Do not fill or cover an opening until someone has identified what it does. An air brick, eaves gap, duct grille or service penetration may be relevant to pest access, but proofing must preserve required airflow, drainage, fire performance, inspection and maintenance. The relevant building professional should specify the compliant repair.
In England, Approved Document F provides statutory guidance on ventilation requirements, while Approved Document B covers fire safety and the treatment of openings through fire-resisting elements. The edition and requirements that apply depend on the building and work, which is why the proofing detail needs competent review rather than a universal filler or mesh instruction.
Record the opening in context
Photograph the whole wall, roof edge or service area before taking a close-up. Give the opening a location, dimensions where safely measurable, nearby room use and any product marking. Note damp, condensation, blocked grilles or mechanical plant because they may reveal the opening’s function.
Keep pest evidence in a separate field. Droppings near an air brick can justify investigation; they do not authorise sealant across it. Likewise, an opening that looks large enough for an animal is not automatically an active route. Record sightings, damage and monitoring results without making the building specification depend on a guess.
Existing drawings, operation manuals or fire-stopping records can help identify requirements. Where those are missing, refer the detail to the person responsible for ventilation, fire safety, roofing or the relevant service.
Ask for a performance-based proposal
The contractor should explain what component will be repaired or added, what material and fixing are proposed, and how the original function remains. Ask how the detail handles airflow, water, condensate, cleaning, corrosion and access. If mesh or a grille is proposed, request the product specification and confirmation from the responsible designer or trade that it suits the building system.
For example, a damaged air brick beside mouse evidence may need replacement or a designed protective grille. Blocking its face might reduce the visible gap while creating a ventilation problem. The pest record explains why action is needed; it does not set the airflow requirement.
Coordinate the sequence when treatment or monitoring is underway. Closing a route while activity remains uncertain can change movement or make devices harder to interpret. Agree who authorises closure, who completes it and how both the building detail and pest objective are checked.
Keep a verifiable handover
The completion record should include before-and-after photographs, exact product or repair, installer, date and any area not seen. Add the maintenance and cleaning route. If later condensation, damage or pest evidence appears, the record allows the right specialist to compare the change.
Do not ask a pest technician to certify ventilation, fire stopping or structural compliance unless they are separately competent and appointed for that work. Equally, ensure the building contractor understands the identified pest route and timing.
Call The City Pest Company on 0203 393 2338 for the pest-inspection part of the problem. See the mouse service page for context; building-system design remains with the relevant professional.
FAQs
Can ordinary mesh be fitted over any vent?
Do not assume so. Material, aperture, fixing, airflow, fire and maintenance requirements depend on the component and building.
Who should approve the proofing detail?
The person competent and responsible for the affected building system, informed by the pest-route evidence.
Is expanding foam a universal solution?
No. The correct material depends on the opening’s function and required performance.
Sources and further reading
External references may contain pest or skin photographs.
