Putting new ceiling panels over the old ones in the bathroom, is plastic needed?

[gluecifer]

I'm going to install new ceiling panels, 6mm thin boards that I plan to nail onto the old ugly ceiling in the bathroom. There is diffusion plastic above the old ceiling, what should I do now - do I need anything between the new and the old ceiling panels?

 

[Ola78]

It shouldn't be necessary if there is already plastic. Do you know if it is intact? Otherwise, you should repair it, as bathrooms are even worse with warm humid air, so it is important to have an intact vapor barrier.

 

[gluecifer]

It shouldn't be necessary if there is already plastic. Do you know if it's intact? Otherwise, you should repair it. Bathrooms are even worse with warm humid air, so it's important to have an intact vapor barrier.

Mm...I'm not entirely sure about the condition of the plastic...I don't really want to tear down the old ceiling
Can you add plastic again now, before the new ceiling panel?

 

[calle_77]

If using double vapor barriers, isn't there a risk of moisture getting trapped between them, which then gets stuck and forms mold in the old ceiling?

 

[Ola78]

If you use double vapor barriers, isn't there a risk that moisture will get trapped between them, leading to mold formation in the old ceiling?

You should avoid using double vapor barriers, it's never good.

 

[AndersS]

What type of ceiling is it? If it's a painted plasterboard ceiling, you can apply a latex sealant around the ceiling in the seam between the wall and the ceiling to seal it.

 

[gluecifer]

It's some form of tongue and groove wood paneling, about 1 cm thick I guess. And it now looks like the plastic above is damaged here and there.

What happens if you seal the current joint between the wall and this ceiling with some form of latex/silicone, and then put new plastic directly under the old ceiling, before the new ceiling panel?

That plastic will be nailed through with the new ceiling panel..?