South Carolina Home Inspection: CL-100, Radon, and Septic — What Every Buyer Must Order

South Carolina is a caveat emptor state. The seller discloses only what they actually know. If they genuinely do not know about a rotting sill plate under the crawlspace or an elevated radon level in the basement, they bear no liability for failing to tell you. The burden of discovery falls entirely on the buyer — and the due diligence period is the only protected window to exercise it.

A standard home inspection covers the visible systems: roof, structure, HVAC, plumbing, electrical. In South Carolina, a standard inspection is not enough. There are three additional evaluations that are either legally required for certain financing or practically essential given the state's climate and geology: the CL-100 Wood Infestation Report, radon testing, and septic inspection. Understanding what each one covers — and what it costs — is the foundation of real due diligence.

The CL-100 Wood Infestation Report: Near-Mandatory for Financed Purchases

South Carolina's humidity, pine forest ecosystem, and subtropical climate make it one of the most active termite environments in the country. Subterranean termites, powderpost beetles, and wood-decaying fungi can destroy structural members silently, leaving no visible surface evidence until the damage is severe.

The CL-100 is the Official South Carolina Wood Infestation Report — a specialized structural evaluation performed exclusively by a state-licensed pest control operator. It documents the presence or absence of:

• Active termite infestations
• Evidence of prior (possibly untreated) termite activity
• Wood-destroying beetles
• Wood-decaying fungi
• Moisture damage to structural wood members

Cost: $75 to $160 for a standard residential inspection.

The 30-day expiration rule: A CL-100 is legally valid for only 30 days from the inspection date. This is not a guideline — it is a statutory requirement. If your closing is delayed beyond 30 days after the CL-100 was performed, the report is invalid and a new inspection must be ordered at additional cost. This is a common source of closing delays when buyers are not aware of the expiration in advance.

Which loan types require it:

• VA loans: The Department of Veterans Affairs categorizes South Carolina as a high-risk termite zone and universally mandates a "clear" CL-100 for all previously occupied homes before issuing a Notice of Value. A VA loan cannot close without CL-100 clearance. Period.
• FHA loans: Most FHA lenders in South Carolina require a clear CL-100 to protect the underlying collateral.
• Conventional loans: Not always legally mandated, but most conventional lenders also require it to protect their investment.

What happens if the CL-100 finds damage: If active termites or structural damage is found, the seller is typically required to arrange for chemical treatment and structural repair before the lender will authorize final funding. These repairs can range from a few hundred dollars for spot treatment to tens of thousands if significant structural members need replacement. Negotiate the repairs during your due diligence window — do not accept a credit in lieu of actual remediation if the damage is structural.

Order the CL-100 immediately after contract execution. Do not wait. Given the 30-day expiration and the possibility of closing delays, ordering it on day one of your due diligence period gives you maximum flexibility.

Radon Testing South Carolina: Where the Risk Is Highest

Radon is a naturally occurring, odorless, radioactive gas produced by uranium decay in rock and soil. It is the second leading cause of lung cancer in the United States after smoking. In South Carolina, radon risk varies dramatically by geography and is closely correlated with the state's underlying geology.

The Upstate and Piedmont: High Risk

Counties in the Upstate and Piedmont regions — Greenville, Spartanburg, Pickens, Oconee, Cherokee, Union, and Cherokee — sit on granitic and metamorphic bedrock formations with elevated uranium content. The EPA classifies multiple Upstate South Carolina counties as Zone 1 (Highest Potential), indicating average indoor radon screening levels that consistently breach the 4.0 picocuries per liter (pCi/L) action threshold.

If you are buying anywhere in Upstate or Piedmont South Carolina, radon testing is not optional — it is essential. A continuous digital radon monitor placed during your due diligence period provides accurate results in 48 to 96 hours. Testing typically costs $100 to $200 when ordered through your home inspector.

If levels above 4.0 pCi/L are detected, the standard mitigation approach is a sub-slab depressurization system — a pipe and fan system that draws radon from below the foundation and vents it above the roofline before it can enter the home. Installation cost: approximately $800 to $1,500 for a standard single-pipe system. Negotiate mitigation as a seller repair during your due diligence period.

The Lowcountry and Coast: Low Radon Risk

Charleston, Beaufort, Horry, and Georgetown counties sit on coastal sedimentary soils with low uranium content. Radon risk in these counties is minimal, and mandatory testing is rarely requested by lenders. Buyers in these markets face different environmental challenges — specifically flood risk and saltwater-related corrosion — rather than radon.

Septic System Inspections: The Most Overlooked Due Diligence Item

Outside of Charleston, Columbia, and Greenville's municipal water and sewer grids, a large portion of South Carolina properties — particularly in rural and exurban areas — rely on individual onsite wastewater systems (septic tanks). A septic system is among the most expensive home components to replace. Understanding its condition before closing is critical.

A standard visual home inspection is not a septic inspection. Your general home inspector will note that a septic system is present and may observe the system from the surface, but they are not equipped to evaluate whether the system is functioning properly. A dedicated septic inspection requires:

1. Locating and exposing the tank access port
2. Pumping the tank to inspect the concrete baffles (inlet and outlet) for integrity
3. Camera or dye inspection of the lateral drain field lines to assess absorption capacity
4. Documentation of the system's permit history and compliance status

Septic replacement costs in South Carolina:

Replacement cost depends heavily on soil type and water table:

Discovering a failing septic system after closing — particularly one that requires a $15,000 engineered alternative system — is a devastating financial event. Septic inspections during due diligence typically cost $300 to $600 depending on accessibility and the scope of the evaluation. That cost is trivial relative to what it protects against.

SCDES permitting: New septic systems in South Carolina require approval and permitting through the South Carolina Department of Environmental Services (SCDES). If you are buying a property where a new system must be installed, confirm the soil classifier evaluation and permit approval are in hand before closing — an unapproved system cannot be legally operated.

Putting It Together: A South Carolina Due Diligence Inspection Budget

For a typical resale home purchase, plan your due diligence inspection costs around:

• Standard home inspection: $350–$550
• CL-100 wood infestation report: $75–$160
• Radon test (Upstate/Piedmont): $100–$200
• Septic inspection (rural/suburban properties): $300–$600
• Elevation Certificate (flood zone properties): $300–$600

Total due diligence inspection costs typically run $500 to $1,100 for inland properties and $900 to $1,500 for coastal or rural properties with flood zone or septic complexity.

These are recoverable at closing — SC Housing DPA programs limit cash-back to documented out-of-pocket expenses, which include earnest money and inspection fees you have already paid.

For a complete step-by-step guide to the South Carolina home buying process — including how the due diligence period works under the SC Form 310 contract, what happens at the attorney closing, and every cost you will encounter from offer to key handoff — visit the South Carolina First-Time Home Buyer Guide.

See more South Carolina guides →