Bats in the House: What Should Homeowners Do Now?

What should you do now?

Many homeowners are alarmed when they discover that a colony of bats has moved into their property. The animals are strictly protected, may carry diseases and can cause damage over time. Even so, panic or rushed DIY attempts are the wrong response. By following a few basic rules, you can remove bats from your home humanely, legally and for good.

Why bats choose your home in the first place

Bats are not monsters; from their perspective, they are simply practical tenants. They look for shelters that resemble their natural roosts: warm, dark, protected from predators and as undisturbed as possible.

Lofts, cavities in walls, spaces behind cladding and disused chimneys offer ideal conditions. Bats gain access through exceptionally small gaps. Many species can fit through openings barely wider than half a centimetre. Even modern, well-built homes are therefore not automatically protected.

A building becomes especially attractive when suitable conditions are also available nearby:

• Water sources such as ponds, rivers or ditches
• Gardens, traditional orchards, woodland or hedgerows
• Large insect populations, for example around agricultural land

Bats consume huge quantities of mosquitoes and other insects every night. Anyone living in this type of setting is statistically more likely to have them nearby. Cities are no exception either: street lights attract insects, and therefore the animals that hunt them.

Typical signs that bats are in the house

Acting early can prevent large colonies and costly repair work. Possible warning signs include:

• Quiet squeaking or scratching shortly after sunset or before sunrise
• Dark greasy marks around gaps, cracks and projections in masonry, caused by body oils
• Piles of dark, crumbly droppings (guano) on floors, window ledges or roof timbers
• Direct sightings: bats repeatedly emerge from the same opening in the evening

“Anyone who repeatedly sees bats entering and leaving from the same spot is very likely to have a roost in the house and should act promptly.”

Guano is more than merely unpleasant. It can contain the fungus Histoplasma capsulatum, which may cause respiratory infections if inhaled. Cleaning it up without a protective mask and disposable clothing is therefore a bad idea.

Legal restrictions: why bats cannot simply be made to “go away”

Bats receive strict protection in Germany and many other countries. Numerous species are threatened, partly because of habitat loss and diseases such as so-called white-nose syndrome.

Anyone who kills or captures bats, or destroys their roosts, risks substantial fines. In some cases, rules such as the Federal Nature Conservation Act (Bundesnaturschutzgesetz) or dedicated species-protection programmes also apply. For this reason, always ask the lower nature conservation authority, the environmental office or a regional bat adviser before undertaking major work.

The right time: when exclusion is permitted and sensible

The period in which female bats raise their young is particularly sensitive. At this stage, the pups remain in the roost and cannot yet fly. If the mothers are prevented from returning, the young die painfully, while the loft can become a health and odour problem.

During winter, individual species may hibernate inside a house, often deep in narrow crevices. Carrying out uncontrolled repairs can wake them from hibernation and put their lives at risk, as their fat reserves may no longer last until spring.

How humane bat exclusion works in practice

The preferred approach is to use one-way exclusion devices. These allow bats to leave their roost at dusk but stop them from getting back in through the same opening.

One-way bat exits: patience rather than force

These devices are available from professional suppliers, but with some skill they can also be made at home, for example as tubes or mesh tunnels fitted over the entry gap.

“The principle is simple: bats fly out, cannot find their original opening when they return and seek alternative roosts – ideally bat boxes that have been provided in advance.”

Preparation is important:

• Watch at dusk for several evenings to establish exactly where the bats enter and leave.
• Record every access point; there are often several, sometimes only a few centimetres apart.
• Fit one-way devices in the late afternoon or early evening, when the bats are still in the roost but will soon leave.

Exclusion usually takes between three and seven nights. After that, there should be no further sounds or visible activity. If you are unsure, it is best to ask a specialist contractor or bat expert to confirm that the roost is genuinely empty.

Seal the gaps afterwards: close weak points thoroughly

Only once you are certain that no bats remain in the house should you move to the second step: sealing the access points. Otherwise, another colony may arrive next year, or a different animal may use the gaps.

Suitable materials include:

• Expanding foam insulation for fine cracks and joints
• Steel wool or copper mesh packed into medium-sized gaps before rendering
• Metal mesh for larger openings, vents and roof overhangs
• Door seals and specialist brush seals on loft doors
• Covers and caps for chimneys and ventilation pipes

Professional companies often offer guarantees that the treated areas will remain bat-free. In many cases, they also remove guano safely, using respiratory protection, disposable coveralls and low-dust working methods.

Keeping your home bat-free without harming bats

Anyone who has had bats before should be more vigilant in future. A brief inspection around the house before the spring “bat season” can make a major difference. Common weak points include:

• Junctions between the roof and the façade
• Loose or damaged roof tiles
• Soffits, eaves boards and bargeboards
• Joins between different building materials, such as timber and render

A powerful torch is useful: narrow gaps are easier to spot when the façade is lit from the side. If you find major damage, aim to repair it outside the summer months wherever possible.

Bat boxes: relocating rather than driving bats away

If there is sufficient space, you can provide the animals with an alternative. Special bat boxes can be fixed to external walls or freestanding poles at a height of around 4 to 6 metres. Sunny, sheltered south-east or south-facing locations usually work well.

These boxes can often house dozens of bats. They continue to provide natural mosquito control in the garden while reducing pressure on lofts and façades. There is no guarantee that bats will use them, but the chances increase where many bats are already active nearby.

What homeowners should also know

Many people fear bats, mainly because of rabies. In Europe, very few animals are actually infected. The overall risk is low, but the rule remains: never handle a bat with bare hands, particularly if it is on the ground or appears lethargic. In this situation, it is better to contact a wildlife rescue service, animal welfare organisation or bat expert.

Anyone planning refurbishment or conversion work, such as turning a loft into living space, should have the area checked early for bats. Where building work conflicts with species protection, specialists can usually find practical solutions, for example by providing replacement roosts, phasing the work and adapting lighting.

The animals also benefit homeowners: a stable bat population significantly reduces insect problems in the garden, mosquitoes around a pond and moths on the terrace. Making parts of the building bat-proof while offering roosts outdoors provides the best long-term combination of protecting the property and helping a threatened group of animals.