Leveling Shower Pan

Discussion in 'Shower & Bathtub Forum & Blog' started by jdieter, Jun 3, 2014.

  1. jdieter

    jdieter New Member

    Dec 22, 2008
    I'm installing a neo-angle shower kit over a plywood sub-floor. The instructions state to use mortar or plaster to level the base. Is the correct way to lay the mortar bed directly on the plywood or use a non-permeable membrane like tar paper or 6 mil plastic on top of the plywood first? No where in the instructions does it mention to fasten the base to the framing, which I'm assuming is because of the potential of cracking the base if it flexes. So all the rigidity of the base is relying on the mortar leveling bed, that's why I'm not sure about compromising any bond between the mortar and plywood, but also not sure about laying a mortar directly on the plywood and having it absorb the moisture.

    Also on one of the long sides of the shower base I'll have to shim it 1/2" to get level, the other long side is level as is. So on the front of the base I'll have a tapered gap with the sub-floor from 1/2" to 0". The finish flooring is 1/8" thick, so how is the gap along the front of the shower base closed, by feathering in floor level compound or is there a better way?
  2. johnfrwhipple

    johnfrwhipple BATHROOM DESIGN & BUILD for both Canada & the US

    Jul 20, 2009
    Design Work World Wide: Bathrooms Vancouver Area
    North Vancouver, BC
    Maybe you can tile the face of the ready made shower kit.

    Are you tiling the walls of the shower?

    Any mortar you want to stand alone and be strong should be around 1 1/4" thick with reinforcing. For your install I think you are just trying to get the base on a level surface. After the past year and a bit I'm loving the Ardex 8+9 undercoat and then mortar mix. This will infill the tiny gaps in the shower pan.

    I would give the bottom of the shower pan two coats of ardex 8+9 and then set the pan like one giant tile over the drain location. If you want to work on it quickly you could buy a bag of Ardex X32 as the mortar to set the base.

    If you just wanted to level the area you could use some seal gasket or edge strip kit strips to make a perimeter and then go the self levelling route. That would be my least favourite option.

    8+9 cost about $85 X32 about $55.00
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Generally, you want something on the plywood to prevent it from sucking the moisture out of whatever you use to level the pan before it can cure (assuming it is a cement based product). What you use depends somewhat on how far out of whack the floor is, and the construction of the base of the shower pan. Some are smooth, some have a grid design, some are relatively hollow. Got a link to the pan in question or take a picture of the bottom and let us know how much out the floor is.

    Bedding the pan serves two purposes...provides support so it doesn't flex and have premature failure, and allows you to level the pan for proper drainage. Once the tile is on the walls, and things are enclosed, the pan isn't really going to go anywhere especially if it has a grid on the bottom and that is embedded in something.
  5. dw85745

    dw85745 Member

    Oct 14, 2004
    Tucson, Arizona
    I just did a 38 NEO over plywood. This is what I did:

    1) Dry leveled the pan and put wood shims where required.
    Mine was a fiberglass pan,
    2) Glued the shims to the plywood cutting off any shim that protruded past the pan edge.
    3) Marked the plywood where the pan would install
    (Marked all outside edges as well as all internal X-ribbing)
    4) Layed down some thin mil (.5) clear sheet plastic so I could see my markings.
    5) Put down mortar in small mounds (about 2 inches high) on top of the plastic in each area between the X-ribbing making
    sure I did NOT get any mortar on my ribbing lines.
    6) Ran a silicon bead of caulk on top of the plastic where each X-ribbing line exists as well as on the outside pan edge markings.
    7) Set the pan and pushed down checking level after install
  6. jdieter

    jdieter New Member

    Dec 22, 2008
    I'm taking something from all the replies so thanks to everyone, and yes it's a fiberglass pan and the underside is completely covered with 4" rings about 1/2" tall to lock into the mortar. I leveled the pan with long shims, around 12" tapering to nothing same kind you get a a real lumber yard. Had 5 shims spaced around the front of the pan all pointing to the drain. After pulling up the pan I marked the shim locations and hot glued them in their respective spots. I coated the area with floor leveling primer and after it dried applied about 20 lbs of of floor leveling compound using the shims to gauge my screed board to hold the proper depth. After the floor leveling compound dried I popped out the shims and filled in the voids with a little more leveling compound. The pan now sets level with no tapered gap along the front edge. After a few days to let the leveling compound completely cure, I'll use mortar on top of the floor leveling compound to bed the shower, which will eliminate the issue of plywood drawing the moisture out.
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