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The ecologist’s report is on your desk. It calls for “bat access tiles”, and the roofer needs to know what to order. The roof schedule gives you the slate size and pitch. It says nothing about how wide the entrance should be or where the bats need to go once they’re through it.
Start with the drawing that shows the roost. Read it alongside the mitigation strategy and any licence. Between them, those documents should give you enough to specify the number of tiles, their position, the entrance dimensions and the route into the roost. Here’s how to turn those details into an order.
If you’ve only just discovered bats and are still working out what that means for the project, start with What Happens if I Have Bats in My Roof?
Why Your Bat Access Tile Specification Matters
Planning conditions
A local planning authority can make bat mitigation a condition of planning permission. Read the decision notice for both the deadline and the evidence the council wants. You may need to discharge a condition before anyone occupies the building, sometimes by submitting photographs of the completed work. Other conditions bite much earlier. On a scheme in Cuffley, for example, the council wanted the location and specification of two bat features approved in writing before building work went above ground. Cuffley mitigation proposal · Example of a pre-occupation condition
Bat mitigation licences
In England, a project that needs planning permission will normally need that permission in place before Natural England issues a bat mitigation licence. The usual routes are a project-specific European protected species (EPS) mitigation licence or, for eligible work, a class licence through a registered consultant. Any access features required by the licence are legally binding. Natural England’s planning guidance · Bat mitigation licensing guidance
If your report refers to the low-impact class licence, CL21, check the programme with your ecologist. Existing registered consultants can register new sites under CL21 until 14 December 2026. Natural England is replacing it with the Bat Earned Recognition class licence, CL47. Natural England’s CL21 guidance
In Wales, bat licensing sits with Natural Resources Wales, and in Scotland with NatureScot. In the Republic of Ireland, the National Parks and Wildlife Service handles derogation licences.
What happens if the mitigation isn’t delivered?
In 2023, Natural England prosecuted a Derby developer over a housing scheme near Ashbourne. One of four licence breaches involved missing access tiles and ridge crevices specified for the roof. The developer pleaded guilty and was ordered to pay £14,435.17 in total, including a £3,200 fine, a surcharge and prosecution costs. Natural England’s account of the case
How to Read an Ecologist’s Bat Access Specification
Number and position of access points
The ecologist sets the number of entrances and marks their positions. Where an entrance replaces one the bats already use, the aim is usually to keep it as close to the original as possible so returning bats can find it.
Look for the aspect (which way the roof slope faces) and the height of each entrance. A note such as “south-facing slope” tells only half the story. On the Cuffley drawing, the ecologist placed two access slates just below the ridge, one either side of the centre line. That’s the level of detail your roofer needs. Cuffley roof drawing and specification
Entrance gap dimensions
Read the measurement as the clear opening available to the bat. Published schemes show how much that can vary.
- At Millbrook House in Abbeyleix, the ecologist called for a 15–20 mm gap into the coach house roof. Millbrook House technical note
- At Dovecote Cottage in Norfolk, one proposed option was a 20 × 50 mm gap beneath the ridge tiles. Dovecote Cottage appraisal
- At Cuffley, the specified slate unit had an entrance 20 mm high by 100 mm wide. Bat access slate specification
There’s no universal gap size. If a supplier offers a “20 mm bat tile”, you know the height. You still need the width before you can tell whether it matches your drawing.
Where the access leads: under the tiles or into the roof void
For a crevice roost, the bat may only need to reach the narrow space between the underside of the tiles and the roofing felt. A loft roost needs a route through the roof covering and underlay into the void itself. From outside, the two entrances can look much the same. If the drawing only shows the roof elevation, ask the ecologist to confirm where the route ends before you order. Bat Conservation Trust guidance on roost spaces
Does the Species in Your Report Change the Tile?
Crevice-dwelling and roof-void bats
Pipistrelles can crawl through a gap roughly the width of a thumb and roost beneath the tiles. Brown long-eared bats can also crawl through a small entrance, but often use the open loft beyond it to fly. A standard bat access tile can serve either species where its opening and the space behind it match the ecologist’s design. Bat Conservation Trust guidance on bats in buildings
Horseshoe bats
Greater and lesser horseshoe bats generally fly straight into their roosts. Both occur in South West England. If the report names either species, look for a dedicated fly-in opening on the drawings. Even a large-profile bat tile gives too little clearance for that flight path, so the ecologist will specify a different feature. Bat Conservation Trust guidance on access · Greater horseshoe distribution · Lesser horseshoe distribution
Choosing a Bat Access Tile for Your Roof Covering
Leadworx makes two sizes. Compare the first three measurements with the ecologist’s detail. The last two give the size of the lead flashing that sits against the surrounding roof covering.
Measurement | Standard | Large profile |
Access height | 20 mm | 40 mm |
Access width | 180 mm | 200 mm |
Access depth | 140 mm | 150 mm |
Flashing width | 320 mm | 500 mm |
Flashing depth | 300 mm | 450 mm |
Natural slate and plain tiles
For natural slate and plain-tiled roofs, start with the standard unit. Its access is 20 mm high and 180 mm wide. That width matters if, for example, the report calls for the 20 × 100 mm entrance in the Cuffley scheme. The heights match, but the standard unit gives a wider opening. Standard Bat Access Tile
Large profile and interlocking tiles
On a deeply profiled or interlocking roof tile, the shape of the covering determines how the flashing sits. The large-profile unit gives the roofer a wider, deeper flashing to accommodate that shape. It also doubles the entrance height to 40 mm, so check both the tile profile and the permitted gap. Bat Access Tile for Large Profile Tiles
Roof pitch
Give the supplier the pitch in degrees for the slope that will carry the access tile. A dormer or later extension can have a different pitch from the main roof. If the drawing gives only rise and run, use How to Measure a Roof Pitch.
When a bespoke size is needed
A bespoke unit makes sense when the ecologist specifies a different opening or the roof has an unusual covering. Reclaimed tiles, for instance, can vary in thickness and curve even within one course. A roofer can dress Code 4 lead to those variations. A rigid unit needs to match the profile as supplied.
For a quote, send the supplier the entrance dimensions, roof pitch and a side-on photograph of the covering. The 3D models show where each measurement is taken. Standard tile 3D specification · Large-profile tile 3D specification
Lead, Plastic or Clay: Bat Access Tiles on Heritage and Conservation Roofs
On a listed building or a prominent roof slope in a conservation area, settle the appearance early. Show the conservation officer the proposed unit alongside the existing covering. A side view helps them judge how far the hood will stand proud of the roof. For a listed building, check whether the change needs listed building consent and what any existing consent says about materials. Historic England guidance on listed building consent
Lead is a good fit where the roof already has visible leadwork or the courses are uneven. It weathers to a soft grey, and the flashing can follow the contours of old tiles. Leadworx uses 100% recycled Code 4 sheet lead for its bat tiles. Well-detailed lead flashing can last 60 to 100 years or more, depending on exposure and workmanship. How Long Should Lead Flashing Last?
Plastic can be a practical, lower-cost choice on a regular roof where the manufacturer offers the right profile and colour. On weathered clay or slate, ask to see a sample. A close colour match on screen can still look quite different in daylight. Plastic generally has a shorter service life than lead, and recycled content varies by product. Ask for the manufacturer’s figures if either is part of the specification. Lead vs Plastic Roof Vent
Integrated clay or slate is often the best choice when an exact visual match matters most. A clay access set in the same colour and camber as the surrounding tiles can be particularly discreet on a street-facing slope. Natural slate offers a similar advantage on a slated roof. Both materials can give long service. With reclaimed coverings, compare an actual sample for thickness, texture and weathering before agreeing the match. Society for the Protection of Ancient Buildings guidance on clay tiles · Example of an integrated clay access set
Bat Access Tiles and Roofing Membranes
Check the felt or membrane while the roof specification is still being written. Bats using the space beneath the tiles can come into direct contact with it, and their claws can draw loose fibres into loops that catch them.
In England, a bat mitigation licence application proposing a non-bitumen-coated roofing membrane in the roost must include a certificate showing that the product passed a snagging propensity test. Natural England exempts bitumen 1F felt with a non-woven, short-fibre construction from that certificate requirement. Give the ecologist the exact product name before ordering. A merchant’s description of “breathable felt” is too broad to establish whether the membrane meets the licence requirements. Natural England’s roofing membrane requirements
Bat Access Tile FAQs
Can a bat access tile be made to a specific gap size?
Yes. Leadworx fabricates bespoke sizes to order. Give the supplier the clear entrance height and width from the ecologist’s detail, together with the roof covering and pitch. Leadworx bat access tiles
Who decides how many bat access tiles I need?
The named ecologist sets the number and positions in the mitigation strategy or licence. If the roof plan and the written schedule give different quantities, ask the ecologist to confirm which to order.
Can I use a different tile from the one in my report?
Check with the named ecologist first. Send the proposed tile’s drawing so they can compare the clear opening, position and route into the roost. If the change affects an approved planning detail or a licence condition, get the necessary written approval or licence amendment before substituting it. Natural England’s guidance on changing a bat mitigation licence
