Managing smell

It is not common for bat roosts to cause an issue with smell, however on occasion, an odour can develop due to an accumulation of bat droppings within the space where the bats roost, such as a loft space, wall cavity or roof crevice. It is usually a seasonal issue, being most discernible in the summer months when the bats are present and when the weather is warmest.

Droppings themselves rarely smell (as they are made up of dried insect remains), but an odour may occur if droppings come into contact with moisture, or where an accumulation of droppings are present in a poorly ventilated area.

Clearing up droppings

If the droppings are easily accessible e.g. on the floor of a loft space, we would recommend clearing out any accumulations in the autumn to help eliminate any odour. We advise that droppings are cleared in September/October each year (not during the summer or winter) to avoid entering the space when bats are most vulnerable to disturbance.

If you cannot clean up the droppings yourself, you might consider asking a friend or relative for help. Alternatively, you may wish to hire a cleaner or similar contractor. Provided that the droppings are cleaned when the bats are absent (usually between September – April), the person cleaning the droppings will not require a licence or specialist bat knowledge.

On extremely rare occasions there are health risks from allergic reactions and dust inhalation (e.g. if cleaning up very large quantities of droppings). Therefore we always suggest maintaining basic standards of hygiene by wearing a dust mask and washing your hands after handling any droppings.

A layer of paper (e.g. newspaper or brown wrapping paper) or cloth sheeting (e.g. dust sheets) can be put down under the main roosting areas as a cheap and easy way to clean the droppings out in the future. You can simply roll up the paper/sheeting and then place the droppings in the bin or add to your compost or flowerbeds - bat droppings make a good fertiliser so can be added to the garden! Items stored in the loft can also be covered to keep them clean. Some roost owners have found that placing a tray of cat litter under the main roosting areas to help collect droppings and reduce smell can be useful too.

Plastic sheeting should be avoided where there is a risk of condensation as this can make the droppings damp and cause smell.

Odour-eliminating solutions

There are also a few odour eliminating solutions on the market you may wish to try that can help to reduce any lingering smell in the rooms affected.

Here are a few examples;

  • Placing a tray of activated charcoal in the room.
  • This blog contains a handy step-by-step guide to using activated charcoal to neutralise areas affected by strong odours.
  • Please also find further information regarding activated charcoal, detailing how it works to eliminate odours in your home
  • Using an odour-absorbing spray (e.g. Envofresh).

Odour removing bags have also been used successfully where there is a large bat roost. These are non-toxic and biodegradable and remove odour within 24 hours. These can be used in the loft space and/or in the affected rooms. An example product is, ‘Earth Care Odour Eliminating bags’.

If the smell issue is not possible to resolve on your own e.g. if the droppings are inaccessible or if the smell is still intolerable after trying the above odour reducing solutions, please go to the 'What to do if the issue persists' page.

This advice provided by the National Bat Helpline is only possible thanks to the generosity of people like you. Our vital advice service helps thousands of people by providing advice for free, this in turn saves thousands of bats every year. Partial funding from Natural England helps cover some of our running costs, but it does not cover everything. Your donation will help ensure our small team can continue to provide assistance and a lifeline for bats.

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