Introduction

Project description
A redundant timber-framed barn was converted into a residential dwelling, with a ceiling inserted at tie beam level. Although a loft space was integrated into the conversion, this was not part of a site-wide mitigation program as no EPS licence was obtained. This case study presents the findings of post-development monitoring work at a site where a brown long-eared maternity colony returned despite the absence of any specific mitigation.
Ecologist’s name and contact details
Patty Briggs
Planning authority
Dacorum Borough Council
Brief site description
A small, three-bay redundant listed timber framed barn within an area of open farm fields and woodland.

Pre-works roost structure

Type of structure
Building
Use
Agricultural Building
Condition
Derelict
Approx. age
18th century
Main construction material of walls
Timber
Roof design
Pitched Roof
Roof material
Clay Tiled
Internal roof structure
Timber Frame

Pre-works roost description

Species
Brown long-eared bat
Number of bats max count
25
Type of roost
Maternity Roost
Evidence of bats
Droppings Visual
Roost location
Other
Aspect of roost
Other
Height of roost entrance (m)
Not known
Roost material(s)
Nearest commuting feature
Hedge
Distance to nearest commuting feature (m)
Not known

Proposed works

Description of works
A redundant timber-framed barn was converted into a residential dwelling with a ceiling inserted at tie beam level. Although a loft space was integrated into the conversion, this was not part of a site-wide mitigation program as no EPS licence was obtained. This case study presents the findings of post-development monitoring work at a site where a brown long-eared maternity colony returned despite the absence of any specific mitigation.
The roof space height was 3m with a width of 5.5m and length of 11m. This provided a roof space with a volume of 90.75m cubed. Traditional tiles with conventional bituminous roofing felt were used.
Type of impact upon the roost
Disturbance

Monitoring data

Length of monitoring proposed
None proposed
Frequency of monitoring
Single monitoring inspection completed.
Type of monitoring
Roost Inspection
Evidence recorded
Visual count of bats was 20 brown long-eared bats.
Interventions made
None reported

Final details

Lessons learned
This conversion should never have been carried out without consultation with the SNCO. The work should have been carefully programmed to avoid sensitive periods of the year. This could possibly have affected the colony size. The work should have been supervised. This conversion took place before the introduction of EPS licenses which would have addressed all these issues.

The bats had access to a large, warm, dark loft space. It is unusual for Planning Authorities to allow a ceiling to be inserted at tie beam level throughout the whole barn. This would not usually be allowed in a listed barn.

Conversion of a barn into a residential dwelling done without any prior bat survey work. It was only by luck that the design of the conversion retained a large loft area that bats could access at a gable end.