When you’re buying a home, the standard inspection covers a lot of ground. Roof, foundation, electrical, plumbing, HVAC, all the big stuff. But there are a handful of specialized inspections that don’t automatically come with the basic package, and skipping them can end up costing you a lot more down the road. One example many buyers haven’t even heard of is what is a WDO inspection, which stands for wood destroying organisms, and it’s more important than the name might suggest.

What Is a WDO Inspection and Why It Matters

A wood destroying organism inspection checks for termites, carpenter ants, wood boring beetles, and any fungus or decay that damages the structural wood of a home. This is especially important in warmer, humid climates where these pests thrive, but it’s a smart move almost anywhere. Termite damage in particular can go unnoticed for years, quietly eating away at support beams and framing until the damage becomes a real structural concern.

Many mortgage lenders actually require a WDO inspection before approving a loan, especially in certain states or regions known for termite activity. Even when it’s not required, it’s a relatively small cost compared to the thousands of dollars it can take to repair termite damage once it’s spread through a home’s structure.

Radon Testing

Radon is a naturally occurring gas that you can’t see, smell, or taste, which is exactly why testing for it matters so much. It seeps up from the ground and can collect in basements and lower levels of a home, and long term exposure has been linked to serious health risks. Radon levels can vary a lot even between homes right next to each other, depending on the soil and how the house was built.

Testing usually takes a few days and involves placing a small device in the lowest livable area of the home. If levels come back high, a mitigation system can be installed to vent the gas safely outside. This is a fairly affordable fix compared to the peace of mind it provides, especially for a home you plan to live in for years.

Sewer Inspection

A sewer inspection is another add on that often gets skipped simply because most buyers don’t think to ask for it. This involves sending a small camera through the home’s main sewer line to check for cracks, blockages, tree root intrusion, or other damage that isn’t visible from the surface.

Older homes are especially prone to sewer line issues, particularly if they still have original clay or cast iron pipes. Replacing a damaged sewer line can be one of the more expensive repairs a homeowner faces, so a camera inspection before closing gives buyers a much clearer picture of what they’re getting into.

Mold Inspection

A mold inspection is worth considering anytime there’s visible water damage, a musty smell, or a history of leaks or flooding in the home. Mold can grow behind walls, under flooring, and inside HVAC systems, often in places a general inspector wouldn’t check without specialized tools.

This type of inspection typically involves both a visual assessment and air or surface sampling to check for mold spores. If mold is found, the report will usually include recommendations for remediation and an estimate of how serious the problem is.

When You Actually Need These Add Ons

Not every home needs every one of these inspections, but certain situations make them worth the extra cost.

1. Older homes, especially those over thirty or forty years old, benefit from a sewer inspection given how much pipe materials degrade over time.
2. Homes in regions known for high radon levels should always get tested, regardless of the home’s age.
3. Any home with a documented history of water damage or a musty smell should get a mold inspection before closing.
4. Homes in warm or humid climates, or areas with a known termite presence, should include a WDO inspection as a standard part of due diligence.

Weighing the Cost

Each of these add on inspections typically costs somewhere between a couple hundred dollars, which feels like a lot when you’re already stretching your budget for a down payment and closing costs. But compared to the potential cost of a termite infestation, a radon mitigation system installed after the fact, a collapsed sewer line, or a full mold remediation project, the upfront cost is minor.

The real value of these inspections isn’t just catching problems early. It’s giving you the information you need to negotiate repairs, walk away from a bad deal, or simply go into homeownership with your eyes open. A few hundred dollars spent now can save you from a financial headache that shows up right after you move in.