Introduction

Project description
Full restoration of a Grade I listed building and a series of historic barns, regarded by Cadw as one of the finest medieval hall houses in Wales. The site was originally surveyed in 2014 with seven species of bat identified as being present, including lesser horseshoe, brown long-eared and Natterer's.
Ecologist’s name and contact details
Richard Dodd, rdodd@wildwoodecology.com, Wildwood Ecology
Client’s name
The Landmark Trust
Planning authority
Brecon Beacons National Park Authority
Brief site description
Located in the Llanthony Valley on the edge of the Brecon Beacons National Park, Llwyn Celyn is regarded as one of the most remarkable of all surviving late-medieval houses in Wales. The site comprises of a Grade I Listed Farmhouse, with associated agricultural buildings including a Grade II Listed stone barn (Beast House), stone Threshing Barn and Cow Shed, a smaller stone Drying Shed and a series of modern agricultural sheds. It was built in 1420 on the lands of the Llanthony Priory and is a very rare survival from so soon after the destruction caused by Owain Glyn Dŵr’s Rising against the English Crown. Possibly a prior’s house, Llwyn Celyn is rich in rare medieval features and has barely changed since around 1690.

Pre-works roost structure

Type of structure
Building
Use
Domestic Dwelling
Condition
In Use
Approx. age
1420 (600 years old)
Main construction material of walls
Stone
Roof design
Various
Roof material
Stone
Internal roof structure
Timber Frame
Lighting present on site and its proximity to the roost
A small 'welcome' light set away from access point. Minimal site lighting due to location within the National Park.
Photos or annotated figures of roost structure

Pre-works roost description

Species
Lesser horseshoe bat
Number of bats max count
18
Type of roost
Satellite Roost
Evidence of bats
Bats Seen in Roost
Roost location
Other
Aspect of roost
Various
Height of roost entrance (m)
3m
Roost material(s)
  • Timber Roof Frame
Nearest commuting feature
Hedge
Distance to nearest commuting feature (m)
5
Internal temperature and humidity of roost
various
External temperature and humidity of roost
various
Nearest artificial light source to roost
250m to the northeast - street lighting
Nearest artificial light source to roost commuting route
250m to the northeast - street lighting
Photos or annotated figures of roost

Proposed works

Description of works
Extensive repairs and renovations across the Llwyn Celyn site to:  Restore the main house to a habitable condition, to be used as holiday accommodation by the Landmark Trust;  Restoration of the beast house, with creation of public information area and viewing mezzanine;  Restoration and conversion of the threshing barn into bunk-house style accommodation and facilities;  Repair to the cowshed, to house heating equipment for the site and an outdoor store;  Repairs to the drying shed; and  Demolition of the Dutch barn, tin shed, and pole barn.
Type of impact upon the roost
Long-Term Roost Modification and Roost Loss

Proposed mitigations

Type of mitigation
Avoidance
Specific technical detail of measure
Mitigation design was by Richard Crompton and Bob Firmin. A variety of roosting spaces for lesser horseshoe bats were created within the new 'cider house' and 'link building' to the rear of the main house. The whole link building, and the first floor of the cider house were set aside as dedicated bat roosts. Thermal and sound insulation was installed at ceiling level of the bedroom and bathroom. Dedicated bat access was provided above the old blocked doorway in the north-west gable wall of F12a. An opening measuring 400mm (w) x 200mm (h) was created suitable for use by lesser horseshoe bats, as high above ground as possible. This was in the form of a simple vent with sloping stone tiles to help minimise the ingress of wind driven rain as the opening is westward facing. A single baffle was installed within the roof space to minimise light and draughts within the bat roost – constructed from sterling board/OSB or similar and was extend down 1m from the top of the roof located 1m in horizontally from the gable wall. The outward facing surface was painted matt black to minimise light reflection.
Relevant annotated figures
Roost location
Bat House
Aspect of roost
W
Height of roost entrance (m)
2
Roost material(s)
  • Bitumen Felt
  • Slate Tiles
  • Stone
Nearest commuting feature
Hedge
Distance to nearest commuting feature (m)
5
Nearest artificial light source to roost
20m (PIR security light)
Nearest artificial light source to roost commuting route
20m (PIR security light)
Photos or annotated figures of roost

Monitoring data

Length of monitoring proposed
5
Frequency of monitoring
Two bat activity surveys per year between the period May 15th to August 15th for the first five years following the year of implementation of the development; b. an annual inspection of bat mitigation measures in October for the first five year following implementation of the development;
Type of monitoring
Dusk and Dawn Survey
Date and time
1st August 2018 14:00
Evidence recorded
27
Interventions made
Reduce light in roost with additional boarding
Type of monitoring
Dusk and Dawn Survey
Date and time
1st August 2019 14:00
Evidence recorded
66
Type of monitoring
Dusk and Dawn Survey
Date and time
14th May 2018 14:00
Evidence recorded
16
Type of monitoring
Dusk and Dawn Survey
Date and time
13th May 2019 14:00
Evidence recorded
17
Type of monitoring
Roost Inspection
Date and time
11th May 2020 14:00
Evidence recorded
25
Interventions made
Remove jackdaw nest from interlink building

Final details

Lessons learned
Llwyn Celyn’s restoration took almost three years on site, and required the full range of professional and traditional craft skills. Everyone ensured that the project was successful and working with the project manager and contractors was key, alongside frequent site visits. There were many challenges from working on such a historic building and those needed to be reflected with a large dose of pragmatism from the ecology team and liaising with NRW. This was the weak point, with delays in responses and significant restrictions put in place that caused significant delays at the start of the project. Communication has therefore been key in getting this £4M project through to completion and onward monitoring. Covid 19 restricted us to one visit in May 2020, with no second visit in August 2020, where numbers of lesser horseshoe are usually higher, but last years numbers were very encouraging and significantly greater than the 18 bats found during the first visits back in 2014. A pleasure to work on! With considerable thanks to Richard Crompton and Bob Firmin.