Replies

1. 
   rez | Jan 20, 2007 10:11pm | #1

   Greetings Anthony,

   This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.

   Perhaps it will catch someone's attention that can help you with advice.

   Cheers

    

     

2. 
   plumbbill | Jan 20, 2007 11:31pm | #2

   I have only seen densheild in 5/8"

   Plywood reinforcememt depends on span.

   Since you are using tiles you are going to want to water proof the subsurface.

   Kerdi system is very popular.

   Red gaurd available at HD is what the tile guys on my 42story condo building are using.

   “How many observe Christ’s birthday! How few, his precepts! O! ‘tis easier to keep Holidays than Commandments.” —Benjamin Franklin

3. 
   JDRHI | Jan 20, 2007 11:47pm | #3

   Short answer....yes. You ought to have some type of substrate supporting your Denshield.

   You're not a forum cop, are you?

    

    

   
   

4. 
   copperjohn | Jan 21, 2007 04:37am | #4

   you should use 1/4" plywood and then 1/2" wonderboard screwed down to 16" o/c 2x4 framing and tile first b-4 droping in the tub... good luck...

1. 
   ScottMatson | Jan 21, 2007 11:19pm | #5

   I don't think 1/4" plywood is good enough; I'd use 3/4 for the whole assembly and screw the wonderboard to the plywood and NOT the framing members, keep it isolated. Make sure to bed the wonderboard into tile thinset before screwing it down.If you use Kerdi you don't need wonderboard at all, better off without it anyway.Scott

   Edited 1/21/2007 3:20 pm by ScottMatson

1. 
   abutcher | Jan 26, 2007 10:31pm | #6

   So if I don't use wonder board or Dens Shield, can I just tile over the kerdi, on 3/4" plywood? The tub deck is almost 4x7, with a big oval hole for a 3x6 drop on tub How close does the gap need to be between the tub lip and the tiled top? I undertsand that the tub is not supposed to rest on it. Any tricks in getting the finished deck at the right height? The tub specification says it is 19.5" high from the bottom to the lip of the tub.

   Thanks everyone for your help, Anthony

1. 
   Mongo | Jan 27, 2007 05:57am | #7

   Anthony, I'd recommend 3/4" CDX over a framed base. With the framing a max of 16" oc. You need this base to be fairly rigid.Over that use cement backer board (Durock, wonderboard, hardieboard) or DenShield. Bed the CBU into combed thinset so that there will be no voides between the CBU and the playwood. Screw the CBU down according to instructions.This is a tub deck, it's not like there's going to be standing water on it for long periods of time, so I really don't think you need Kerdi over the DenShiled or CBU. You can if you want, but again...it's up to you. Tile over the CBU/Denshield.When setting the tub, the tub is normally bedded in mortar. Plan the height of the finished tub deck accordingly. What you'll do is place the mortar under the footprint of the tub, then place the tub on the mortar, and stand in the tub to embed it in the mortar so that the rim then just touches the top of the tub deck. You can then caulk the joint between the rim and the tub deck.Sometimes the bottom of the tub can be deformed, so plan accordingly. for example, if your rim-to-deck distance is 19.5", you might want to build it so your granite tile is 20-1/2" above the subfloor. That way in a perfect world you'll have an even 1" of mortar under the tub, but with a twisted tub base, it may vary from 3/4" to 1" of mortar, with the rim of the tub being level with the deck.Hope that makes sense.Mongo

1. 
   RedfordHenry | Jan 27, 2007 07:54am | #8

   Your approach makes perfect sense.  I'd only add that it would be a good idea to have the tile, backer board and tub onsite before framing if possible.  That way he could be sure his final frame height matches the actual thickness of things.

2. 
   ScottMatson | Jan 27, 2007 05:38pm | #10

   what the others said too about the height, etc. I really like the idea of having everything on site since the height is so important.Just so you know, kerdi is actually designed to be applied over drywall! That should give you an idea about how tough and waterproof it is. I have found it to be pretty labor intensive but on something like a steam shower where you really need insurance on it being sealed completely, it makes sense.And other people love it for ease of installation compared to messy and difficult cement board, but i've got all kinds of tools for dealing with cement board. Just depends on the situation. One other thing--on fiberglass shower bases and tubs you can get by without an actual mortar bed by using cans of spray foam adhesive. I can't remember using it on cast iron but don't see why it wouldn't work well with that too.

1. 
   abutcher | Jan 28, 2007 04:04pm | #11

   Thanks everyone for the advice and the pictures. That is one heavy duty tub deck, very nice.  I was thinking just plywood on the framing like others have suggessted, but putting pluwood on sumething like that really would support the deck well.

   The tub is an American Standard acrylic tub, I haven't confirmed if the height is exactly 19.5" like it is supposed to be,  but raising the deck 1/2" to 1" and setting it on a bed of mortar or foam makes sense. The tub has two strips of wood, embedded in the fiberglass, like 1/2's spaced about a foot apart that run the length of the tub that it rests on. Is there a certain type of foam that works best?, that is most supportive but won't warp or raise the tub or if I go with mortar, any reccomendation on what type??

   Again, thanks for help!

2. 
   stevent1 | Jan 28, 2007 06:44pm | #12

   Anthony,If you use the foam, fill the tub with water first. I am using Kerdie and ditra. Here is a link for a tub deckhttp://forums.taunton.com/tp-breaktime/messages?msg=79773.136 Chuck Slive, work, build, ...better with wood

5. 
   Mongo | Jan 27, 2007 05:20pm | #9

   Anthony,

   Not the greatest pics, but one shows an old mortar bed that was under a tub that I pulled out. It'll at least give you a visual of what I'm referring to. You can see the imprint of the tubs flange in the cured mortar.

   The other shows a framed deck, in this shot it's roughly fit into the opening. Verticals "legs" were later added under it for vertical support.

   Mongo

   
   

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   Edited 1/27/2007 9:21 am ET by Mongo