Mud Set Shower pan

Discussion in 'Shower & Bathtub Forum & Blog' started by Carlosa, Mar 5, 2014.

  1. Carlosa

    Carlosa New Member

    Messages:
    14
    Location:
    Texas
    Im converting tub to walk in shower, bought quickrete sand/topping , was told to pour 1/2 inch , pan liner and then another 1 1/2 with 1/4 slope to drain. Will concrete stick to existing concrete floor?
  2. Reach4

    Reach4 Well-Known Member

    Messages:
    2,402
    Location:
    IL
    Yes, it is visible.

    I don't know the answers... Regarding the pan "adhering" to the concrete, I think gravity is on your side. Concrete is strong in compression. I don't know about building showers. Maybe the question would be more understandable to somebody who does.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,134
    Location:
    New England
    What you want to make over a concrete slab is what is called a bonded mudbed. To bond the deckmud to the slab, you can either mix up a slurry of Portland cement and spread it over the slab then cover with the deckmud before it starts to dry out, or use some thinset to help bond it.

    But, that first layer, called the preslope, MUST be sloped at 1/4" per foot to the drain. Then the liner goes on, then the setting bed. The setting bed is sloped because it is already sloped underneath. Suggest you check out www.johnbridge.com for tiling issues.
  4. Carlosa

    Carlosa New Member

    Messages:
    14
    Location:
    Texas
    Ok think will do thinset since already have some from tiling floor. Other question is; shower is going to be 30' wide by 6" long, drain is 1" from wall and 5" from back wall , how much mortar do I need to line on perimeter to get the 1/4 slope? Is 1/2' ok ?
  5. Carlosa

    Carlosa New Member

    Messages:
    14
    Location:
    Texas
    Is 1/2 inch perimeter for preslope and 1 1/2' for setting ok on mortar?
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,134
    Location:
    New England
    There's a deckmud calculator at www.johnbridge.com, where they specialize in this sort of stuff, rather than a generalist site like this.

    What you've described is not ideal. You normally want the drain in the middle of the floor (unless you are doing a linear drain, where it can be at any edge, or in the middle, or actually nearly anywhere in between). The reason for this is you need 1/4" per foot from the FURTHEST point from the drain, and if it is near an edge, that slope from the 'short' side will be MUCH steeper. So, say the drain is 4' from the furthest corner, that means it must slope down 1" (4' x 0.25"). THen, if it is only 6" from the edge, it has to rise that same 1" in only 6", a very steep slope. The alternative is to keep that slope at 1/4" per foot, but then, the bottom edge of the wall will vary all around the shower pan - most people like it to be level around the bottom of the walls, and it's a lot easier than dealing with a taper all of the edges with no two tiles the same. The preslope can taper to nearly zero thickness over a slab, but normally would need to be thicker over a subfloor. The setting bed needs to be closer to 1.5" thick for best strength (it's not bonded to anything), but 1.25" over a slab can work, but more is preferred.
  7. Carlosa

    Carlosa New Member

    Messages:
    14
    Location:
    Texas
    ok, I checked the calculator but its only for centered drain, so would you say the best way to do it in order to keep it level all around is to start from drain on preslope and then do the finish 1.5? Also is the quickrete sand mix ok for both or do I need to think it with more sand?
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,134
    Location:
    New England
    I think the calculator will probably give you about the right amounts with it not centered if you keep the perimeter level. The deckmud is easier to work with if it is 'leaner' than the mix out of the bag. But, anything from around a 4-5:1 ratio of sand/cement (by volume, not weight) works pretty well. When mixing it, you want it wet enough so if you grab a handful and squeeze (think snowball), it will hold together, but not drip water out.

    The people at www.johnbridge.com do this every day, and your questions will get more coverage and responses...stay here for plumbing issues related to the shower build if you need that.
  9. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,406
    Location:
    North Vancouver, BC
    Mud Set Shower Pan Calculator

    40 pounds of mortar will cover about 14.5 square feet at a 1/4" thick.

    To work out the amount needed you do some math.

    Lets say your shower is 30 square feet. Lets say you want a 3/4" thick at the far side and 1/4" thick at the drain.

    You add 3/4" to 1/4" and divide by 2. That is a 1/2"

    Since 40 pounds does 1/4" at 14.5 square feet 4 bags will be needed to make the half inch number.

    Not so hard if you where awake in math class.

    Make sure you check when the products where made!!! Fresh product only.

    I like Mapecum Pre-Mix Fast Setting Screed Mortar for this step.
    Last edited: Mar 13, 2014
  10. dhagin

    dhagin builder:anti-builder

    Messages:
    108
    Location:
    oahu
    Double check those dimensions in your 4th post. If the drain is really 1" from a wall, it needs to be moved or you're really in for a challenge. Doubt the shower dim's too. :)
  11. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,406
    Location:
    North Vancouver, BC
    Easy Shower Build this way - NO DRAIN RELOCATE

    With your drain 1" from the wall you could install an ACO linear drain over top of a standard clamping drain. The trick to save money is to order a channel base larger than needed so you can trim the sides.

    Lets say you order the 55.12" (1400mm) drain and then cut one end off so the channel drain fits over existing clamping drain the other side would be trimmed to fit into the shower's width. Later when tiling you bring the wall tile and curb tile down into the channel to complete the sides. Then you order a 27.55" grate so that it fits inside your new shower footprint and curb.

    You can then have a nice one way slope and everything will look like a million bucks.

    Pricing for the ACO Flag drain and more info on this style of install can be found here.

    [​IMG]

    This is a rough sketch to illustrate the concept.

    You can not do this (cut the sides) of a primary shower drain. For example the drains from Noble Company, Laticrete, Quick Drain USA and Schluter all are primary shower drains so clipping the ends is a no go. Also the flanged linear drain from ACO is also a primary drain. To pull of the look and solution I showed you you need to order the plain edge ACO channel drain and install it over a primary two pieces clamping drain.

    You would prepare your pre-slope to your clamping drain. Then install the ACO drain (with clipped ends) into a mortar bed.

    Or you could skip this step all together and just float the floor to the one drain.

    So many options available.

    If you need more help planning remember that all my ACO drain order clients get one free hour of design include with their order...
    Last edited: Apr 1, 2014
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