Row erupts over 'bat safe' roofing membrane 3

Row erupts over ‘bat safe’ roofing membrane

A row has broken out over a bat-friendly roofing membrane which has been promoted as safe for the protected mammals for almost three years.

The company which makes the membrane – TLX Insulation – has used conservation organisation’s logos without their permission in some marketing materials, and claimed its product has passed a “bat friendly test” which researchers claim does not currently exist.

TLX Insulation, which started selling the ‘bat safe’ roofing membrane in January 2019, insists it allows roofing contractors and builders an alternative to the existing breathable membranes – which can be dangerous to bats – whilst still allowing roofs to breath. 

Problems can occur with breathable roofing membranes, also known as non-bitumen coated roofing membranes, when they become worn. These issues have resulted in significant numbers of bats getting their claws tangled in the fibres and dying of starvation according to research from Stacey Waring at Reading University. The wear to membranes can happen in as little as six months.

Photo by Davog McCloskey

Bats are a protected species and it is a criminal offence to intentionally capture, injure or kill a bat or disturb a bat in its roost. As a result the non-bitumen coated membranes were banned in known bat roosts.

This, claims TLX Insulation, prompted the company to develop a more durable ‘bat friendly’ breathable membrane. The TLX BATSAFE Breather Membrane was patented in 2018 and the company recommends its use to line roofs, where it comes into contact with bats which like to roost under slates and tiles, above wall heads and in attics.

The firm says its product passes a ‘bat friendly test’ designed by Waring. However, writing on social media, she claimed that the test was just one potential aspect of whether a product could ever be deemed suitable in the future. 

“TLX BATSAFE has not passed a ‘bat friendly’ test. They [TLX Insulation] have conducted a single test which was based on parameters from some of my data,” she wrote. “The test is not a ‘bat friendly test’ nor is it accredited or approved as such by BCT, NE or any other body involved in bat conservation.”

NatureScot, Natural England and Natural Resources Wales – statutory nature conservation organisations (SNCOs) that work independently of their respective governments – also confirmed the TLX BATSAFE membrane is not recognised as a safe option in bat roosts.

We [NatureScot] are unaware of any evidence that bats have been contaminated by bitumen, although it is theoretically possible in the extreme lab conditions suggested in the video.


Bat licenses can be granted by the SNCOs to conduct “an activity that would otherwise be illegal” – such as removing or repairing the roof of building with a known bat roost –  as long as certain conditions are met. Bat licences for roofing projects will not be granted where the TLX BATSAFE membrane is used, they claimed.  

Despite this TLX insulation sent a marketing email to UK professional bat consultants in June 2021 claiming that the TLX BATSAFE membrane can be safely used where bats are present.

It also claimed it had passed the Bat Conservation Trust (BCT) tests which had been conducted in conjunction with the University of Leeds. At the time the company’s website was prominently displaying the logos of both organisations.

Row erupts over 'bat safe' roofing membrane 4
Photo by John Martin

A spokesperson for BCT said it was unaware its logo was being used by the company. “I have contacted them and asked for it to be removed,” they added. “We do not endorse products or refer to a product as bat friendly.” 

The test referred to in the email – and on TLX Insulation’s website – was published in May 2020 and co-authored by BCT, the three SNCOs, University of Leeds and University of Reading. 

Steven Russell, professor of textile materials & technology at the University of Leeds was one of the co-authors. “The University of Leeds does not endorse the TLX BATSAFE membrane product or support any claims about its safety to roosting bats,” he told The Ferret.

“No permission has been granted to use the University logo.” He confirmed the university team had tested the TLX BATSAFE membrane in the laboratory but added: “Bat roosts are complex environments, and as a textile scientist, I cannot comment, or take a view on how ‘bat safe’ the membrane might be following its installation in a building.” 

Row erupts over 'bat safe' roofing membrane 5
Photo by Rob Gray

A spokesperson for NatureScot said the company’s product was due to be discussed at an  upcoming steering group meeting on the use of roofing membranes. “It’s essential that any decision be based on clear evidence to avoid any risk such products may pose to bats. Our advice remains unchanged in the meantime,” they added. 

Meanwhile NatureScot claims the only safe roofing membrane to use where bats are present is bitumen 1F felt.

But TLX Insulation disputes that type 1F bitumen felt is safe for bats having conducted its own test. In a video on its website showing how the test was conducted, they conclude that the effects high temperatures have on Bitumen 1F felt are dangerous for bats as it becomes sticky enough at 80°C to 90°C, temperatures they say can be achieved in roofs in strong direct sunlight, for bitumen to be transferred onto the bats.

The NatureScot spokesperson told The Ferret: “We [NatureScot] are unaware of any evidence that bats have been contaminated by bitumen, although it is theoretically possible in the extreme lab conditions suggested in the video.  

“In practice, bats could not tolerate temperatures of anything like the 80-90°C described in the TLX video and would have already vacated the roost in search of somewhere cooler long before the temperature became that high.”

TLX Insulation was contacted several times by The Ferret and asked to comment.

Cover Photo Credit: John Martin

1 comment
  1. Out of interest, are any of the photos shown actually of the TLX Batsafe product? It seems a bit misleading to show the horrific impact of other products in an article specifically about the TLX product…

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