How to install subfloor panel in fiber cement?

[Björn Sj]

Hello
I've purchased Byggmax subfloor board in fiber cement.
Which side should be facing up? The smooth or the rough one?
What's the best way to cut it without filling my lungs with fiber cement dust?
Grateful for answers from those with experience!

 

[Erik Jansson1]

We installed fiber cement boards from Byggmax in the cabin a couple of years ago and as far as I remember, there was no right or wrong side. Check the product page to verify this.

We cut the boards with a utility knife. You score the board a number of times and then gently break it against an edge.

 

[Björn Sj]

Hello
I've bought Byggmax furring strip board in fiber cement.
Which side should be facing up? Smooth or rough?
Best way to cut without getting lungs full of fiber cement dust?
Grateful for answers from those with experience!

We installed fiber cement boards from Byggmax in the cabin a couple of years ago and as far as I remember there wasn't a right or wrong side. Read the product page to verify this.

We cut the boards with a utility knife. Score the board several times and then carefully break it over an edge.

Thank you! Byggmax is unsure...

 

[Claes Sörmland]

It's a classic question when it comes to masonite boards as well. I had an inspector who claimed that the rough side should face down on masonite boards because condensation can settle there and it doesn't form larger droplets, instead, it evaporates better or is absorbed into the masonite more easily. Perhaps the same argument can be used for fiber cement boards? On the other hand, they have such a high pH that nothing is likely to grow on them for the first 50 years.

 

[Weimik]

I recall using a regular circular saw outdoors when I cut mine last year. Didn't feel like it created notable dust in my lungs.

I also seem to remember concluding that it doesn't matter which side ends up facing down.