Shower questions

[DFWDug]

Many thanks for advice given on my guest bath remodel 2 years ago... it turned out great.

My recent project is a remodel of the upstairs master shower. I removed a layer of green sheetrock covered with 1/2" CBU. The shower liner was not presloped and the pan mortar was very wet when the tile was removed. We are moving and I'm trying to avoid completely removing the pan and opening the subfloor to replace the drain. I was able to remove the curb and lath so there is a gap to replace the lath and mud a new curb (I'm only using 1/2" CBU so the old curb was too wide).

Questions:

1. The green sheetrock and 1/2" CBU will be replaced with only 1/2" CBU (see photos) with felt backing. I have removed the mortar ridge around the pan perimeter since the tile will sit 1/2" closer to the wall. Can I use mortar to smooth out the pan surface and the space along the wall behind the old mortar ridge?

2. Can I coat the pan with Redgard and partially up the pan liner to prevent moisture from getting beneath the floor tile (since liner was not presloped)?

4. If so, should I leave a gap between the CBU and the redgard pan (I will add another row of felt that overlaps the pan liner before CBU)?

3. If I can redgard the pan, should I drill a few weep holes around the top of the drain to allow any water between the tile and redgard to escape?





Thanks again for your past and present advice,

Doug

[Davy]

Hi Doug, the gap at the wall can be filled with thinset if it's only 1/2 inch wide.

I wouldn't mess with adding Redgard to the mud bed. All you are doing is creating a mold magnet because water will get behind it. The best way to get rid of the standing water under the pan was to take up the mud bed and replace the pan liner with a preslope under it.

I would find three shower pan corners and glue them where the jamb meets the curb and also one on the corner of the curb where I see raw wood.

[DFWDug]

Thanks Davy,

I have the liner corners on my shopping list. Should the CBU be in contact with the mortar bed or leave a 1/4" gap for wicking?

I am going to insist that the shower pan be presloped in the new home. I have yet to see one done right walking through some expensive home construction.

[DFWDug]

Should the CBU be in contact with the mortar bed or leave a 1/4" gap for wicking?

[Davy]

The thing to do is to slide the CBU down in the crack around the edges instead of filling it in. That would help hold the CBU at the bottom since you can't drive nails down that low. The CBU doesn't havta go all the way to the bottom just a 1/2 inch or so to hold it in place.

[DFWDug]

I think that all CBU joints are to be taped and mortared but can you confirm that the corners are included? I couldn't remember if you left the walls independent of each other for movement (I plan to caulk all wall and floor transitions).

Thanks

[Mike2]

Tape the corners too.

Here's a link to the installation guide. http://www.jameshardie.com/backerboa...stallation.php You might want to take a few minutes and review that just to make sure you don't mess up in some other area of installation.

[DFWDug]

Thanks Mike. I remembered taping all seams last time but thought I would double check with the pros to be sure.

[Mike2]

Rather that tape all those seams before hand, it's a lot easier if you do that little chore as the tile is laid.