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The Barn Owl Trust

Conserving the Barn Owl and its Environment

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Accommodating Barn Owls within building projects

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Is it worth doing at my site?

The chances of getting Barn Owls to roost or nest at your site depends on the suitability of the landscape and on the suitability of the owl hole and nesting space that you provide. If your site is in a rural area, not within 1km of a motorway or similar fast road, not in high mountains, and not obscured by tall trees or buildings then it is probably suitable. Click here for a description of ideal foraging habitat. Click here for a map of Britain showing the suitability of each 1km square. Remember that Barn Owls forage over huge areas (350 to 5,000 Ha) and so even if the fields surrounding your site are not ideal Barn Owls may still roost or nest.

Is my building suitable?

The minimum recomended height for an owl hole, nestbox, or built-in nest space is 3 metres (10'). The hole will need to be spotted by chance so it must be as visible as possible. A suitable building will be tall and the owl hole will be visible from nearby fields. Design requirements (including measurements) for creating the owl hole and nesting space are provided below.



Useful background information

With a bit of careful planning and a modest amount of building work a Barn Owl nesting place can easily be incorporated into almost any large rural building. It is now fairly common for barn conversions to include provision for Barn Owls and you could even consider creating a small space for Barn Owls in the roof of your own house! Barn Owls are surprisingly tolerant of regular noise and activity around their nest or roost site; once familiar to the birds, regular comings and goings pose no threat. Even rural industrial units can be potential nest sites if provision is made.

There's more information on this topic in the Barn Owl Conservation Handbook


In spite of the fact that they are a protected species, Barn Owls used to be afforded little or no consideration within the planning system and until quite recently unsympathetic barn conversions frequently resulted in the loss of nesting sites. However far from being the worst-case scenario, barn conversions can be a potential lifeline, which, if undertaken correctly, can safeguard traditional Barn Owl sites for future generations. Contrary to popular belief, the presence of Barn Owls is never an obstacle to planning consent as long as their needs are catered for.


The idea that the needs of Barn Owls can be catered for simply by erecting a nestbox on the nearest tree is very short-sighted and quite frankly inadequate. Such boxes will only last 10-15 years and cannot possibly be considered as adequate compensation for the loss of traditional nest sites.

We therefore strongly recommend the creation of permanent provision within the roof space of a dwelling or other building in order to ensure that such sites remain available to Barn Owls for at least a hundred years.


So, whether it’s a barn conversion, a farmhouse renovation, a new industrial unit, a new dwelling, or even a new housing estate, if it’s in the countryside why not make provision for Barn Owls? These beautiful birds are a unique natural asset and an indicator not only of the health of the countryside but of the enlightened times we live in. The cost of creating provision is negligible and as long as it’s done properly there are no health or nuisance implications. If a few simple rules are followed Man and Barn Owl can live successfully side-by-side.


Design requirements

If you are planning to develop a site that has evidence of Barn Owl occupation (either current or within the past 2 years), you will need to create temporary alternative provision within 200m as soon as possible and at the very least 30 days before any works commence.

For more information please read the section entitled “Making Provision for Barn Owls” in the guide called “Barn Owls and Rural Planning Applications” (click link >)

Adhering to the following criteria will ensure the creation of a safe, permanent area for Barn Owls in the roof space of a dwelling or other building;

- Entrance hole: minimum size 100mm wide x 200mm high, optimum size 130mm W x 250mm H, maximum size 200mm W x 300mm H.

- Floor area of nest chamber: absolute minimum 0.4m2, ideal size is 1m2 (These dimensions are bigger than those for nestboxes because built-in provision usually lacks external exercise areas that would permit maximum wing stretching prior to fledging).

- Depth from bottom of entrance hole to floor of nesting area must be not less than 460mm.

- Interior must remain dry during prolonged heavy rain coming from any direction.

- Human access for easy clearing-out of nest debris is essential (probably once every 3-4 years or less).

- Measures aimed at reducing the chances of entry by other species (such as Jackdaws) are to be encouraged provided that they do not significantly reduce the box's suitability for Barn Owls.

- Should be substantially constructed and well-insulated against condensation and noise.

- Should not be constructed from tropical hardwood unless the timber is certified as sustainably grown (FSC).

- Hipped roofs, and pitched roofs where optimal siting of the access is through the roof rather than the wall/gable end, will require the use of a specially built miniature dormer or owl-hole ‘tile’.

- Where the access is in a vertical structure such as a wall or gable end, there should be an external landing platform or perch below the entrance hole to facilitate the Barn Owls’ arrival and departure.

- Owners of buildings with permanent provision in the roof space should also be aware of the following subjects: foraging habitat requirements, the need for clearing out debris so as to maintain internal depth, what to do if a young Barn Owl is found and human safety issues

The Barn Owl Trust is dedicated to conservation & education and does not operate a visitor centre.
Barn Owl Trust staff and volunteers
Waterleat, Ashburton, Devon TQ13 7HU
+44 (0) 1364 653026