Using thinset to level floor

Reply

  #1  
Old 04-20-06, 09:25 AM
Member
Thread Starter
Join Date: Apr 2006
Location: CT
Posts: 9
Received 0 Votes on 0 Posts
Using thinset to level floor

Hi everyone,
I'm just about to start laying tile in our half-bath (roughly 18 s.f.) and have a question about leveling the floor. I was laying out the tile last night to try to get the best possible pattern (i.e. to avoid a lot of cutting and hiding the cuts when necessary). In doing this I noticed the floor was a little unlevel around the toilet (approximately 12" -15" from mid toilet to back wall). I would estimate maybe an 1/8" to 1/4" off level. I looked into getting a leveling compound for the floor but all I could find were the big buckets that was way more than I needed and pricey to boot. Now my question: Can I use the thinset to skim coat the unlevel section (roughly 15" x 30"), let it dry and then begin tiling over that with thinset again? Will the second coat of thinset adhere to the skim coat? I thought about building this section up a little more as I start to lay the tiles, but I would have no way to tell how high to go to make it level with the rest of the floor. Maybe the 1/8" to 1/4" is not a big deal and can be accounted for when tiling, but I don't want to start until I can be certain. Thanks in advance and this site is a great wealth of knowledge for those newbies like myself.
Louis

p.s My layout plan will be to have full tiles at the entryway to the bath from the hardwood hallway and cut the tiles on the opposite wall (all tiles on that wall will have cuts less than half the tile, as is the preference). Going longitudinally, I plan to have full tiles behind the toilet and hiding the cut tiles under the toe-kick at the sink (again tiles will have cuts less than half the tile). How does this sound?
 
Sponsored Links
  #2  
Old 04-20-06, 12:52 PM
Bud Cline's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2001
Location: Central Nebraska
Posts: 1,300
Received 0 Votes on 0 Posts
Yes, thinset can be used for filler but it has its limits. Thinset isn't easy to 'smooth-trowel' in fact you can't do it like you would finishing regular concrete because it is just too sticky and a trowell won't skim-over the surface. Thinset also has a high shrink-rate but this usually isn't a problem when using it to fill. And yes it will stick to itself just fine.

You should fill with the thinset then the next day be prepared to use a 'rub-stone' to grind the thinset smooth cause you are going to leave ridges when you trowel it. Vacuum the dust, wet-sponge it and your ready to set tile. If shrink cracks develope overnight don't worry about them, they will fill-in when you set the tile.

Go for it.
 
  #3  
Old 04-20-06, 12:59 PM
Member
Join Date: Jan 2006
Location: USA
Posts: 3,502
Received 2 Votes on 2 Posts
You can use thinset to level the floor if its only out a little as you say it is (no more than 1/4"). Thinset will adhere to thinset just fine.

Your tile layout sounds fine.

Is this on a slab? If so whats the condition of the slab?

If it's a framed floor, what do you have for a subfloor? What size floor joists, spacing between them and unsupported span from below? How thick is the plywood and how many layers? Are you using a membrane or cement board over the pywood?
 
  #4  
Old 04-20-06, 01:24 PM
Member
Thread Starter
Join Date: Apr 2006
Location: CT
Posts: 9
Received 0 Votes on 0 Posts
Thanks for the reply Bud & Johnny,
Bud, I didn't realize I would not be able to keep the thinset smooth with the flat edge of my trowel. Like you mentioned, I pictured working the thinset similar to finishing concrete. Maybe I will "practice" on an old piece of plywood to get the feel of the thinset and see how well I can do with the leveling technique.
Johnny, my subfloor is as follows: 2 x 10' joists @ 16" on center with a span of 7ft. The subfloor consists of 3/4" plywood under a 7-ply, 3/8" plywood underlayment (similar to Halex plywood and is supposed to be as strong as 5/8"). This underlayment is screwed down every 4" on the edges and 6" in the field and does not penetrate through the 3/4" subfloor or into the joists. The original underlayment was 5/8" plywood which I removed to gain some height so my tile threshold will be even with the hallway. I was planning to install the 1/8" Schluter Ditra and then the tile, but in order to have a smooth transition to the hardwood hallway, I decided to install the tile directly to the plywood underlayment. I know I'm taking a chance and I will catch a lot of grief from everyone, but the area is a very small half bath and the floor is rock solid with no movement. Thanks for both or your comments and I'm sure I will have more as I progress.
Louis
 
  #5  
Old 04-20-06, 04:31 PM
Bud Cline's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2001
Location: Central Nebraska
Posts: 1,300
Received 0 Votes on 0 Posts
I decided to install the tile directly to the plywood underlayment
Well OK but I hope your plywood is 'exterior grade'.

You are aware that to do this you MUST use a beefed-up thinset. Just any old modified thinset wouldn't be recommended.

You should use a 'dryset' thinset and mix it with the additives yourself, this will produce more bang for the buck than a regular modified thinset usually does.

I would recommend using Mapei's Kerabond thinset with their Keralastic additive, the product works very well but don't mix too far ahead until you get the hang of using this mixture. It has a slightly different feel to it than modified thinset and excessive waste is just around the corner if you get too overzealous. The stuff is pricy and is the only mixture I would use tiling directly to plywood.
 
  #6  
Old 04-21-06, 06:20 AM
Member
Thread Starter
Join Date: Apr 2006
Location: CT
Posts: 9
Received 0 Votes on 0 Posts
Thanks for the info Bud,
I just checked the thinflex bag this morning, and it is Mapei Ultraflex 2. As far as I know I just have to add water, I really haven't looked at the instructions closely yet. I got it from a reputable tile dealer here in CT, the same place I got my tiles, grout, matching caulk, grout float, trowel, & spacers. I hope this is considered a beefed-up thinset as you suggest. As far as having a different feel to it than regular thinset, this is my first time, so I have nothing to compare it to. Thanks again Bud for all the help. I'll let everyone know how I make out.
Louis
 
  #7  
Old 04-21-06, 08:18 AM
Member
Thread Starter
Join Date: Apr 2006
Location: CT
Posts: 9
Received 0 Votes on 0 Posts
Bud,
I have a another question, would the use of Red guard on the plywood underlayment prior to tiling be beneficial in helping waterproof the floor just in case? It is a half-bath, so I don't anticipate any large amount of water, but just as an additional precaution. Is this overkill or are there any downsides. Thanks.
Louis
 
  #8  
Old 04-22-06, 11:39 AM
Bud Cline's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2001
Location: Central Nebraska
Posts: 1,300
Received 0 Votes on 0 Posts
Louis,

Ultraflex II IS NOT a high-powered thinset. Ultraflex II is a fine product and yes it is modified and you only add water.

For a higher level of confidence in your installation you should
use a 'dryset' thinset (un-modified) and mix it with the additives yourself, this will produce more bang for the buck than a regular modified thinset such as Ultraflex II usually does.

I would recommend using Mapei's Kerabond thinset with their Keralastic additive.

Read the Ultraflex label, if it says you can use it to tile directly to plywood then go for it I suppose, that way you can complain to Mapei if the you experience an adhesive failure.
 
  #9  
Old 04-24-06, 12:48 PM
Member
Thread Starter
Join Date: Apr 2006
Location: CT
Posts: 9
Received 0 Votes on 0 Posts
Bud,
I did a closer reading of the Mapei Ultraflex 2 thinset instructions over the weekend and it lists "properly prepared Group I exterior-grade plywood (interior residential floors and countertops in dry areas only)" as one of their recommended substrates. It goes on to say "do not apply over presswood, particleboard, chipboard, masonite, lauan, gypsum floor patching compounds, metal or similar dimensionally unstable substrates". I suppose I can always call the tile dealer and inquire about the Kerabond dryset with the Keralastic additive and why he recommended the Ultraflex 2 instead (he was aware that I was applying to plywood).

Would applying Redguard down on the plywood help as an additional waterproofing method and would it help or hurt the bond with the thinset?

One last question: When mixing the thinset (I plan to use a 5 gal. drywall compound bucket) it says to gradually mix the 25 lb bag to 3 qts. cold water. My plan is to start slow and mix maybe half or a quarter of the thinset. Its easy to measure the water, but how do I measure the thinset mix? Is is necessary to measure out the exact weights or just a rough guesstimate of how much a half-bag is? Sorry for the additional questions and thanks again for everyone's time.
Louis
 
  #10  
Old 04-25-06, 08:24 AM
Bud Cline's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2001
Location: Central Nebraska
Posts: 1,300
Received 0 Votes on 0 Posts
I did a closer reading of the Mapei Ultraflex 2 thinset instructions over the weekend and it lists "properly prepared Group I exterior-grade plywood (interior residential floors and countertops in dry areas only)" as one of their recommended substrates.
So does your plywood meet this criteria?

Can't answer your Redgaurd question because some plywoods contain resins and waxes and different products that could jeopardize the thinset bond as well as the Redgaurd bond. Tiling over plywood is just risky-business plain and simple.

I have never understood why those manufacturers do everything they can think of to promote Do-It-Yourselfers to buy and use their products and then they print instructions on the bag that would only suit a large construction project with 100 tilesetters all working at the same time. The people that work for those companies must be real morons is all I can figure out.

DON'T EVEN THINK ABOUT MIXING A WHOLE 50-POUND BAG OF THINSET AT ONE TIME. Those are stupid directions given by people that are out of touch with reality. SCHEEEESCH!!!

Start off with about 60 ounces of cold clean water in your mixing bucket then mix as you add the dry powder when the cocsistancy reaches creamy peanutbutter, stop. Let the mixture sit for about ten minutes then mix it again but don't add anything. This will give you about five (or so) inches of mixed thinset, once you get the hang of what you will use and how fast you will use it then you can adjust your quantities to suit your own pace.

I still say you should be using the dryset thinset and adding the additive (no water) yourself.
 
  #11  
Old 04-25-06, 08:56 AM
Member
Join Date: Jan 2006
Location: USA
Posts: 3,502
Received 2 Votes on 2 Posts
Louis

As Bud said a couple times here dryset and additive is the way to go over plywood. You are spending time and money to do this job and so you should take the right steps to make sure that it lasts.

Why not consider membrane options like Ditra or Noble CIS. They don't add much height at all and won't make much difference in your transition to the adjoining hallway. The odds on your transition height being perfect are slim anyway. You do have options to make the transition look good.
 
  #12  
Old 04-25-06, 08:59 AM
Member
Thread Starter
Join Date: Apr 2006
Location: CT
Posts: 9
Received 0 Votes on 0 Posts
Thanks for the reply Bud,

After reading your initial reply, it got me to start thinking about it and I wasn't quite sure my plywood met the exterior grade rating. As I mentioned in my earlier posts, it is a 3/8" euro-birch 7-ply plywood, and the reason I really liked it was because it is as strong as 5/8" plywood. I was doing so much research in strength characteristics that I totally forgot about the exterior rating, hence my question about redguard. After doing a little research last night on the internet regarding eurobirch, I found it has a marine rating and is used on boat interiors and exteriors. The specs on the product say it is made of phenolic resin which is waterproof and boilproof. So I think I am safe as far as the exterior rating goes .

Bud, I'm sorry if I keep asking questions, but I'm still a little confused on the mixing part of your previous email. You suggest starting with 30 ounces of clean, cold water to which I add thinset until it has the consistency of creamy peanut butter. This should give me about 5 inches of thinset to work with. If my math is correct the instructions on the bag say to mix the entire bag to 3 quarts or 48 ounces of water (which we both agree is ridiculous). Based on the instructions on the bag, wouldn't mixing 30 ounces of water be equivalent to using 2/3 of the bag of thinset? Or am I missing something here? Please, I hope this doesn't sound like I'm questioning your judgement, which I most definitely am not. I'm just confused on the water/thinset ratio in your instructions as compared to the bag instructions . I hope this makes sense. Lastly, and please feel free to tell me to shut-up at any time, can I use a stick to mix the thinset or should I purchase a mixing paddle? Thanks so much for your advice.
Louis
 
  #13  
Old 04-25-06, 09:47 AM
Member
Join Date: Jan 2006
Location: USA
Posts: 3,502
Received 2 Votes on 2 Posts
Louis

3 quarts = 96 oz.
3 pints = 48 oz.
 
  #14  
Old 04-25-06, 10:27 AM
Bud Cline's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2001
Location: Central Nebraska
Posts: 1,300
Received 0 Votes on 0 Posts
Louis,

Don't worry about all the questions, keep 'em commin' if you need to.

Now,
After all your research and all your calculations and high-math, now you want to mix thinset with a stick? GOOD -GOD!

Thinset isn't that easy to mix especially in larger quantities, you better be locating yourself a some electrical mixing aparatus.

Here's how scientific I get with mixing thinset. I mix my thinset in a 3-1/2 gallon bucket, never a five gallon bucket because you can't dip a trowel into a five gallon bucket and get the thinset out of the sucker. It's just too awkward.

I drink coffee. My helpers drink coffee. We buy our morning coffees in twenty ounce cups and we save the cups. At any given time you can open a door on one of my work vans and you will find a stack of coffee cups just waiting to go to work.

This is how I arrived at telling you to start-off with 60 ounces of water. That would be three of my styrofoam coffe cups. I start off with five coffee cups of water and then add a little more to arrive at 2/3 of a bucket of thinset when all is said and done. That would be too much for you to start off with though so I trimmed it for you.

We don't measure no stinking water and weigh no stinking thinset, we throw some ingredients in a bucket and go for it. Five cups of water (thereabouts) and dump some powder in on top. Mix it for a minute or two and adjust whichever way we need to go to get the consistency we want. That's how scientific this measuring of thinset is.

I can tell you that if you were to try to add fifty pounds of dry thinset to only three quarts of water you would have both wrists in plaster casts before the day was out using an electric mixer as we do.
 
  #15  
Old 04-25-06, 01:12 PM
Member
Thread Starter
Join Date: Apr 2006
Location: CT
Posts: 9
Received 0 Votes on 0 Posts
Thanks Bud and Johnny,

Johnny, I'm a little embarassed about my error in weights and measures, thanks for not rubbing it in . Now it makes perfect sense, based on Bud's directions, I'd use approximately 1/3 of the thinset, which is perfect for me just starting out. Actually, I'm also a little embarassed to admit that I have the Ditra sitting in the basement. It was the first thing I got when I did my tile research, but even with it being just 1/8" thick, it still puts my tile a tad to high with the hallway hardwood floor. I'm sure I'll put it to good use on my next tile project.....

I'm going to head to the tile dealer this afternoon and get the paddle mixer, always good to add another toy to the tool box. When I'm there I'll broach the subject of the dryset thinset with the Keralastic additive and see if he has it available and exchange my Ultraflex 2 for that. Thanks again guys for all the help and I'll let you know how I progress.
Louis

p.s. Bud, the point about the 3 1/2 gallon bucket is a very good idea, I'll pick up some of those as well.
 
  #16  
Old 04-27-06, 11:02 AM
Member
Thread Starter
Join Date: Apr 2006
Location: CT
Posts: 9
Received 0 Votes on 0 Posts
Laticrete 317 w/ laticrete 333 admixture?

Bud and/or Johnny,

Would laticrete 317 floor 'n wall thinset with the laticrete 333 additive be comparable to the Mapei Kerabond with the Keralastic additive? The laticrete products are available at Lowes and they don't carry the Kerabond thinset. This is to improve the bond with the plywood underlayment as you have suggested.

Louis
 
  #17  
Old 04-27-06, 12:56 PM
Bud Cline's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2001
Location: Central Nebraska
Posts: 1,300
Received 0 Votes on 0 Posts
YES Laticrete 317/333 is the same thing, basically.

I only suggested Kerabond/Keralastic because you said you had access to Mapei products. Use the Laticrete if you have it available to you. Toe-may-toe/toe mawh-toe.
 
  #18  
Old 04-28-06, 08:16 AM
Member
Thread Starter
Join Date: Apr 2006
Location: CT
Posts: 9
Received 0 Votes on 0 Posts
Thanks Bud..........
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: