Where the ants emerge tells you where the nest is. In a period house with a suspended timber floor, that answer is often below you rather than outside.
Where they emerge tells you where the nest is. At a skirting or a door threshold usually means a nest outside, foraging in. In the middle of a floor, or at a hearth, usually means a nest in or under the subfloor void.
The second one is a treatment job. The first often is not.
| Where they emerge | What it usually means |
|---|---|
| At the skirting on an external wall | Nest outside, foraging in through the wall base |
| Under a door threshold | Nest outside, often under the step or path |
| Middle of a ground floor | Nest in or under the subfloor void |
| At a hearth or chimney breast | Nest in the fabric, often warm and long established |
| Around a pipe entry | Following a service run in from outside |
| Upstairs | Travelling a wall void, or possibly pharaoh ants |
| Around a window frame | Nest in the wall or in the frame's surround |
Every one of those is normal for the age of the building. None of them is a fault, and most of them must not be sealed.
Published prices, and honest advice about when treatment is not needed at all.
View Ant Control Pinner →We say this on every period-property visit because we keep finding airbricks that somebody has cemented up to keep something out.
If the ants are very small and yellowish-brown rather than black, and appearing upstairs or near warm pipework, they may be pharaoh ants. They nest inside buildings with multiple queens, and spraying causes the colony to split and spread. Tell us — the approach changes completely.
Where there is access, yes. Where there is not, bait placed at the emergence points is carried down.
It moves them. They will find the next gap. Bait ends the colony.
Black garden ants do not damage timber. They are a nuisance, not a structural problem.
Wasps entering under a roof tile or at the eaves? £90 fixed in Pinner, guaranteed for 30 days.
Usually a nest outside foraging in through the wall base. If they emerge in the middle of a floor instead, the nest is likely in or under the subfloor void.
Suspended timber floors over a ventilated void, boards that have shrunk, solid walls with no cavity, weathered lime mortar, and original airbricks that are open by design.
No. Airbricks ventilate the subfloor void, and blocking them causes damp, rot and eventually joist failure — a far bigger problem than ants.
Internal gaps at the skirting, around internal pipe runs, and at door thresholds. External repointing should use lime mortar on a solid wall, and may need consent on a listed or conservation-area property.
Black garden ants do not damage timber. They are a nuisance rather than a structural problem.
They find the next gap. Bait carried back to the colony is what ends it.
They may be pharaoh ants, which nest inside buildings with multiple queens. Spraying makes them split and spread — tell us before anything is done.
Yes. A garden nest is not a pest. Only the trail indoors is the problem.
Photograph where they come out. Perimeter and mid-floor mean different things — and do not seal the airbricks.
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