How big, if any, should the gaps be between cement board when using for tile backer?

[Arsinek]

I saw someone saying you should have gaps between your pieces of cement board when using it for a tile backer. Is this true? If so how big should the gaps be? Also will the gap be the same size if its a cement board to drywall seam?

 

[kevinp]

I believe all CBU should have an 1/8 gap that is filled with mortar. Some manufacturers require joints to be taped with a mesh tape.

 

[Sponsor]

 

[Arsinek]

I found this on Durocks website "Fit ends and edges of panels closely but not forced together."