Pests in and around buildings — prevention and control
How the hygiene chain is maintained from farm to table
Being able to identify different pests in and around buildings, combat them with both non-chemical and chemical methods within applicable regulations and prevent new attacks is one of the goals you must fulfill as a property service technician. Pests are not just a nuisance — they can spread disease, damage building parts and affect residents' sense of security, so it's a task that must be taken seriously.
§The common pests in Danish properties
- 01Rats and mice — seek food, warmth and shelter, often enter via drains, sewers or gaps in the facade
- 02Cockroaches – thrive in warm, humid environments like basements, technical rooms and kitchens
- 03Wall lice (bed bugs) — spread by luggage and furniture, typically found in beds and upholstered furniture
- 04Wasps and bees — build nests in roof structures, sheds and cavities in summer
- 05Pigeons and other birds — leave droppings that can clog gutters and spread disease.
- 06Moths and mold-related pests — often occur where there is moisture or unhygienic conditions
§Prevention is the most important intervention
The best control is the one that never becomes necessary. Sealing holes and cracks in façade and plinth, correct storage of waste in closed containers, clearing basement rooms and quick repair of leaks remove both food and access paths for pests. As a property maintenance technician, you are the one who first detects signs of infestation — droppings, gnaw marks, larvae or smell — because you go everywhere in the building as part of your daily work.
§Rats are a special case: legally required reporting
Rats are regulated separately in the ordinance on the prevention and control of rats. If you discover rats in or near a property — whether you are owner, tenant or administrator — there is a duty to report it to the municipality, and the deadline is short. The municipality is responsible for effective rat control, either with municipal rat catchers or a pest control company, and the control itself requires authorization: an R1 authorization for commercial prevention and control of rats, or an R2 authorization that applies to control on own business premises.
§Non-chemical and chemical control
Control is broadly divided into two tracks. Non-chemical methods include traps, sealing, behavior change and physical barriers, and are often the first choice because they do not burden the environment and do not require the same level of authorization. Chemical agents — poison and other pesticides — work faster on larger infestations, but must be handled safely, stored inaccessibly to children and animals, and used according to the product's instructions and safety data sheet.
| Pests | Typical method | Requirements for authorisation |
|---|---|---|
| Mus | Traps, sealing | Can often be handled yourself |
| Rats | Traps, poison, sealing | Notification obligation to municipality; professional control requires R1/R2 |
| Cockroaches | Gel bases, hygiene measures | Often specialist company for larger attacks |
| Wasp nest | Removal of nest possibly poisoned | May require a specialist depending on location |
§Documentation and follow-up
Just as with other pest control, an effort to control pests must be documented: what has been observed, when, which method was used, and whether follow-up was done. This makes it possible to see if an attack returns, and it provides a basis if the municipality or a pest control company needs to get involved.
“The best pest control work is the work nobody notices — because it never became an attack.”
— Professional view on prevention in real estate service.