
| [ < 20% MOISTURE ] ---> NORMAL / SOUND TIMBER |
| Fungi cannot germinate; decay inactive. |
| |
| [ 20% - 27% MOISTURE] -> CONDUCIVE CONDITION / DECAY HAZARD |
| Elevated moisture; conducive to fungal growth. |
| Must be reported; moisture remediation needed. |
| |
| [ >= 28% MOISTURE ] ---> ACTIVE WOOD-DECAY FUNGI INFESTATION |
| Fiber saturation threshold exceeded. |
| Active wood-rot destruction occurring. |
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Mandatory Moisture Benchmarks:
- Below 20% Moisture Content: Lumber is in a dry, stable state. Wood-decay fungi cannot grow or cause structural decay.
- 20% to 27% Moisture Content: Indicates an excessively damp condition conducive to wood-destroying organisms. The inspector must record moisture meter readings on the CL-100 report and document conditions contributing to high moisture (e.g., standing crawlspace water, poor drainage, missing vapor barrier, inadequate foundation ventilation).
- 28% Moisture Content or Higher: Indicates the fiber saturation point where free water exists in wood cell cavities, sustaining active wood-decaying fungi. Active fungal fruiting bodies and structural decay must be reported, and remediation (moisture control + structural repair) is required.
4. Target Organisms Disclosed on the CL-100
The CL-100 requires the inspector to identify, distinguish, and disclose visible evidence of four major groups of wood-destroying organisms:
| Organism Group | Primary Target Species in SC | Key Diagnostic Evidence & Signatures |
|---|---|---|
| Subterranean Termites | Native Subterranean (Reticulitermes spp.), Formosan Subterranean (Coptotermes formosanus) | Earthen mud shelter tubes on foundations/sills, discarded alate swarmer wings, hollowed wood with carton material. |
| Drywood Termites | Cryptotermes, Incisitermes species | Distinctive 6-sided concave fecal pellets (frass) ejected from kick-out holes in dry timber (attics, door frames). |
| Powderpost Beetles | True Powderpost (Lyctinae), Deathwatch/Anobiid (Anobiidae), False Powderpost (Bostrichidae) | Fine, talcum powder-like frass (Lyctids) or gritty coarse frass (Anobiids); tiny round/oval exit holes (1/16" to 1/8"). |
| Old House Borers | Hylotrupes bajulus (Cerambycidae) | Large oval exit holes (1/4" to 3/8") in softwood joists; coarse barrel-shaped frass pellets; audible chewing sounds. |
| Wood-Decaying Fungi | Brown rot (cubical rot), White rot, Poria (Meruliporia incrassata) | Spongy, crumbly wood checking across grain into cubes; white fibrous stringy decay; surface fungal mycelia below first floor. |
Distinguishing Active Infestation vs. Past Damage:
The inspector must make a clear statutory distinction between:
- Active Infestation: Presence of live insects, fresh mud shelter tubes containing termites, fresh powdery frass falling from exit holes, or active fungal growth.
- Previous Infestation / Past Damage: Old, vacant galleries, dry brittle mud tubes with no live insects, weathered exit holes, or stained lumber showing prior water contact without active moisture or live organisms.
- Evidence of Prior Treatment: Drill holes in masonry slabs/foundation walls, treatment plugs, chemical barrier disclosure stickers, or bait station installations around the perimeter.
5. What the CL-100 Is NOT: Legal Disclaimers
To prevent legal disputes and consumer misunderstandings, South Carolina law clearly defines the statutory boundaries of the CL-100 report:
- NOT a Structural Engineering Guarantee: The pest inspector evaluates the presence or absence of WDO evidence; the inspector is not a structural engineer and does not calculate load-bearing capacities or structural stability.
- NOT a Whole-Home Building Inspection: The CL-100 does not evaluate roof shingles, electrical wiring, plumbing, HVAC systems, or building code compliance.
- NOT a Warranty or Service Contract: The CL-100 reports conditions on the exact day of inspection. It does not provide future protection or guarantee that pests will not emerge after the closing date. (Termite warranties and re-treatment bonds are separate contractual agreements).
6. Structural Licensing Categories: Category 7A & 7B
Executing structural pest control and issuing Wood Infestation Reports in South Carolina requires specialized licensing under Clemson DPR:
- Category 7A (Industrial, Institutional, Structural, & Health-Related Pest Control): Authorizes applicators to inspect structures, issue CL-100 Wood Infestation Reports, perform subterranean and drywood termite treatments (liquid soil barriers, borate wood treatments, termite baiting systems), and control household structural pests.
- Category 7B (Structural Fumigation): Authorizes applicators to perform enclosed space and structural fumigations using highly toxic restricted-use gases (such as sulfuryl fluoride / Vikane or phosphine) to eradicate drywood termites, powderpost beetles, or stored product pests within buildings, grain silos, or commodities.
A Category 7A inspector completes an Official South Carolina Wood Infestation Report (Form CL-100) on May 1st. The real estate closing slips to June 15th and the lender refuses the report. What is the correct explanation of the 30-day rule?
During a crawlspace inspection for a CL-100 report, an inspector records a wood moisture content reading of 29% in the subfloor joists beneath a bathroom. How must this finding be categorized on the official report?
Under South Carolina Regulation 27-1085, what are the spatial limits for the mandatory inspection of wood-decaying fungi on the Official Wood Infestation Report (Form CL-100)?
During a CL-100 inspection the licensee finds soft, crumbling decay in the bottom six inches of a front porch column and in the lower portion of an exterior door jamb, plus weathered decay on a second-story fascia board. What must be reported?