Termites and other wood-destroying insects eat the parts of the house you are counting on for structure, and they do it where paint and carpet hide the damage. Subterranean termites are the main issue in most of the country. Drywood termites matter in warmer coastal and southern markets. Carpenter ants and powderpost beetles get lumped into the same inspection and are not the same bug. The report you want is a wood-destroying insect inspection, often called a WDI or NPMA-33, not a generalist's sentence that says "no pests noted."

A clear letter is a snapshot. It is not a warranty that joists are solid, and it expires as a practical matter in weeks to months, which is why lenders ask for a recent one.

What it is

Subterranean colonies live in the soil and build mud shelter tubes to reach wood. The damage is often at sill plates, rim joists, and any wood that touches soil or stays damp. Drywood termites live inside the wood and leave hard fecal pellets. Both can be active with the lawn looking perfect. Moisture is the partner: a wet basement or a leaking crawlspace is an invitation.

How to spot it in the listing

Geography and age. The southeast, Gulf Coast, California, Hawaii, and parts of the desert southwest have higher pressure. Any market with a crawlspace and wood-to-soil contact belongs on the list. Photos sometimes show mud tubes on a foundation pier if the photographer shot the crawlspace, which is rare. "Termite bond transferable" is useful. Read what it covers: retreatment only, or repair of damage too. A bond that retreated last year and excludes existing damage means you may be buying the damage.

Prior listings and permits sometimes mention "termite damage repaired" at a sill or a front porch. Compare older exterior photos. A replaced skirt board or a new section of porch floor on an otherwise tired house is a place to ask why. The Street View comparison helps on the outside. It will not see the sill.

How to spot it at the showing

Mud tubes on foundation walls, piers, and the inside of crawlspace walls. Wings discarded near windows in spring. Soft wood at the base of door frames when you press it. Paint that blisters at the bottom of siding for no paint reason. In a crawlspace, wood debris and form boards left on the soil are food. You should not army-crawl a dirty crawlspace in showing clothes and call that an inspection. Hire the WDI inspector with a light and a probe, and make sure they will enter the crawlspace. A report that says "inaccessible" is not a clear report.

The real risk

Structural damage that is already done is a carpenter's bill, not a pesticide bill. Treatment stops the colony. It does not replace a sill plate. In high-pressure regions, an untreated house is a matter of when. In low-pressure regions, a tubed foundation is still a when.

Insurance and lending

Standard policies exclude insect damage. There is no claim coming. Some lenders, and many in the southeast, require a clear WDI report dated close to closing. VA loans are strict about it. FHA appraisers can require repair of structural damage and treatment of active infestation. A "cleared with conditions" report that says damage at the sill was not probed is how closings stall in the last week. Order the report inside the inspection contingency, not the week of closing.

Typical cost ranges

Typical ranges, not quotes.

WDI inspection: often $75 to $200, more if the crawlspace is hostile or they charge to return.
Subterranean treatment (liquid barrier or bait system) on an ordinary house: commonly $800 to $2,500, plus an annual renewal if you want the bond.
Drywood treatment (fumigation of the whole structure, in markets where that is the method): often $1,500 to $4,000 or more, and you have to leave.
Repair of damaged sills, joists, or a porch: the open-ended part. A small accessible sill might be $1,500 to $5,000. A main beam and several joists, or a slab with hidden damage, moves into five figures fast.

Get treatment and repair as separate numbers. A pest company that also "does the carpentry" needs a license for both, and you need to see the wood.

Pass, negotiate, or investigate

Investigate with a real WDI any time the region, the crawlspace, or the age says so. Do it even when the seller has a letter from the spring. Negotiate treatment plus repair when tubes or damage are confirmed and you have both bids. Pass when the inspector cannot access the structure, the seller will not open it, and you are supposed to waive the report. You cannot price what nobody looked at. Put the WDI next to the general inspection on the checklist, not as an afterthought when the lender asks.

Termites: Mud Tubes, Soft Trim, and the Report That Is Not a Warranty