Proofing is more than filling a hole.
The correct material and method depend on the location, building fabric, ventilation requirements and evidence of rodent movement. Poorly placed filler can fail quickly or simply move the problem elsewhere.
Common proofing areas
✓ Gaps around service pipes
✓ Air-brick protection
✓ Voids around external walls
✓ Door and threshold gaps
✓ Drain-related entry risks
✓ Roofline or outbuilding access
Inspection first
Where possible, proofing should follow evidence: where pests are travelling, how they are entering, and whether another route will remain open after the work is completed.