Beyond the Home Inspection: Which Other Inspections Come Up When Buying in DC, Maryland, or Virginia?

Why the Standard Home Inspection Is Only One Piece of the Picture

A general home inspection is the step most buyers expect once a contract is signed. It is a thorough review of a home’s major systems and structure, and it is rarely the only evaluation that comes with a purchase. Matt Cheney, a Compass real estate advisor serving Washington, DC, Northern Virginia, and Maryland, explains that buyers commonly schedule additional inspections beyond the typical home inspection. The three most common are wood-destroying insect (WDI) inspections, radon testing, and well and septic evaluations.

This article walks through what each of those three inspections covers, when each tends to happen, and which kinds of properties they apply to. Requirements can vary by county, state, lender, and contract, so this is general information meant to help buyers ask better questions. It is not a substitute for guidance on a specific property, and buyers should confirm current requirements with their agent, their attorney, and the local health or permitting office.

WDI Inspections: Checking for Wood-Destroying Insects

WDI stands for wood-destroying insects. Termites are the example most people think of, and Matt Cheney uses them as the shorthand when he explains the inspection. In the Mid-Atlantic, the category also includes carpenter ants, carpenter bees, and powderpost beetles. A licensed inspector looks for visible evidence of insect activity, past treatment, and wood damage, along with conditions around the home that can invite an infestation.

The inspection is generally non-invasive and focuses on areas the inspector can reasonably reach, such as the exterior, basement, crawl space, and attic. Areas that are blocked or inaccessible are typically noted on the report, which is one reason buyers benefit from clearing access to storage areas and mechanical rooms before the appointment.

When a WDI inspection typically happens

Matt Cheney notes that a WDI inspection is often done about a week or so after the initial home inspection. The actual timing depends on the deadlines in the contract and on the inspector’s availability, so buyers tend to be better positioned when the appointment is lined up early rather than after the general inspection wraps up.

What the WDI report is used for

The inspector documents findings in a written report. In Maryland, licensed inspectors report on a state-designated form, and the national NPMA-33 form is commonly used in other jurisdictions. Some lenders require a WDI report as part of financing, so buyers should ask their lender early whether one is needed for their loan.

If the report notes active infestation, past treatment, or damage, the next step is typically a conversation among the buyer, the seller, and both agents about treatment, repair, or further evaluation by a qualified professional. What is negotiable depends on the contract and on what the report finds.

Radon Testing: Why the Lower Level Gets the Attention

Radon is a naturally occurring radioactive gas that comes from the soil. It has no color or odor, and it can enter a home through cracks and openings in the foundation. The EPA identifies radon as a health concern and has historically used 4.0 picocuries per liter (pCi/L) as the level at which it recommends taking action. Buyers should verify the current EPA guidance directly, as recommended thresholds may be updated over time. Because radon enters from the ground, testing is often placed in the lower level of the home, and Matt Cheney points to the basement as the usual location.

Where radon testing is required

Radon testing is a routine consideration for buyers in Maryland, and the rules depend on the county. In Montgomery County, which includes Potomac and Bethesda, county law requires a radon test on single-family homes and townhomes before a sale can be completed. That requirement has been in place since October 1, 2016, though buyers and sellers should confirm current requirements with their agent and the Montgomery County Department of Permitting Services, as local rules may be updated.

The test must be performed within one year of settlement, it can be done by the seller, the buyer, or a third-party professional using an approved device, and both parties receive a copy of the results. Some exceptions apply, including condominiums, certain municipalities, and certain types of sales.

Elsewhere in Maryland, buyers generally have the right to test under the standard contract, and sellers must disclose known radon issues on the state disclosure or disclaimer form. Requirements in DC and Virginia differ from Maryland’s, so buyers outside Maryland should ask their agent how radon testing is handled for the property they are considering.

What happens if the result is elevated

Radon testing often starts with a short-term test. If the result comes back at or above the EPA action level, a follow-up test is commonly recommended to confirm it. Radon mitigation systems are available to reduce levels in a home. The Montgomery County requirement covers testing rather than mitigation, so the response to an elevated result is typically worked out between the buyer and the seller during the inspection period.

Well and Septic Inspections: Homes Without Public Water or Sewer

Matt Cheney explains that when a home is not on public water or public sewer, the well and the septic system need to be tested. He points to Potomac and Great Falls as familiar examples. It is worth noting that those are two different jurisdictions. Potomac is in Montgomery County, Maryland, and Great Falls is in Fairfax County, Virginia, so the rules and the local offices involved are not the same. Whether a specific property is connected to public utilities or relies on private systems can vary from one street to the next, so buyers should confirm how a given home is served early in the process.

The well

A private well is the home’s own water source. A well evaluation commonly includes a water quality test through a certified laboratory and a review of the well equipment and flow. In Maryland, water quality testing requirements tied to the sale of a property with a private well have been in effect since October 1, 2024. Maryland buyers and sellers should confirm current requirements with their agent and attorney before proceeding, as implementation details and any subsequent amendments should be verified directly with the Maryland Department of the Environment or a local real estate attorney. Lab results can take time to come back, which is another reason to schedule early.

The septic system

A septic system treats household wastewater on the property instead of sending it to a public sewer line. A septic inspection typically evaluates the tank, the components that distribute wastewater, and the drain field where treated water disperses. Depending on the property and the inspector, a tank pump-out may be part of the process so the condition of the tank can be seen. Because these systems sit underground, the inspection is what gives buyers visibility into how the system is performing.

Local agencies oversee these systems. In Montgomery County, the Department of Permitting Services handles well and septic testing and permitting, and in Fairfax County, the Health Department oversees the installation, maintenance, and monitoring of private wells and septic systems.

How These Inspections Fit Into the Contract Timeline

Each of these inspections has its own professional, its own schedule, and its own report. A few planning points can help the process run more smoothly:

• Ask the agent which inspections apply to the property type and location before writing an offer, since that can shape the length of the inspection period.
• Ask the lender whether a WDI report or any well and septic documentation is needed for the loan.
• Line up specialists early, since appointment availability and lab turnaround may affect the schedule.
• Read each report in full and bring questions to the agent, rather than relying on a summary page alone.
• Talk through the results with the agent before deciding on next steps such as repair requests, credits, or further evaluation.

Depending on the property, other specialized evaluations may also come up, such as chimney or sewer line inspections. Matt Cheney can help buyers sort out which additional inspections fit a specific home and how to sequence them alongside the general home inspection.

Working With Matt Cheney on Inspections and Due Diligence

Matt Cheney has guided buyers and sellers across DC, Maryland, and Virginia for more than 23 years, and inspection strategy is a regular part of that work. Because requirements differ by jurisdiction, property type, and lender, having an advisor who works across all three markets can help buyers avoid surprises during the inspection period.

Buyers with questions about which inspections apply to a specific property can contact Matt Cheney at Compass Real Estate, 5471 Wisconsin Avenue, Suite 300, Chevy Chase, MD, by phone at (202) 465-0707, or through mattsold.com. For more on how Matt guides buyers through due diligence across DC, Maryland, and Virginia, visit mattsold.com/buyers.

Frequently Asked Questions About Other Types of Home Inspections

What are the most common inspections buyers schedule beyond a standard home inspection?

Matt Cheney identifies three: WDI inspections, radon testing, and well and septic evaluations. WDI and radon testing come up in many purchases, while well and septic evaluations apply when a home is not on public water or public sewer. Depending on the property, other specialized evaluations may also be considered.

What does WDI stand for?

WDI stands for wood-destroying insects. The inspection looks for visible evidence of insects such as termites, carpenter ants, carpenter bees, and powderpost beetles, along with past treatment and wood damage.

When is a WDI inspection typically scheduled?

Matt Cheney notes that it is often done about a week or so after the initial home inspection. Contract deadlines and inspector availability can change that timing, so buyers should coordinate the appointment with their agent early.

Is radon testing required when buying a home in Maryland?

In Montgomery County, county law requires a radon test before the sale of a single-family home or townhome can be completed, with some exceptions. Elsewhere in Maryland, buyers generally have a contract right to test, and sellers must disclose known radon issues. DC and Virginia have different requirements, so buyers should confirm how radon is handled for a specific property with their agent.

Where in a home is radon usually tested?

Testing is often done in the lower level of the home, commonly the basement, because radon enters from the soil beneath the foundation.

Which homes need well and septic inspections?

Homes that are not on public water or public sewer. Matt Cheney points to areas such as Potomac, Maryland, and Great Falls, Virginia, as familiar examples, though the specific rules and local offices differ between the two.

Who pays for these inspections?

Responsibility depends on the contract, local requirements, and negotiation between the parties. Matt Cheney can walk buyers through how it is typically handled in a specific transaction.

What happens if an inspection finds a problem?

The options depend on the contract and on what the report shows. Buyers commonly discuss repairs, credits, or further evaluation with their agent, and the seller may respond in different ways. Reviewing the report in detail with an experienced agent can help buyers weigh the choices.