Correctly Joining Cement Backerboard (Durock) In Hearth?

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New Member
Sep 15, 2017
Pacific Northwest
I've got to join two durock panels when assembling my hearth. Durock instructions note that you should join panels together and

Fill joints with latex-fortified mortar or Type 1 organic adhesive and immediately embed alkali-resistant, fiberglass mesh joint tape.
Is this the best method for a hearth? Is fiberclass mesh tape ok in this application? Should panels be butted up next to each other, or do they still need an expansion gap?


Staff member
Nov 18, 2005
South Puget Sound, WA
Fiberglass mesh is fine. The hearth will not get too hot. The panels can be loosely butted up against each other.