Outdoor gypsum on the inside??

[Gustaf.P]

I'm renovating one of our spare rooms. There's a bit of a shortage of power outlets, so I've opened up and am planning to add a few extras. When I removed the drywall, I noticed that the walls have different thicknesses. Standard drywall on the wallpapered feature wall and significantly thinner on the white wall. What kind of drywall is this?? The only thing I can find online that's close is outdoor drywall at 9.5mm. But surely you wouldn't put that inside a house?? Townhouse built in 1980. What do you think?

 

[Bernieberg]

The thin board does not have standard thickness, but I have seen in previous threads that various thicknesses occur.

One solution could be to put a board around 4 mm and then 6 mm renovation plasterboard to get the right thickness.

 

[tergo]

In 1980 there was 9 mm gypsum for indoor use, I have it in my house built in 80-81. The outdoor gypsum is greenish and should not be used indoors. Having 9 mm on a wall may indicate that there could possibly be raw board behind it.

 

[Gustaf.P]

I think I'll solve this with 3mm masonite board and renovation gypsum. It's the easiest. I can't handle redoing the entire wall with gypsum.