Research on bats and breathable membranes is being conducted by Stacey Waring at the University of Reading and the Bat Conservation Trust based upon the question ‘what constitutes a bat-friendly breathable roofing membrane?’
The research indicates that breathable roofing membranes are causing mass mortalities of bats in roofs, particularly during the breeding season. The membranes affect species which roost directly below the roof membrane (long-eared bats, horseshoes etc.) and bats which roost between the roof lining and the roof tiles (e.g. pipistrelle bats).
The problem with breathable membranes is that over time they give rise to loose fibres which bats can become tangled within. The research concludes that there are no bat-friendly breathable membranes on the market. As a result, Natural Resources Wales (in Wales) and Natural England (in England), will refuse bat licence applications which involve mitigation using roofs fitted with breathable membranes.
What does this mean for our clients?
Tyvek has not been accepted in bat mitigation licences for several years. Up until March 2013, a range of textured modern linings were accepted in bat mitigation licences but none of these are now accepted by the statutory agencies.
Non-breathable 1F bitumastic membrane is now the only roof lining that is accepted as being ‘bat friendly’.
Our licensed bat survey specialists are able to undertake all aspects of bat surveys including initial bat scoping surveys, dusk emergence and dawn re-entry flight activity surveys and remote monitoring. We have several years’ experience in the design and implementation of mitigation strategies for bats including the construction of bespoke bat roosts, bat exclusions and bat roost enhancement, as well as applying for European Protected Species licences for bats.