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

We are not suggesting period property is a problem. What is true is that certain construction details create routes that a modern build simply does not have, and knowing which ones saves a great deal of searching.

Suspended Timber Floors

The single biggest difference. A suspended ground floor sits over a ventilated void, and that void is deliberately open to the outside through air bricks. It runs under the whole floor area, connects to the wall cavities in many cases, and gives access to the underside of every floorboard in the house.

• Check every air brick for cracked, missing or badly fitted covers
• Look at where pipes and cables drop through the floor — under the sink, at radiators, by the boiler
• Look at gaps at the edges of floorboards, particularly at the perimeter
• Check where a later kitchen or bathroom has been cut into the floor
• Look under the stairs and in any under-floor access hatch

Soft Lime Mortar and Failed Pointing

Lime mortar is softer than modern cement, and where pointing has weathered a mouse can enlarge an opening without much difficulty. BPCA put a mouse at a gap of 5mm; a missing chip of mortar at a perpend joint is frequently more than that.

Service Runs Added Over a Century

A period house has been re-plumbed, rewired and re-heated several times, and every one of those left a hole through something. Old gas pipes capped off in a wall, abandoned electrical runs, a former range flue, an old outside toilet connection — these are the routes nobody knows about because nobody made a record.

The Rest of the List

• Cellars and basements, including coal chutes and light wells
• Open eaves, common on pre-war property and often with no closure at all
• Lath and plaster, where a failed section gives access to the void behind
• Boxed-in pipework, which forms a vertical route between floors
• Original single-skin walls in an outrigger or a rear addition
• Where an extension meets the old building, which is where shrinkage and movement cracks appear
• Roof spaces with no ceiling insulation seal at the wall head

What This Means for Proofing

More points, and some of them structural rather than a matter of filling a gap. Proofing an older property is usually a longer job than a modern one, and some of it belongs to a builder rather than to us — we will tell you plainly which is which rather than charge you by the hour for something we cannot finish.

The high-value items are almost always the air bricks, the under-floor void penetrations and the eaves. Those three account for most of what we find in period property.