I have laid down some 6 mm fibre cement in a bathroom in preparation for some tiling. The room was out of square and has resulted in some tight fitting fibre cement sheets both against the wall and against other sheets laid down. I know you should have a gap between floor boards and walls with wood, does the same apply for fibre cement? If it does, what would be the best way to trim it given that most of it has now been nailed down?

G'day tiger, you should leave a space to allow for movement in the surroundings more so than in the sheets. use a diamond blade in a grinder to trim it in situ
Out of curiosity, did you also glue it down with stud adhesive?

Cheers
Michael

Hi Michael,

Thanks for the quick reply. Did not glue it down, is that necessary? By the way, how much gap would you need at the wall, and how much gap between sheets if any?

5mm will do it. you only need to leave an expansion gap in the sheets if the length of the room across the short dimension of the sheets exceeds 4200 or exceeds 8400 along the long dimension of the sheet. If the substrate is particle board or ply, it should be glued too.

Cheers
Michael