1/8" backerboard gap? Really?

Discussion in 'Shower & bathtub Forum & Blog' started by Snooze Reader, Mar 6, 2005.

  1. Snooze Reader

    Snooze Reader New Member

    Messages:
    1
    I installed two 3x5 sheets of backerboard in my tub alcove today. As I read from this forum I should leave a 1/8" gap between the two sheets and fill with thinset and mesh tape.

    Now that I have installed this, I keep looking at that gap and fearing that I am inviting problems for a leak. Wouldn't it be better to leave NO gap as that would protect better against water leak?

    I've attached a picture. Can someone reassure my fears?

    Snooze (Seattle)

    Attached Files:

  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I don't know if 1/8" is necessary. Check on www.johnbridge.com to see what they recommend. But ANY gap would leak if not prepared properly. This is where the mesh tape and waterproof joint compound come into play.
  3. GregO

    GregO New Member

    Messages:
    73
    Location:
    Virginia
    Snooze,

    An 1/8" gap is perfectly normal to allow for any movement without migrating through to the tiles. Thinsets are supposedly much more flexible to compensate for such movement. Therefore, you should tape and thinset every gap. I don't see any tar paper or plastic moisture barrier behind your cbu, do I??? CBU is not waterproof, but is water and rot resistant and doesn't degrade like gypsum drywall.

    Greg
Similar Threads: backerboard Really
Forum Title Date
Shower & bathtub Forum & Blog FIBEROCK Tile Backerboard vs HardieBacker Cement Board Mar 15, 2013
Shower & bathtub Forum & Blog tiling gap between backerboard and tub Jan 19, 2011
Shower & bathtub Forum & Blog Shower tub tiling flange and bowing backerboard Jun 18, 2007
Shower & bathtub Forum & Blog Backerboard bath walls May 23, 2007
Shower & bathtub Forum & Blog Backerboard questions for cultured marble shower Dec 7, 2005

Share This Page