What Older Buildings Offer an Ant
Windsor has a lot of older housing, and older buildings were put together in ways that suit ants. Walls were bedded in lime mortar, softer than modern cement. Ground floors were often timber boards on joists over a ventilated void. Every change since, a new pipe, a blocked fireplace, a replaced window, has left its own small gap.
None of that means the house is in trouble. Black garden ants do not eat timber and they do not attack the structure. What they do is use what is already there: a warm, dry void to nest in, and a crumbly joint or open crack to travel through.
Soft Mortar and Wall Bases
Lime mortar is easy for ants to work. Over time a colony at the base of an old wall can remove fine grains from the joints, and you may notice small heaps of sandy dust on the path or the window sill below. That is a sign of where they are, rather than a sign the wall is failing.
Worth doing: look along the bottom course of brick or stone on the sunny sides of the house on a warm afternoon. Ants coming and going from one joint, or fine spoil collecting against the wall, tell you where the nest entrance is. Repointing can wait until the nest has been dealt with; pointing over an active colony tends only to move the entrance a little further along.
Floor Voids, Hearths and Old Gaps
A suspended timber floor has a space underneath that is sheltered and, near a chimney breast or heating pipes, often warm. Ants that nest there come up where they can: through gaps between boards, along the back of skirting, round the edge of an old hearth or up beside a pipe. The trail seems to begin in the middle of the room because the real route is below it.
- Gaps where floorboards meet the skirting.
- The edge of a hearth slab or a blocked-up fireplace.
- Holes cut for heating pipes and never filled.
- Old airbricks, whose grilles are a way in as well as a vent.
- Joints around door and window frames where the wood has shrunk.
The thing that matters most: in an old house, where you see ants is usually not where they live. Treat the surface and the colony underneath carries on, so the route has to be followed back first.
Houses of the late Victorian and Edwardian period, with bay windows and suspended floors of their own, are covered in more detail on the Caversham page. For what ants can and cannot do to a building, see do ants cause damage to your home.
Treating Without Taking the House Apart
Nobody needs to lift the floor. Gel bait is placed in the cracks the ants are already using, out of reach, and the workers carry it down into the void and share it with the colony and the queen. Outside, a residual insecticide goes in at the nest entrance, along the wall base and at the gaps they use to get inside.
Expect some activity for a few days while foragers pick up the bait. Leave the treated spots alone for as long as you are told, without cleaning or spraying over them. Children and pets are kept off treated areas until dry and as instructed on the day, and it helps to tell us at booking about children, pets, fish tanks or anyone vulnerable at home.
Ant control is a fixed £240, confirmed before anything is booked. What the treatment involves in your building is explained before you decide, including anything about getting at the wall bases or under a floor hatch.
Closing the Gaps Afterwards
Once the colony has gone quiet, sealing the old routes makes the house less inviting to the next one. Fill the gap along the skirting, pack round pipes, keep soil and planting clear of airbricks and the damp-proof course, and have soft or open joints repointed in a mortar that suits the wall. In a listed or historic building, ask a builder familiar with lime before reaching for cement.