Is "optional mortar bed" necessary?

Discussion in 'Shower & bathtub Forum & Blog' started by MaryAnnKacz, Feb 15, 2006.

  1. MaryAnnKacz

    MaryAnnKacz New Member

    Messages:
    18
    Will be installing Sterling Aclaim tub shower unit ourselves, or at least we will give it an attempt. From directions, it does not seem too difficult. House is on slab. I know not everyone does the mortar bed. When some say they use foam instead, what kind of foam are they talking about? Also, will we regret it if we don't use mortar or anything under tub? I know I will miss my cast iron, but I hate caulk!
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,006
    Location:
    New England
    Mortar under the tub will make it feel much more substantial and lengthen its life. The synthetic material in the tub will flex while you are standing in it...eventually that flex will cause crazing of the finish and microfractures. May take a number of years, but each time you step in, you will feel it flexing just a little. It just feels better.

    If you decide to use foam instead, be very careful - as it expands, it can lift the tub awhile after you leave, messing up the level. Also, the goal is to make the tub feel more substantial - the foam will make it stiffer, but not in the same manner as the mortar. Also, it will glue the floor and tub together - it you ever want to remove it, it is a pain (you can put a layer of plastic sheeting betwen the foam and the bottom that will allow you to remove it.
  3. MaryAnnKacz

    MaryAnnKacz New Member

    Messages:
    18
    I guess we will go with mortar bed. Boyfriend is a big guy. Exactly what do what use? Do we mix it with water? Don't know much about mortar, except thinset for tiling. Do we heap it in piles, or spread it? How thick should it be in inches? Also, can we lay plastic over this to make removal easier if we replace tub again? So I guess with a Sterling Vikrell tub, it does not rest on the floor? How much weight can these tubs hold? Does the mortar need to be under the entire tub 30" x 60", or just the the middle part of the tub the whole 5 feet? After doing this, we check for level, right? What type of shims do we use if needed?
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,635
    Location:
    Cave Creek, Arizona
    mortar

    It depends on the shower unit. Some have ribs that set directly on the floor and those do not need any additional support. Others have the floor of the unit an inch above the slab and these have to have a filler under them.
  5. sulconst2

    sulconst2 New Member

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    205
    Location:
    old bridge nj
    i use structolite from hd. its a lightweight plaster setting compound. mix with water. keep it think so not to slump too much. make 2" - 3" high mounds about 1 foot apart around the entire base. set it down and level as you set. know your high side so you don't go too low on the low side. put roofing nails above the flange to keep from raising. install cement board to the floor butted to the shower to "lock it in". good luck! ;)
  6. jammin

    jammin New Member

    Messages:
    11
    Mortar Bed

    Do you use concrete mortar or can you use plaster of paris? I have heard both before! What would be better? Thanks, Bob
  7. jammin

    jammin New Member

    Messages:
    11
    Mortar Bed

    Is Structolite the same as Plaster of paris?

    I have seen the following - what is correct or best?

    Gypcrete
    Structolite
    Quickcreke sand mix
    Plaster of Paris
    Mortar mix
  8. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Structolite was recomended.
  9. jammin

    jammin New Member

    Messages:
    11
    Structolite on Sterling tub

    I am installing a Sterling Vikrell unit. Does this make a difference on what material to use? Is there any of the above that are not desired? I have not located Structolite locally yet, so I had purchased sand mix - is that a problem? Does the Structolite break down over time from the weight on the tub bottom? I will still look for Structolite tho -thanks Bob
  10. jammin

    jammin New Member

    Messages:
    11
    Help

    I have only found sand mix and plaster of paris. Would either of these work if I can't locate the Structolite? What's best. What is the best way of laying the bed? My understanding is a 2-3" thick over entire bottom area, laying visqueen over the mud, then setting in the tub and anchoring. Any other details? Look a my other questions in previous posts of this thread.
  11. sulconst2

    sulconst2 New Member

    Messages:
    205
    Location:
    old bridge nj
    either will work or use thinset. then refer to post 5 in this thread.
  12. jammin

    jammin New Member

    Messages:
    11
    Structo-lite

    I am still trying to locate Structo-lite, and I may have a lead. What are the advantages of Structo-lite over sand mix. Pros or cons of each?
  13. sulconst2

    sulconst2 New Member

    Messages:
    205
    Location:
    old bridge nj
    the orange box sells it. its a lightweight setting compound. use whatever you got just mix it thick.
  14. finishing cement

    jsut go get some common TOPPING CEMENT

    one or two bags is more than enough.......

    this isnt brain surgery here.....


    you want to make it sort of soupy

    so when you put in the tub the cement will give

    as you sort of wiggle the unit down into it...

    you also want to pack some in from both sides too while
    you are at it.... with your hands..

    some might sort of slurp or come out the front but its ok

    jsut wipe it up


    but if you are unsure about what to mix with the cement,
    it gives me little confidence on how well this project is going to
    turn out....
    Last edited: Mar 7, 2006
  15. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    Avoid Plaster of Paris

    Avoid Plaster of Paris. It sets up too fast and you will have a rock pile before you get the tub set.
  16. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,349
    Location:
    Yakima WA
    When I set my 32" x 32" basement shower stall, I had a sack of Armstrong leveling compound that I had no use for, so I used that. It mixes up very soupy and runny, so I did have some oozing out to deal with, but a few narrow strips of an old towel make a temporary caulk that kept most of the ooze contained, and after the stuff set up, the ooze was easy to chip off. Using this stuff allowed me to set the stall in place, level it perfectly, and attach the drain before I poured. As I was working alone, I had visions of having mortar setting up before I could get the stall in place and leveled, so this seemed to be a good use for material otherwise going to waste. I really worked well! That stall is solid as a rock. The bag of stuff was fairly large, but I don't remember the weight. I think it was quite inexpensive as well. I used a mixer auger on my 3/8" drill driver to mix the goop in a 5 gallon bucket. I think it took a couple of batches. A larger stall would require more that a single bag, but it's cheap and easy to use.
  17. John Bridge

    John Bridge Mudmeister

    Messages:
    49
    Location:
    Houston, Texas
    Paraphrasing Mark Twain, much darkness has been shed on this subject. :)

    Brick mortar mix is easy for everyone to find. It's cheap and easy to use. Make it as if you are setting bricks only just a bit stiffer. It has to hold it's shape, but it has to give so you can lower the unit into it. Brick mortar contains sand, cement and lime. Home Depot sells "Mason's Mix" in 80 lb. sacks to which you just add water. There are many other brand names.

    Make mounds that will reach up higher than the floor of the unit. Space them strategically so that you'll have good support when they smoosh down a bit.

    Set the unit in and push it down to the desired height, keeping it level toward the end of the push. Then secure it so it stays in place while the mortar sets up. Stay out of it until the mud is hard -- overnight. :)
  18. sulconst2

    sulconst2 New Member

    Messages:
    205
    Location:
    old bridge nj
    this thread should be trimmed, condensed and made into a "sticky" so not to rehash the same subject over and over and ...
    but then again, "is a mortar bed necessary?" ;)
  19. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,635
    Location:
    Cave Creek, Arizona
    necessary

    "Is a mortar bed necessary?" If the shower base is a Lasco, then yes because they apparently do not know how to make the floor of the stall even with the bottom of the threshold. Most other brands have a flush bottom and a mortar base would not "compress" enough to allow the base to set on the floor.
  20. jammin

    jammin New Member

    Messages:
    11
    tub/shower brand

    I am using a Sterling Acclaim unit with webbed bottom. The floor is pretty level. Is setting in mortar not recommended? Will it help to set in mortar?
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