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01-20-2006, 10:24 AM
:wave: Hi all, my name is Annie and I've been doing lots of reading here. Redoing a bathroom in my 30-year-old house and would appreciate some advice. Here's scenario as briefly as possible: Floor area is 5'x10' which I want to tile with 12x12 porcelain tiles, doesn't include any area under shower or tub, just adjacent to tub. Removed vinyl sheet flooring, scraped subfloor clean of adhesive, top layer of subfloor is 1/2"Masonite (name stamped on floor), which is nailed to a 1/2" of plywood underneath, on 2x9(1970's version of a 2x10?) joists on 16" centers, over dry, heated finished basement area. Floor well supported by bearing walls underneath (of a laundry room, doorway, and a nearby jackpost), no span over about 5' unsupported. There are a couple small spots around toilet and one edge of tub that show watermarks from moisture getting to subfloor, but Masonite is level and sound, no deterioration. Local tile guy told me I can thin-set & screw down 1/4" Hardibacker onto the Masonite to set tile on. I'm concerned though about moisture in thin-set on that Masonite, so what are your thoughts on that? Removing subfloor is not an option - husband would leave :lol2: I tiled a 16'x16'floor in an addition on a cement slab, 15 years ago, as well as a slate tile floor on slab, both turned out great and not even a grout crack to this day, so I know I can set and grout tile successfully, but know the right underlayment is key to good job. Would most appreciate your advice! Am also planning to do 12x12 tiles on a short span of wall, on primed drywall in "non-wet" area, so any tips/advice on that are welcome and appreciated as well. Thanks in advance, Annie

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01-20-2006, 10:29 AM
Hi Annie welcome! Well then hubbys gotta go cuz so does the masonite. I would tear it out and add a layer of 5/8" ply then Ditra in your situation. But that's me. On the wall you can use thinset to stick the tiles to the drywall.

01-20-2006, 11:56 PM
Thanks for replying, Mike. Not a happy household tonight after told hubby about floor concerns, I've been doing alot of reading before broaching the subject so I had the full picture and I was afraid of the tear-out scenario, but seems like that's what will have to be done. I am familiar with use of hardi, is there a reason I shouldn't use thatwith thinset instead of Ditra? Never used Ditra, how difficult is it for a first time user? (I read the description at Schluter, looks a little intimidating. How expensive ?(already have busted the budget for this project!) Appreciate your help! Annie

Indiana Floors
01-21-2006, 12:02 AM
Did you get my message?

01-21-2006, 12:09 AM
Welcome, Annie. :)

What Mike said. You could also use CBU over the newly installed subflooring if you prefer. I just wouldn't put a tile installation over the Masonite - even half-inch Masonite, which I've never seen.

My opinion; worth price charged.

01-21-2006, 12:02 PM
Thanx, CX, and turns out that Masonite is 5/8", was hard to measure in those little holes where I could get to it. I'd sooner use the CBU just because I've used it before and know how to do it.
Indiana, thanx for the message, wanted to do a little reading on that site before I got back to you, did that last night. On the list of surfaces that will go over, particle board/Masonite doesn't appear (doesn't appear on any lists of acceptable materials for anything - can't imagine why the builder used it in our bathrooms!!) Husband is adjusting to idea of tearing out, he's still here :D I had him read a post that says it will go quicker than you think....Thanks lots for your help. Put crown molding up this morning, which was piece of cake for once! Happy weekend, Annie

01-23-2006, 06:44 PM
hello again, have a few new questions for the good people so generous with their experience/knowledge, this site is a gem! Having adjusted to the idea we have to tear out the Particle bd./masonite underlay., I started calling around to find a toe kick saw to rent. 12 calls later finally found one over 30 miles away, 50 bucks a day (expected) but didn't expect to have a 60 mile trip each day for this phase of project. Since bathrm. is only about 5 ft. wide x 10' long and masonite only has to be cut along the 10 ft wall on one side and 5 ft of opposite wall - rest of that wall is the tub and masonite ends at its outer edge, do you think we can do this with a circular saw and pry bar? Along walls, the masonite goes under the drywall 1/2" ( to the framing plate) so figured we could probably pry out along there if we cut up the main part of the floor in smaller pieces with the circular saw and just leave narrow strips along wall to pry up. Would be a messy pain, but maybe better than 60 miles a day for a saw? Any other ideas for us? Called some tile stores around here to see if anyone had a toe kick and see what it would cost to have someone do it for us, no one got back to us as yet.
Other question: when we put in the 5/8" exter. plywood for the new underlayment, should we screw that just to the 1/2"plywood underneath and not down into the joists? Did I read that here on another thread, or am I thinking of the rule not to screw the CBU to the joists? Checked out the deflecto for our situation and we are fine ther, neat tool. And, just to be sure, I can put the modified thinset right onto the new ext. plywood and then the CBU into the thinset, correct? I can't wait to get past all this and get to the tile setting - that's the part I like to do! Husband (T.K.) has been reading over my shoulder alot and is very impressed with all the info offered here and the time you guys spend helping anyone who asks! Thanks lots, Annie

Indiana Floors
01-23-2006, 07:23 PM
Good call on the removal.
It was the best choice!

01-23-2006, 07:31 PM
If you are very coordinated, you can use a sawzall. It is tough to only cut the layer you want, but it is possible. If it wasn't so thick, you might be able to score it and break it off after removing most of it. To remove most of it, you can set the depth of a circular saw so it is only going through the part you want to remove, then pry it off. My non-pro thoughts...

01-23-2006, 08:17 PM
Thanks for your suggestions, Jim - we did think of the sawzall - we have one and have used it for other destructive purposes :devil2: , but were afraid of cutting too deep as you mentioned, that's why the speculation about using the circular saw where we can set the depth. Think we are going to try that if we don't hear from any of the flooring people we left calls with today - I'm sure none of them would rent out a tool (I wouldn't ask!) and figure it might be pretty expensive to get someone here just to make what amounts to about a 17 foot cut in the floor when they could be working on more interesting jobs.... Yes, Indiana, I think this "path' is the right one, thanks for the validation. Would you like to know how it turns out? - might be worth a few laughs :D Thanks, Annie

01-23-2006, 09:11 PM
Would appreciate if someone would weigh in on the 2nd part of my last post about securing the new layer of 5/8" plywood, etc., then I think we're "good to go!" Thanks lots, Annie

01-23-2006, 09:17 PM
On the plywood, you want deck screws long enough to go through the layer below. Offset the sheets from that underneath by about 4" and lay it the same direction as what is there (i.e., across the joists). You could probably use ring-shank nails, but I'll let one of the pros confirm that - quicker than screws and less likely to have an occasional one thatsits high. By offsetting the second layer, you'll avoid the joists. An occasional one won't hurt. My unprofessional understanding from previous posts.

01-23-2006, 09:43 PM
Almost what Jim said.

You want the ends of the new layer of plywood to fall one quarter of the way into a joist bay (four inches past a joist in your case), but not a joist bay that has a joint in the first layer of plywood on either side of it if possible. That is, don't have the end of the new sheet fall four inches beyond the end of the old sheet unless there is not alternative - which there will be. :)

And have the long edge of the second layer overlap the layer below by half wherever possible.

Fastening to a half inch layer of subfloor (I just hate it when people do that :mad: ), I would pre-drill all the holes in the new plywood before fastening to prevent "screw jacking" and stripping out the screws.

My opinion; worth price charged.

01-31-2006, 08:57 PM
Thank you, Jim and Cx for those last two replies, sorry I didn't acknowledge sooner - messed up a shoulder & couldn't type, busy recuperating. The masonite is gone, replaced by a lovely layer of 23/32" BCX on top of the old 1/2" ply, ready to be screwed in place tomorrow. Want to check on two issues, if you would be so kind;
1. We cut the BCX with the proper 1/8" gap between sheets, 1/4" perimeter gaps, and were lucky that the seams could be placed almost exactly as they ideally should be. We couldn't get the new BCX under the drywall since it's a tad thicker than the old masonite, so there's actually a 1/4 perimeter gap between the bottom drywall edge and the BCX, but there's 3/8" more gap under that drywall edge back to the sill the walls rest on. Should we use sill seal in those perimeter gaps, seems like an awful lot of space in there! We decided to use Ditra on top of the BCX, after reading more about it, seems like the best way to go (Muskymike, please feel free to say I told you so :laugh2: ), but didn't want the thinset we put down under the Ditra to fill all that perimeter gap space. Also, on three of those walls, we will be installing 12x12 wall tile on the drywall to about 4 feet up on the wall, so those gaps along the wall worry me.
2. One of the perimeters is against the side of the tub. Should we caulk that 1/4" gap before putting down the Ditra, and if so, what kind of caulk?
Thanks so much for all your help - we never would have gotten all this "right" without the help we found here! :clap2: Annie

02-01-2006, 08:57 AM
I posted late last night and just wanted to make sure my last 2 questions didn't get lost far down the list, since husband is raring to go on fastening down the new BCX and putting in the sill seal (I'm out of commission for now :o ) and is already starting without me! Thanks! Annie

02-01-2006, 09:02 AM
Hi Annie, you don't have to worry about the gaps, if it makes you feel better you can put some sill seal in but it's not necessary. You can caulk the Ditra to the tub after you put it in.

02-01-2006, 02:57 PM
Thanks for your quick reply, Mike. Gee, we might actually get to set some tile soon! Will let you all know how it turns out, thanks again for all the help :) Regards, Annie

02-08-2006, 01:12 AM
Wish I was back here to tell you our tile job is all done, but unexpected turn of events has me here asking a different sort of question. Long story short, with all the prep work I ruptured a rotator cuff in my shoulder (one that was already operated on 10 yrs ago) and there's no setting tile or grouting in my near future. Husband is good spreading thinset but never did any grouting and doesn't want to "practice" on our good new porcelain tile :) (perfectly fine with me), so now we are looking to hire a pro. Pro who did work for us in past, and got our tile for this project, is tied up for months and said no hard feelings if we look for someone available. Found a local referral service that prescreens contractors for all sorts of work (all local people who have been in business here at least 5 years), and matches them to homeowner's need and have two appts. set up with two different contractors. Can you give me advice on what I need to ask to choose a good tile pro? References will be provided, which is helpful but even that isn't always reliable unless you get to see the work that was done. Haven't had a lot of experience hiring contractors for anything but some electrical work, and window replacement - both good experiences. Would like to repeat that! Any help you all could offer is greatly appreciated. And I am really disappointed - after all the preparations, I was looking forward to doing the tiling! Thanks, Annie

Indiana Floors
02-08-2006, 06:48 AM
Ask him if he has a wet saw or he rents one, for starters.
If he does not have a Target he is no pro (just kidding)

Then ask for pic of jobs he has done.
Personal job referrals etc.

I would be leary of a referral service,they are rarely in it for the consumer,it is all about the book balances.

02-08-2006, 11:56 AM
You should mention the Ditra when looking for a contractor. Unfortunately, many contractors only want to do things the way they always do them, and so they may resist it's use. I know of two contractors who absolutely refused to hang a poly vapor barrier behind CBU in a shower, and for one of them, I even delivered my leftover roll of poly to the job site.

On the other hand, many amateurs have gotten professional results with the help from this site. So if your husband is up to it, you might consider ordering John Bridge's book as a reference, and have him do the job.

Grouting is really not that difficult. You might consider using one of the newer grouts like Custom's Prism (although other manufacturers have similar products) which help avoid color variations in the grout, which is a big complaint. It also is more stain resistant than regular grout.

And here's to a speedy recovery for you!

02-08-2006, 01:22 PM
That's a good point, Jeff, especially since we already have our roll of Ditra and the thinset for installing it and we absolutely want to use it. I did mention that when I described the project to the woman who runs the referral service. While I understand the concern about such services, Indiana, this woman is a local teacher we know who started this business so she can eventually work from home to be there more for her family. She's very conscientious and enthusiastic about providing a service for consumers that she's seen a need for in her own experience and that of friends and family, so I feel pretty comfortable about this. Of course the test is the quality of the referrals....we will see. From own experience, I don't think grouting is all that difficult either, and broached the idea of doing some "test boards" with other left over tile for husband to practice on, but he sort of balked at the idea, think he's afraid he'll mess up and we've already spent alot on this project even though it's just a small bath. He's busy with alot of other things too so guess we will have to hire this one out. Thanks, Jeff, for your good wishes, hope just some rest and therapy will do it this time, will find out tomorrow when they review the MRI! (Rest is SO boring..) :yawn: Thanks again, Annie

02-17-2006, 01:26 PM
We have finally found a tilesetter with great references and a high recommendation from a friend who is very meticulous in his own business of laying wood flooring. We were very impressed with his attention to all the details when he came to look over the job we now can not finish ourselves. He has used Ditra on quite a few jobs, he said - he works full time for a long-established large local flooring company and does side work as well, but I was confused when he told me how he would install the Ditra and thought I would run it by you all here. He said he would use modified thinset on top of our BCX underlayment to imbed the Ditra, then immediately screed over the top of the Ditra with the modified thinset to fill all the little squares and get a nice level surface to set the tile. He would let that set up for a day and come back in to set the porcelain 12x12 tile with the same MODIFIED thinset , then in about 2 days time come back to grout. Everything I read here and on the Schluter site says to use UNmodified thinset to set the tile because of drying problems with the modified between the two basically impervious surfaces. Do I have that correct? And, if so, am I within bounds to tell a pro that I want him to use a different method to set our tile (albeit, tactfully!) He's calling back in a day or two(though it will, as we expected, be 4 weeks til he can put us in his schedule), please help.... Thanks, Annie

02-17-2006, 04:47 PM
Here's the Ditra Installation Handbook. ( It's the gospel according to St. Schluter. It might be useful to print and share (tactfully, as you said) with your installer.

Pre-filling the Ditra waffles has been discussed and generally approved of by this forum. Since that layer will not be covered, I would think modified would be OK. As for the setting of the tile, well, I'll leave the debate to others.

02-17-2006, 05:04 PM
Thanks, Jeff, I have the handbook, which as you suggested I intend to share with the installer after I wade through all the opinions on this issue. I've been reading the threads provided by Mike 2's links (thanks!), which is enlightening and also further confusing! Doesn't appear to be an easy consensus, but I would lean toward following Schluter's recommendations - at least I think so :uhh: Annie

02-18-2006, 12:43 AM

I too struggled with the same issues you are regarding modified vs unmodified thinset both with my Kerdi shower and the Ditra I'm using on my bath counter and floor. I don't doubt that many of the pros on here have great sucess with the Schluter products and modified thinset.

Ultimately, my concern over the warranty convinced me to follow Schluters' guidelines and use unmodified. They will not honor their warranty if the guidelines in the handbook are not followed. I don't know if that is a priority for you but I thought I would mention it.

Good luck!

02-19-2006, 08:48 PM
I was confused when our prospective tile installer told me how he would install the Ditra and thought I would run it by you all here. He said he would use modified thinset on top of our BCX underlayment to imbed the Ditra, then immediately screed over the top of the Ditra with the modified thinset to fill all the little squares and get a nice level surface to set the tile. He would let that set up for a day and come back in to set the porcelain 12x12 tile with the same MODIFIED thinset , then in about 2 days time come back to grout. Everything I read here and on the Schluter site says to use UNmodified thinset to set the tile because of drying problems with the modified between the two basically impervious surfaces. And if modified is used, it involves extended drying times before grouting -like 6 to 14 days? Do I have that correct? And, if so, am I within bounds to tell a pro that I prefer that he use a different method to set our tile (albeit, tactfully!) He's calling back in a day or two(though it will, as we expected, be 4 weeks til he can put us in his schedule), please help.... Thanks, Annie[/QUOTE]

The above post got lost among all the new ones, and I would really appreciate some of the tile pros here taking a look at the above described "methodology" and giving their informed opinions. Has been left up to us to get the thinset we want him to use, and I REALLY need some clarity on this issue - keeping me awake at night! I appreciate Ken's response - warranty is indeed important to me. By the way, is there a way to modify the title of my posts in the forum? - we are so far past "masonite subfloor" and it doesn't reflect what my current questions are at all..... Thanks, Annie

02-20-2006, 06:49 AM
AnnieKay, your tile guy's method of skim coating the Ditra before setting the tile is well recieved here on the forum. The folks at Schluter have seen it and have not outright banned it's use. I would not be uncomfortable with using modified thinset in the manner your guy proposes.