A row of patched holes in the basement floor: was this Marshalltown house treated for termites?

Fall and winter are when the people who just bought an older Marshalltown house start pulling up basement carpet and framing out a rec room. That is usually when someone notices the dots. A line of small gray patches in the concrete, each about the size of a coin, following the floor along the foundation wall. The cement is a shade lighter than the slab around it, and nobody living in the house can say who put it there.

Houses off Center Street and around the square often keep their termite history in the concrete and the framing long after the paperwork has gone missing. Most of it can be found from the basement floor and a walk around the yard.

What are the rows of small patched holes in my basement floor?

Almost always, they are drill holes from an earlier liquid termite treatment. To get the treatment into the soil under a slab, the crew drills through the concrete along the inside of the foundation wall, at cracks, and around the floor drain and the plumbing, then patches each hole. Patches like these say a house was treated once. Whether it is protected now is a question for a termite inspection in Marshalltown.

The same row of patches shows up on concrete outside the basement too. A garage slab drilled along the wall it shares with the house. A front stoop with a few dots across the top step. A patio or a sidewalk poured tight against the foundation, drilled near the edge. Each one is a spot where the treated zone had to pass under concrete, so finding patches in several of them usually points to the same job.

One look-alike to set aside. A single larger hole cored through the slab, with a plastic pipe rising out of it and running up the wall, is a radon system, and it has nothing to do with termites.

What are the round caps in the yard along the foundation?

Round plastic caps set flush with the soil, spaced out around the house, are in-ground termite bait stations. At some point a company set up a monitoring program on this house. Stations only protect while someone services them, so a cap that has not been opened in years marks old work rather than an active defense.

They are easy to miss. Grass grows over the edge, mulch gets raked across them, and a new owner mows around them all summer assuming they belong to a sprinkler or the gas company. The lids often lock and take a special tool to open.

Before anything else, look at the lid. Many carry the treating company’s name or phone number, molded into the plastic or on a sticker, and that is usually the quickest way to trace when the program started and when it stopped. Leave the stations in the ground. Pulling them or rearranging them scrambles the best map of where the work was done, and if the program can be restarted, the company will want them where they were.

What does new wood next to old over the foundation tell you?

New lumber bolted or nailed beside an old joist, a replaced run of sill plate or rim board, a fresh post holding up an old beam. On a basement this age, repairs like these usually mean damage was found. Repairs prove the damage was real. They say nothing about whether the colony that caused it was ever treated.

Look at the color first. Bright, pale framing beside dark, century-old joists stands out even from the stairs. Sometimes the old piece is still there, left in place with the new one fastened against it, and the damage is visible on the old wood’s face. Termite galleries run with the grain, and the old ones often stay packed with dried soil, which is the termite signature.

A repair with no patched holes anywhere in the slab and no caps in the yard is the combination to take most seriously. Someone fixed the wood. There is no sign anyone dealt with the termites, and whether termites are still working in that wall is a separate question from the repair.

Does termite work done years ago still protect the house?

Not reliably. Soil treatments break down over time, and any later work that moves the soil against the foundation breaks the treated zone in that spot. The eastern subterranean termite colonies living in the soil here outlast any single treatment. Bait stations stop protecting the day someone stops servicing them.

On an older house, the later digging usually matters more than the age of the treatment. Over a few decades, plenty of things dig into the soil the original crew treated:

• a new patio or a rebuilt front stoop
• a flowerbed regraded or raised against the house
• drain tile or a new sump
• a porch rebuilt or an addition put on
• a sewer line dug up and replaced

Each one swaps treated soil for fresh fill in that spot. An addition is the plainest case, since its whole footprint sits on dirt nobody treated with the rest of the house.

None of that says the house needs work. The old patches can’t settle it either way. If an inspection does call for re-treating, the cost page lists what re-treating an older house runs in Marshalltown.

Is there paperwork, and does a termite warranty transfer with the house?

Sometimes. The treating company’s records are the useful part: the date, which method was used, and the diagram of the house showing where they drilled or placed stations. Many termite treatments came with a renewable warranty or service agreement, and some companies will move it to a new owner, usually after their own inspection.

Ask the seller first, and look through any folder of house papers left behind in a drawer. Then call the company named on the station lids or on whatever paperwork turns up. What transfers, for how long and at what price is set by that company, and only that company can tell you. An agreement that lapsed years ago may still be useful for its records even if the coverage is gone, since the diagram shows where the old work went.

What does the termite part of a home-sale inspection report actually tell you?

It reports what was visible on the day of the inspection, notes any signs of previous treatment, and lists the places that could not be seen. “No visible evidence” means nothing showed in the areas that could be looked at that day. It is a narrower statement than “no termites.”

That list of places not seen is the section most buyers skim and the one that matters most in an older house. Finished basement walls, carpet over the slab, boxes and shelving stacked against the foundation, a crawl space under an addition with no way in. On a finished basement, that can cover most of the foundation.

Patched holes, caps in the yard and new framing beside old fill those gaps. They tell an inspector the house has a termite history before a single wall comes open. Point them out, along with any paperwork or company name you found.