Plasterboard directly on rough boards?

[Mattias E Svensson]

I have a 1.5-story villa built in 1958 and have now in one room on the upper floor removed all the panel material (gypsum and some other cardboard-like panel material). Underneath is tongue-and-groove boards on both walls and ceiling, with regular insulation in the walls and sawdust in the ceiling. There was also some thin transparent plastic between the tongue-and-groove boards and the panel material, which I removed.

Now the question is whether I should put new plastic and gypsum directly on or skip the plastic? One solution is to apply plastic and then attach battens as well as OSB + gypsum, but since the room is quite small and feels even smaller due to the sloped ceiling, you lose some space by doing that. An advantage would be that you could hide the electrical wiring behind it. The tongue-and-groove boards are a bit redundant with the latter option, except that they hold the sawdust in the ceiling.

The most suitable and cheapest option is to apply plastic and put gypsum with surface-mounted electrical wiring. I don't know if I dare skip the plastic either because of the exit and 2 walls towards the attic space.

 

[GoC]

In 1958, no houses were built with plastic in the walls and roof. The house likely won't be vapor-tight anyway, so there's no point in adding plastic; it might even be worse if only parts of the house become vapor-tight. Place the drywall directly on the raw planks and use surface-mounted cables, or alternatively, rout in electrical conduits in the raw planks. But why are you tearing down existing wall panels? Feeling like extra work?

 

[Mattias E Svensson]

In 1958, no houses were built with plastic in the walls and roof. The house is unlikely to become vapor-tight anyway, so there is no point in adding plastic; rather, it would be worse if only parts of the house become vapor-tight. Attach the drywall directly to the sheathing and use surface-mounted conduit or alternatively route the electrical conduits into the sheathing.
But why are you removing the existing wall panels? Looking for extra work?

The drywall and whatever tension paper or whatever it was didn't look very nice in some places, so I want new fresh drywall up instead while we're at it. I suspect the plastic might have been added later, but it was so thin and flimsy it probably didn't function with all the nails in it, and there were a lot, I can promise you that.

 

[GoC]

Yes, then it's easier to tear out the "cheap" gypsum. I think that semi-thick paper is a kind of wind barrier. It was probably nailed onto the raw wood boards. So maybe a wind paper but no plastic. It's probably installed when the gypsum was mounted on the walls. I would guess there was tretex earlier.

 

[Mattias E Svensson]

Yes, then it's easier to tear out the "cheap" drywall. I think that semi-thick paper is some kind of wind barrier. It was probably nailed to the roof decking. So maybe a wind paper but no plastic. It was probably installed when the drywall was mounted on the walls. I would guess there was a tretex there earlier.

It was definitely a thin plastic that was there, much thinner than what is used today, and it was only in the ceiling, against the outer wall, and against the attic. There was a mix of drywall and some tension paper. There may well have been tretex earlier because I also don't think that plastic has been there since 1958.