two questions about ceilings (new/extension)

[cecar33]

If moisture can come from the sides, it can also leave that way. The important thing is that no moisture is added by coming through the waterproofing, and this is not considered to happen with modern waterproofing.

With that theory, there should never be moisture problems anywhere in a house.

 

[injonil]

Certain amounts of moisture are required for it to cause damage; what we're talking about is moisture in the warm part of the wall.

It's likely that people more knowledgeable than both you and I have concluded that vapor barriers and modern waterproofing work together and wrote the regulations. For certain things, I'm satisfied with knowing how the rules work and accept that I don't know all the reasons for how the rules have come about.

 

[cecar33]

One thing I am completely convinced of is that there are always people who have more knowledge than I do. This applies in all conceivable areas.

It is also beyond doubt that so-called experts can be wrong, otherwise regulations wouldn't need to change all the time.