Why don’t bats and breathable membranes mix?

Oct 1, 2025

Most of you will have heard that bat roosts require traditional type 1F bitumen felt rather than modern breathable membranes — but have you ever stopped to ask why?

The photos below tell the story better than words, but here’s the explainer:

Urine damage: bat urine quickly degrades breathable membranes, drastically shortening their lifespan.

Claw snagging: the loose fibres of breathable membranes catch on bat claws, causing the material to fray. Over time, this can entangle bats — leaving them unable to free themselves and then tragically starving.

From an ecologist’s perspective, it’s clear: when bats are present, 1F bitumen felt is the only safe choice.