Hi there, I am in the process of building a Bay window seat. My issue is that the bay window walls have a damp proof membrane (the permaseal kind) and I'm unsure what my best course of action is here. Ideally the frames for the seat need to be mounted to the wall as the floor is concrete and uneven, but am I okay to drill through the membrane to attach it? Struggling to find a conclusive answer online surprisingly so any help would be appreciated! Thank you

