[MissPlace]

I'm going to replace my current fiberglass tub with a tile shower, and replace the particle board/laminate/Pergo flooring with tile. I need some help with the fine details before I finalize all my purchases and really get going with the demolition. There's pretty much one question per paragraph. I'll underline them for the sake of clarity.

My current sub-floor situation is 1/2" particle board (can be easily shredded with just a screwdriver) over 2"x6"s which are over the joists. The particle board must go, that's for certain. Can I replace it with 1/2" plywood, or would something thicker be needed? Also, is there a specific type of plywood that is better than others? Like birch vs. oak?

I am hoping to use Ditra as a substrate over the plywood. It seems like it would be the easiest for me to install, and it's thin, which is what I need if I don't want to have to modify my door. I'm clear on how to install it, modified thin-set under it and unmodified over it. However, the tile I ordered says to set it with either latex modified thin-set or epoxy. Is this a deal breaker for the Ditra? I've tried calling the manufacturer, but their phone system keeps hanging up on me. The tile is a 6"x6" glazed porcelain tile by American Olean in the Urban Tones collection.

I had a few contractors give me a bid for parts of this project with the understanding that we would be doing most of the work ourselves. Both of them said to put felt paper under the plywood, but that was when we were talking about using HardieBacker. Is this still necessary if I can use Ditra?

For the shower walls I've ordered DensShield, which is pre-waterproofed. Does anyone know if I have to seal around the screws as well as the joints when using this product? The installation brochure doesn't mention sealing around the screws, but it's kind of light on the details.

One more question. I'm installing a Tile Redi shower pan, and the installation instructions call for laying down a thin bed of mortar under the pan. Assuming that everything is properly supported, can I do this over Ditra? I've had a few people say yes, and a few people say no. Which is it?

Thanks in advance for any advice.

 

[joecaption]

Sounds like your setting yourself up for the perfect storm for a total disaster of a remodel.
I'll just touch on a few of the items and I'm sure some of the full time tile guys will be right behind me at some point.
2 X 6 floor joist are way under sized for floor joist. What's the spans and spacing?
A subfloor needs to be a minimum of 3/4" T & G.I only use Advantech for a subfloor.
It comes with a 50year warranty and will never delaminate like plywood.
It needs to be nailed with ring shank # 8 nails every 6" and construction adhesive on top of the joist.
No way would I use any drywall product like Densshield, you need real tile board.
It's remodeling 101 to cutoff the bottom of a door to allow air flow.

 

[MissPlace]

2 X 6 floor joist are way under sized for floor joist.

To clarify, the joists are not 2x6s. I don't know the size of the joists, because I haven't been under the house to look, but the 2x6s are laid flat ON TOP of the joists with about 1/4" in between.

No way would I use any drywall product like Densshield, you need real tile board.

DensShield is real tile board. This is directly from their product information page: "DensShield conforms to requirements of the 2009 IBC/IRC Code for tile backer in wet areas. It is the ideal ceramic tile underlayment for new construction, bathroom remodeling, pool areas, and many other high humidity or wet areas." DensShield is basically like using Kerdi, only it's already put together.

It's remodeling 101 to cutoff the bottom of a door to allow air flow.

I can't see any reason to modify the door if I can just as easily keep the floor at the same level. I assure you that the door is not hermetically sealed in its current configuration.

 

[oh'mike]

Tile Redi Shower Pan Question - Kitchen & Bath Remodeling - DIY Chatroom - DIY Home Improvement Forum

Do not attemt to use the 'Tile Ready" pan----way to many failures---

For a premade pan Check out Schluters line--or Latacrete pans---

We can give you better advice on the floor if you can tell us about the floor joists--size, spacing and unsupported length---

For the subfloor---remove the bad particle board--nail or screw the 2x6 --then top with 1/2" or thicker BC plywood (exposure one)

Jaz is the best active member that know the best methods for Ditra---perhaps he will see this thread and comment--Mike---

 

[JazMan]

Hi all,

We already know the particle board is junk and must be taken out. Use a 3/4" subfloor that is rated exposure 1.

I knew the 2 x 6 were the subfloor and not the joists. Joe just misunderstood cuz it's not a normal thing. If you had told us you lived on the left coast (am I right?), he would have caught that too. That's why we ask that ppl tell us where the heck you're located. :laughing: So, northern California, Oregon Wash State?

Ditra is a good plan. Install it exactly as you stated. Mod under, unmod to set all tiles. The porcelain tile manufacturer doesn't know you're going over Ditra. You gotta use mod for all applications except Ditra and Kerdi installs.

Felt under the subfloor may be a local thing. If you're where I think you are you probably have a crawl space that may get pretty damp. While we're talking about under the floor. Get under there and tell us what you see for framing. A few pics would be nice too.

Are your shower walls a stall shower or a tub enclosure? Makes a big difference. If a stall shower, I do not like to use DenShield cuz of the way they want you to do the bottom part. Have you studied their sketch?

You do not use Ditra inside a shower. Where did you read that? I do not use Tile Redi.

Jaz

 

[MissPlace]

I am, indeed, a left-coaster. I'm in the damp half of Oregon.

As far as the felt paper goes, it was meant to be a vapor barrier. But it is my understanding that Ditra is a vapor barrier, so if I use both my worry would be that it would trap moisture in between and create a mold playground. There doesn't appear to be any kind of vapor barrier currently installed.

There is some confusion about my plan for the shower. I have already purchased the Tile Redi base. That ship has sailed. I read the thread of people having issues with it, but I saw a lot of people there installing it incorrectly and then complaining when there were issues. I hope to not be one of those people. I also hope the problem isn't in the base itself.

I would be putting the Ditra under the pan, not in the shower itself. So, the order of the floor in the shower would go substrate, plywood, Ditra, mortar, shower pan, tile.

As far as the DensShield in the shower is concerned, the Tile Redi base will act like a really short tub. The edges of the pan will be flush with the edge of the DensShield, both are completely vertical, and they will be sealed with silicone in between as per instructions. I have studied the DensShield installation instructions, and for my purposes it will be like I'm installing it in a tub enclosure. However, I'm still unclear on if I should seal the fasteners or not.

 

[MissPlace]

I just tried to link pictures, but I'm so new it won't let me until I've posted 5 times.

Anyway, I checked under the house and my joists are really far apart, between 5' to 6'. Not counting the perimeter of the house, there are only 4 of them. In a few more posts I can send a picture if it's needed. But it's basically just 2"x6" boards laid across joists that are about 5' to 6' apart.

 

[jeffnc]

As long as the particle board is in good shape, I would leave it in place and put 3/4" standard plywood right over the top of it. 1/2" total isn't enough support. This might bring up the level of your floor, but you're going to have to do it anyway.

High quality unmodified thinset is good over Ditra, regardless of what the tile manufacturer says.

Paper under the plywood isn't necessary with Ditra and tile.

I don't understand your question about your shower pan/mortar over Ditra. Ditra would not go in your shower area. Personally, I use Kerdi and the Schluter shower kit, so I can't comment on the Tile Redi.

 

[jeffnc]

As far as the felt paper goes, it was meant to be a vapor barrier. But it is my understanding that Ditra is a vapor barrier, so if I use both my worry would be that it would trap moisture in between and create a mold playground.

That's correct. Ditra isn't exactly a good vapor barrier if the seems aren't sealed with Kerdi band (which is really easy, if that's what you want.) However I definitely wouldn't use Kerdi and tar paper together, as you said.

I would be putting the Ditra under the pan, not in the shower itself. So, the order of the floor in the shower would go substrate, plywood, Ditra, mortar, shower pan, tile.

Ditra is a waste of time under the shower pan. Ditra provides a layer between plywood and tile, because plywood is not a dimensionally stable substrate (i.e. it shrinks and expands.) Your pan isn't going to crack like tile might, so you don't need Ditra.

 

[JazMan]

That's very typical framing set up out there. It's not listed as an approved method in the TCNA Handbook, but we know of many floors covered with ceramic tiles built just like your.

Just gotta verify everything is well fastened and feels good.

Felt paper is not a vapor barrier, it's a vapor retarder. Ditra is not a vapor barrier in the true sense of what barriers do. The back of Ditra along with the interconnected channels actually allow moisture to escape and equalize. It does not keep it on the other side. However, if it's not a required thing, you shouldn't use it. Just make sure the crawl space is well ventilated, insulated and the ground has an appropriate barrier per local custom.

As for the Redi base, I think 99.9% of products work as advertised if installed and used correctly. My only contact with one was on a shower I did where one was installed before I got the job and was done wrong. The whole thing was bouncing like crazy. To the curb it went, and I did a Kerdi shower.

I guess I don't see any harm on installing Ditra on the floor under the pan. It's not necessary but...............

As long as the DenShield is not buried in the deck mud (which there isn't any here), it will be ok. If I recall the directions, it says not to apply a sealer over the fasteners unless the face is broken. It's a common thing that most ppl spot the heads and seams with liquid membrane though.

* Jeff misunderstood about the 2 x 6's too. I told you it's not common.:wink: That reminds me, once the particle board is out, you should go with 3/4" subfloor grade and not 1/2 ply.

Jaz

 

[MissPlace]

Ditra is a waste of time under the shower pan. Ditra provides a layer between plywood and tile, because plywood is not a dimensionally stable substrate (i.e. it shrinks and expands.) Your pan isn't going to crack like tile might, so you don't need Ditra.

But I need something between the plywood and mortar. The other option would be to put down some concrete backer, but as long as I'm applying Ditra over the rest of the floor, is there anything wrong with just putting it under the shower pan as well? My reasoning is that I'll already have some, it's much lighter weight so I can install it with no help, and it will be easier to cut the drain hole.

I did look up how to seal Ditra with Kerdi, and it is pretty straightforward. I don't think it would be a problem.

 

[jeffnc]

But I need something between the plywood and mortar. The other option would be to put down some concrete backer, but as long as I'm applying Ditra over the rest of the floor, is there anything wrong with just putting it under the shower pan as well?

No, but it's a waste of time. Why would you bother? Not sure why you think you need something between the mortar and plywood. Maybe it has to do with your shower pan, which I'm not familiar with. If you're talking about making a drypack mortar base on top of plywood, then I kind of see your point - if it's easier for you to put down Ditra than tarpaper, I guess it's OK. My understanding is that in that case, tarpaper simply keeps the plywood from absorbing too much moisture from the drypack mortar before it cures, and Ditra would do that too. If you're talking about thinset mortar to adhere the shower pan to the floor (as with Schluter shower pans), then you don't need anything else - it adheres directly.

 

[MissPlace]

Jeff, when I say that I need to put the base in mortar I mean a mud base, not thinset. That may have been the source of much of our confusion.
The instructions for the pan say, in bold, "Please note, do not place the mortar directly on a wood substrate," and I'm pretty sure it is to prevent the plywood from absorbing the moisture, as you said.

 

[MissPlace]

Ok, so I'm going to remove the particle board, replace it with 3/4" plywood rated exposure 1, then put modified thinset down under Ditra over the whole area. I will seal the seams with Kerdi-band using unmodified thinset (I was thinking of doing this anyway because I have destructive and water-loving offspring). I'll float the shower pan in a mud base, and install DensShield on the walls in the shower enclosure. I'll use some RedGard to go over the fasteners, because I also need to use some to cover the edges of the backer around shower niches.
For the order in which I install the tile, I was planning on starting on the walls around the shower niches, and going out from there. I will have some questions later about the best way to make the cuts around the shower head & stuff like that.

 

[JazMan]

HUH? What happened to the shower pan? Are you going in a complete different direction?

Jaz

 

[MissPlace]

I'll float the shower pan in a mud base, and install DensShield on the walls in the shower enclosure.

The shower pan is still in the plan.

 

[MissPlace]

I just thought of another question or two.

What kind of fasteners should I be using on the 3/4" plywood, and how far apart should they be?

Also, I'm not sure what to do about the baseboard. I got some matching 3"x12" bullnose tiles for the purpose. There is textured and painted drywall all the way to the floor, and I'm thinking that applying tile straight to it is a bad idea. Should I scrape off the texturing and apply the tile right to the drywall? I'm going to have RedGard anyway, so should I put it over the areas that will be receiving tile? What is normally done in this kind of situation?

Also, speaking of drywall coming down the floor, my new substrate will be higher than the old one. Do I need to cut the bottom of the drywall to fit the new plywood underneath the bottom edge, or can I just put the new plywood up to where the drywall starts and leave a little gap under the bottom of the drywall?

 

[jeffnc]

If going over 1/2" existing subfloor, use 1 1/4". If going directly over joists, use 2", driving directly into the joists.

Adhering tiles directly to the textured wall should be fine. Think ahead to how you will caulk or grout it.

As to your last question, I was with you until you said "gap under the bottom of the drywall". Do you mean your new subfloor will be 3/4" while your old one was 1/2", so now your floor is open to the crawlspace in that gap? If so, that gap should be filled with insulating foam or something to keep out bugs and drafts.

 

[MissPlace]

Jeff, my floor is not like what you're describing. I swear to you that my existing subfloor really is 2"x6"s laid 1/4" apart over joists that are spaced 5'-6' apart. There is, quite literally, only one joist that passes through my bathroom, and that is only in the narrowest section close to the door. There is no existing 1/2" subfloor, and there are no joists. Also, I thought attaching the plywood directly to the joists was a no-no in this kind of situation.



Yes, I meant that my new subfloor will be 1/4" higher and there will be a gap under the drywall. Insulating foam would not be a problem to get in there, so I'll just do that.

 

[JazMan]

I understand what you're saying about the supporting mud under the Tile Redi. :thumbsup:

You should use 2" deck screws to install the 3/4" ply subfloor over your 2 x 6 subfloor. That means the 2" screws will bite 1 1/4" into the subfloor which is probably actually 1 1/2" thick. Be sure to gap the sheets 1/8" per normal. No glue is to be used. The new ply should be gapped 1/4" all around.

I don't think you'll need/should scrape the texture for the base moldings. It'l work as is. Grouting will be the same pain either way.

Jeff has dealt with your kind of framing either.

Jaz