So, embarking upon a new studio build. We have to soundproof a ceiling and I've considered putting in a heavy membrane sandwiched between layers of rockwool. We're concerned with keeping both our noise in and potential neighbours noise out. A lot of the proper membranes seem very expensive though and our live room is 30x16 ft all in so that would cost a fortune. Are there any DIY alternatives that people can suggest? I've noticed that roofing felt seems to be mooted in some places but I've also been told that would be dangerous due to fumes that would be given off.