Plastic above the ceiling.

[A.J.]

Hello.

We live in a 1½-story link house built in 1976. We are going to replace the ceiling in a bedroom, from a Barracuda ceiling to plasterboard or paneling. Sometimes we've heard a clicking sound above the ceiling when we've flushed the toilet or sink in the bathroom above. We thought we’d try to investigate the cause of this. I removed a piece of the Barracuda ceiling to look into this. Then I saw that there is a black plastic above the current ceiling (see picture). The plastic runs along the entire exterior wall as far as I can see. Above the plastic, there is sparse paneling and insulation. In the middle of the house, there is no plastic or insulation.

What is this plastic for? Is it just for insulation against the outer wall, or does it have something to do with moisture protection? I have to cut away some of the plastic to see the pipes above, so I want to know if I need to replace it with new plastic afterward. Can I screw plasterboard/paneling directly onto the plastic, or do I have to nail additional sparse paneling onto the plastic first?

Regards, Andreas.

 

[A.J.]

Measured a bit and concluded that there is a cold space above the floor right where the plastic is located. The house has a sloping roof and the upper floor is a bit narrower than the lower floor.