Bat bricks, bat tubes and bat boxes all do the same basic job: they give bats a sheltered space to roost in where there are few natural roosting sites left. The difference is where they go. A bat brick or integrated bat box is built into the wall of a building as it goes up, while an external bat box is fixed onto a wall, post or tree afterwards. Below are the main types, the placement rules from the Bat Conservation Trust (BCT) and council specifications, why planning conditions ask for them on new homes, and the licence rule that applies once bats move in.
What are bat bricks, bat tubes and bat boxes?
The BCT describes bat boxes as artificial roosts designed to encourage bats into areas where there are few roosting sites. Designs range from wooden boxes you can make yourself to ready-made external boxes and integrated boxes built into walls. Different bat species need different spaces, so there is no single right box for every site.
| Type | What it is | Where it goes | Upkeep |
|---|---|---|---|
| Bat brick (integrated bat box) | A roost chamber built into the outer face of a wall and matched to the surrounding brickwork | New builds, extensions and rebuilt walls, laid in as the wall goes up | Generally none for designs that let droppings fall out |
| Bat tube or bat block | An integrated unit built into the wall fabric; its opening leads only to a self-contained roost chamber | New walls, following the manufacturer's installation guidance | Generally none for self-cleaning designs |
| Ridge roost unit | A roost unit fitted at a ridge end, giving space for small numbers of crevice-dwelling bats | Roofs, during new build or renovation | Follow the manufacturer's guidance |
| External bat box | A ready-made box screwed onto a building or nailed or strapped to a tree, often made of woodcrete or a similar blend | Existing houses, outbuildings, mature trees and bespoke posts | Leave alone once fitted; boxes that trap droppings need cleaning by a licensed ecologist |
| Wooden bat box | A cubic or wedge-shaped box of rough-sawn, untreated timber with a narrow slit and a grooved landing area | Gardens, trees and walls | Less durable than woodcrete |
How integrated bat boxes differ from external bat boxes
Integrated bat boxes are built "into" a building; external boxes are fixed "onto" it. That one difference drives most of the practical trade-offs.
| Permanence | The BCT says integrated boxes give bats a secure, permanent space. Leeds City Council's guidance adds that boxes fixed onto a building are more likely to be removed by future householders. |
|---|---|
| Maintenance | Integrated boxes need little maintenance. Boxes on trees are more prone to vandalism and need more upkeep, and a tree fixing may need adjusting every few years as the tree grows. |
| Temperature | Integrated boxes may have better thermal properties because they sit within the wall. Any box should be draught proof and made of a thermally stable material. |
| Appearance | A bat brick sits flush and can be matched to the facade. Some integrated units can be rendered or painted with breathable paint, if the manufacturer's guidance allows it. |
| Existing buildings | External boxes can go up on an existing house, outbuilding or tree at any time. Integrated units are mostly built in as a new wall or roof goes up. |
| Access to the house | Bat bricks and bat tubes open into a self-contained chamber, so bats cannot get from the box into the inside of the building. |
Which bat roost feature suits your project?
| Your situation | Usual choice |
|---|---|
| New house, extension or rebuilt wall | An integrated bat brick, bat tube or bat block, located by the ecologist and shown on the plans |
| Existing house you want to make bat friendly | One or more external bat boxes high under the eaves on a sunny elevation |
| Garden with mature trees near a hedgerow | Woodcrete tree boxes, several to a tree, facing different directions |
| Planning condition for biodiversity enhancement | The number, type and location set out in the approved plan, installed before the home is occupied |
| Work that will affect an existing roost | Mitigation designed by a licensed ecologist; new boxes alone do not replace a lost roost |
Bat box materials: woodcrete, concrete and timber
Woodcrete is a mixture of concrete and wood, and woodcrete boxes are more durable than wooden bat boxes. External woodcrete boxes come as cylinders with a side entrance, designed to hang on a tree, or brick-shaped boxes with an entrance underneath for trees or walls. The BCT notes a growing number of durable alternatives to wood, and Cotswold District Council's biodiversity specification for developments asks for external and tree boxes made from woodcrete or a similar blend for durability, stating that wooden boxes are not suitable.
Bat bricks and blocks are made to be matched and built into the walls and facade of a building, so the specification depends on the brick, block or cladding being used. Leeds City Council's guidance asks the ecologist to confirm with the architect that the roost feature suits the building materials.
Timber still works for a garden box if it is built the way the BCT recommends:
- rough-sawn (unplaned) wood, because bats need a rough surface to cling to
- no wood treatment, because bats are very sensitive to chemicals
- an entrance slit usually 15 to 20 mm wide, too narrow for predators
- a grooved "bat ladder" or landing area leading to the slit
- well-sealed joints, no removable lid and no large loose front panel
If you do paint or treat a box, the BCT says to do it before the box goes up so it dries fully, treat the outside only, and leave the landing board bare.
Bat box placement: height, aspect, light and flight paths
Bat boxes are more likely to be used where bats already feed. Good bat box placement is mostly about warmth, safety from predators and darkness.
| Height | The BCT says ideally at least 4 m above the ground where it can be installed safely, and as high as possible to reduce predation by cats. Cotswold District Council's specification sets 3 m as a minimum, and Shire Group IDB guidance suggests around 5 metres on trees. |
|---|---|
| Aspect | Boxes should get some sun during the day, usually from the south, south-east or south-west. Put up several boxes facing different directions so bats can choose a warmer or cooler roost. |
| Shade | Boxes that are shaded are likely to be too cold for bats. On a deciduous tree, think about summer leaf cover before you fix a box in winter. |
| Artificial light | Keep boxes away from artificial light, which exposes bats to predation. Cotswold's specification keeps entrances at least 2 m from windows and 5 m from external lights. |
| Clear flight path | Keep the entrance unobstructed. Cotswold's specification keeps it at least 0.5 m from eaves, branches or ledges to reduce predation risk. On new builds, avoid placing roost features above windows or doors. |
| Shelter | The BCT asks for shelter from strong winds. On an exposed coastal site in East Durham, choose the sunny elevation that is least battered by the wind. |
| Navigation | Bats use dark tree lines or hedgerows for navigation, so a box near these is easier for bats to find. |
| On buildings | The BCT advises fixing boxes as close to the eaves as possible, high on a wall that gets sun for part of the day. |
Placing bat bricks on a new build
On a development, the ecologist decides where integrated features go. Leeds City Council's guidance lists the considerations as the height of the feature, the aspect of the building, avoiding external lighting and having no windows or doors below. Durham County Council's Biodiversity SPD asks the appointed ecologist to set the type of box, its location and aspect, and its links to landscape features, and to show bat, bird and bee boxes on the landscape, site or elevation plans. During construction, the entrance must be kept clear of construction debris.
Bat bricks and bat boxes in planning conditions
Councils ask for bat bricks because new homes have stopped providing roosts. The BCT explains that changes to the building regulations to cut carbon have moved homes from ventilated roof spaces to airtight construction, so low and zero-carbon buildings give bats no access to the roof space. Durham County Council's Biodiversity SPD (April 2025) makes the same point and asks for roosting and nesting places to be built into new buildings, with boxes fixed to external walls where that is not feasible. GOV.UK's planning practice guidance on the natural environment encourages features that support species such as swifts, bats and hedgehogs.
| Durham Biodiversity SPD: suggested features | Number |
|---|---|
| Residential schemes, small and large | At least 50% of new dwelling buildings with an integral bat roosting feature and/or swift brick |
| Large buildings such as schools, industrial buildings and hospitals | 10 to 20 features |
| Bat and bird boxes not on buildings | Best on existing mature trees or bespoke posts, not new tree stock |
The same SPD asks for bee bricks in developments too. Conditions can work in two stages. Leeds City Council's published wording, for example, requires a plan from an ecologist showing the number, specification and location of integral bat roosting features and swift bricks before work starts, then a report with photographs confirming they were installed before the homes are first occupied. Features must be retained afterwards.
This kind of habitat enhancement is not the same as the bat mitigation planners ask for when a survey finds a roost. If a roost will be destroyed, GOV.UK's guidance for planning decisions says there must be no net loss of occupied and unoccupied roost sites and that roost types are replaced like for like, which an ecologist designs and a licence covers.
Bat boxes and biodiversity net gain
Biodiversity net gain (BNG) has been mandatory in England since 12 February 2024, with developers required to deliver a 10% gain. Exemptions apply, and from 6 August 2026 they include planning applications for sites of 0.2 hectares or below. The statutory biodiversity metric measures the biodiversity value of habitats, and Durham's SPD is explicit that species-based features such as bird and bat boxes are not included in the metric. They are still encouraged as additional enhancements for wider biodiversity, alongside the habitat units a scheme has to deliver.
What the British Standard BS 42021:2022 covers
BS 42021:2022, Integral nest boxes: Selection and installation for new developments: Specification, was published by BSI on 31 March 2022. It covers integral nest boxes for birds in new buildings, naming swift, starling, great tit, blue tit and house sparrow, and it excludes exterior bird boxes. It does not cover bat roost features, and councils that ask for both, such as Durham, list an integral bat roosting feature and a swift brick as separate items. For bats, the placement detail comes from BCT guidance, the council's own specification and the manufacturer's installation instructions.
Once bats move in: checking a bat box needs a licence
All UK bat species and their roosts are protected by law, and a roost is protected whether or not bats are in it at the time. The BCT is clear that once bats have used a box, it can only be opened, moved or disturbed by someone with the right licence, all year round, even if bats only use it for part of the year. In England, Natural England's level 1 class licence (CL17) lets registered bat workers cause reasonable disturbance to confirm whether bats are in a bat box, and a level 2 licence is needed to handle bats when checking boxes.
You can check for use without a licence from outside the box:
- look for droppings and urine staining below the entrance
- from May to September, listen for chattering on warm afternoons and evenings
- watch the box for an hour either side of sunset for bats leaving to feed
Be patient. The BCT says it may be several months or even years before a box has residents. Your local bat group can sometimes confirm whether a box is in use; if it cannot help, you may need an ecological consultant.
Common mistakes with bat bricks and bat boxes
- Facing the box into shade. A shaded wall or a box under dense summer leaves is likely to be too cold for bats.
- Fitting it near a light. Security lights, floodlights and lit windows near the entrance expose bats to predators.
- Mounting it too low. Below about 3 m, or beside a ledge or branch, cats and other predators can reach it.
- Blocking the entrance on a new build. Construction debris left in the entrance stops bats getting in.
- Treating or planing a wooden box. Bats need rough, untreated timber inside.
- Fixing boxes to newly planted trees. Mature trees or bespoke posts work better than new tree stock.
- Opening the box to look. Once bats have used it, that needs a licensed bat worker.
- Treating boxes as a replacement for checking a building. If a loft conversion, re-roof or demolition could affect bats already in the building, the council will want a bat survey first, and a new box does not replace a roost that is lost.
The BCT does not recommend any one product, noting that comprehensive monitoring data is still lacking. Placement, rather than the brand on the box, is what you control.
