Which screw for wet room board (fiber cement)

[dang]

I will screw up Ivarit Hydropanel (fiber cement) on wooden studs in the bathroom. I was recommended stainless wood screws 4 x 35 mm at Hornbach, which I bought. The same dimension is stated in the installation instructions, but it mentions galvanized screws from the same supplier as the panels.

The problem is that the screws I bought break when I use them. When there are one to two millimeters left to screw in, the screw head twists off because the board is so hard, I assume.

So my question is whether (some) stainless screws are weaker than (some) galvanized?

What screws should I buy?

/Daniel

 

[anaitis]

Have you pre-drilled?
If so - with what dimension?

 

[dang]

Nope, not drilled. Not mentioned in the installation description. Do you need it?

Link to installation description:
http://www.ivarssonsverige.se/Produkter/Byggskivor/Hydropanel.aspx?ShowIpaper=237

 

[anaitis]

You might want to think about it if the skruvarna don't hold!

 

[verktygsgurun]

Stainless screws are all too soft. Why stainless really ?? Stainless screws are possibly used for decks when screwing decking boards. Regular chipboard screws work fine for minerit VT boards anyway.

 

[dang]

So you could say that stainless steel screws are generally softer? If I now go and exchange or buy new ones, does anything work except stainless steel?

I would prefer to avoid pre-drilling, it feels like an unnecessary step.

 

[sandhall]

Used particle board screws for my Masterboard. Worked well.

 

[MaZtoR]

Stainless is soft and boring to work with.

 

[bsba]

You apply a moisture barrier on the outside so they never come into contact with moisture, so why stainless?