roof membranes and bats....

[oxonvale]

Hello all,

We are having our third and final emergence survey next week. In the 2nd survey one Common Pipistrelle was observed emerging...... Hopefully we will now get our LBC for re-roofing approved. However... the ecology consultancy are asking what membrane we planning to use. They are saying that " it would be expected that a traditional type 1F bitumastic felt with hessian matrix will be used as a roof membrane. There is an alternative bat safe modern breathable membrane available called TLX Batsafe Breathable Membrane". Clearly the bitumastic felt is not compatible with an historic roof because of the poor vapour permeability. We were planning to use Dupont Tyvek Supro breather membrane.

Does anybody have strong opinions/experience of TLX, or experience of what happens when bats are confirmed in a re-roofing scenario?

 

[malcolm]

If you look up the TLX stuff on the internet it sounds like it's something to do with 'snagging'. Presumably that's the bats getting their feet stuck in roofing membranes. Whether that is a real or imagined problem they seem to have gained local authority approval in regard to snagging bats. If that or bitumen felt are the alternatives I would go with the breathable one.

 

[Jahouli]

Hi oxenvale

Had my roof rebuilt a couple of years ago due to failing purlins, and had to get a bat licence due to brown long eared bats. I wanted a breathable membrane but had to settle for 1F bitumastic felt, which was stipulated by the ecologist and so covered by the licence. Our roofer/builder used fascia vents around the perimeter to maintain eaves ventilation. I supplemented this with lap vents I left from the old roof, and the space seems adequately ventilated. The TLX was undergoing certification at the time to prove its bat safe credentials so wasn't available.

My surveys didn't pick up conclusive evidence of emergence, and none were found present in the roof during ecologist visits, however the ecologist had to present the first morning of the roof stripping as part of the licence. Three bats were found by the ecologist before the works started, and were simply removed and released in nearby woodland.

 

[oxonvale]

Hi oxenvale

Had my roof rebuilt a couple of years ago due to failing purlins, and had to get a bat licence due to brown long eared bats. I wanted a breathable membrane but had to settle for 1F bitumastic felt, which was stipulated by the ecologist and so covered by the licence. Our roofer/builder used fascia vents around the perimeter to maintain eaves ventilation. I supplemented this with lap vents I left from the old roof, and the space seems adequately ventilated. The TLX was undergoing certification at the time to prove its bat safe credentials so wasn't available.

My surveys didn't pick up conclusive evidence of emergence, and none were found present in the roof during ecologist visits, however the ecologist had to present the first morning of the roof stripping as part of the licence. Three bats were found by the ecologist before the works started, and were simply removed and released in nearby woodland.

Did they stipulate when the works could be undertaken? E.g. was it a condition that the works had to be undertaken from late September?

 

[Jahouli]

The licence stipulated disturbance works must only be carried out in conditions when the bats are likely to be active (so usually late spring to early/mid Autumn). I suppose the idea being the bats have the energy to simply fly off and find another roost. We were racing to get our works done before that window closed, and ended up having the works done over September. The ecologist wouldn't permit the works to happen much later and we would have had to wait until April/May the following year.

 

[LadyArowana]

We had to have 2 ‘bat slates’ basically a little lead pocket in the actual slates, as well as two ‘bat boxes’. We don’t have any bats and unlikely to get any, but the ecologist had to tick lots of boxes. One of the bat boxes which we had to have in a very strange place “fell off” and went to Feltwell’s house