We have a lot(!) of ants suddenly crawling out of the baseboard. So they're coming out of the floor from somewhere.
We think: Either: The ants have always been under the floor and are only coming out now because of the heat from the underfloor heating.
Or: The landscaper damaged the wall during excavation, so the ants found an entrance.
or: a crack or hole was made in the exterior wall during construction, but it wasn't until after the garden was re-cultivated that an ant colony appeared in close proximity to the house, so the ants are only now using that access.
What should we do?
Remove the baseboard and see exactly where they come out.
Then go to a hardware store and buy ant powder. Take some powder, dissolve it in water and pour some of it directly into the hole where the ants are coming out. A few drops are enough. I do the same thing outside between the stones. After that you won't see any more ants. After that you can cover the hole with a small amount of Band-Aid and that's it.
And I don't immediately understand why people assume there is a construction defect here. Eventually you will find a lot more insects in or around your house. That's nature's way. It tries to give back what people have deprived it of.
We also find spiders in the house every year, especially when fall approaches. We don't care. We leave them alone, and in return they leave us alone.
This year we also found a few in the candy cabinet after our garden was over. Watched for 2-3 days to see where they came from. They managed to get in through the front door seal and then migrate across the tile base into the living room.
I bought some anti-ant stuff at the hardware store and within a week they were gone.
Remove the baseboard and check. Start fighting (bait cans, sprinkle poison behind the baseboard).