Where Should You Look for Mouse Entry Points Around a March Property?

In a house you look for one boundary: the outside. In a shared building there are two — the outside of the block, and the line between you and everybody else. The second is the one you can actually do something about.

The Internal Boundary

• Service risers. The vertical shaft carrying soil, water, gas, electrical and data between floors. Frequently unsealed at every floor level, and the single most important item on this list
• Party wall penetrations. Anything passing through a shared wall — pipework, cabling, an old flue, a joist end pocket
• Floor and ceiling voids, which often run continuously across the whole building whatever the deeds say
• Boxed-in pipework, which forms a vertical route from the flat below to yours and onwards
• Around the front door frame and into the wall from a communal corridor
• Under a communal corridor floor, or above a suspended ceiling in one
• Meter cupboards and service cupboards, which are usually communal and usually open to the structure
• Lift shafts, refuse chutes and their surrounds in a larger block

The External Boundary, Which May Not Be Yours

Worth looking at, and worth photographing, even where you cannot act on it:

• Bin stores and refuse areas, which is usually where the food is
• Communal entrance doors that do not close properly
• Service entries into the block at ground level
• The roof void, in a terrace or a low block, which may be continuous
• Basements, car parks and plant rooms
• Landscaping and planting against the building

Who Deals With What

What to Do With the List

Seal what is yours — wire wool packed tight and sealed over, or mesh, never foam alone. Photograph and report the rest, in writing, to whoever is responsible. A written survey stating what was found and where the evidence points is frequently the thing that gets a managing agent to act, and it is a fixed cost.

And be realistic about the scope. In a block, a treated flat beside untreated ones gets repopulated. That is not a treatment failure — it is why the building needs treating rather than the flat.