mortar or mastic for tiling tub surround?

Question

I will be installing 8"x10" ceramic wall tiles over cement board. Any suggestions on if I should use thinset mortar or mastic? Are there any advantages to using one over the other? I haven't hung the cement board yet.I believe that the Durock instructions say to leave the smooth side out for mastic, rough side out for mortar. Yet, I've also read that some people will do a skim coat of mortar before installation, doesn't that negate leaving the rough side out for mortar? I appreciate any advice.

Answer 1

Absolutely DO NOT use mastic or "PREMIXED" thinset [really nothing more than mastic] on your tub surround. Anyone saying otherwise doesn't know what they are talking about.

Mastic takes 6-12 months to "DRY" and after a year, the stuff will be fairly solid. Even after being fully dried, if exposed to a constant stream of water [don't think your grout, sealed or not, is waterproof, it is NOT] the stuff will re-emulsify. I have seen re-emulsified mastic, and it is not a pretty sight--it becomes a gooey mess.

here is one of many horror stories about mastic and showers [this is a tile forum run by a group of very friendly tile experts]: http://www.johnbridge.com/vbulletin/showthread.php?t=47930&highlight=mastic

go to this page and pan down to the last link on the first post:

http://www.johnbridge.com/vbulletin/showthread.php?t=5434

And do not buy the cheap grade of thinset, at HD buy the "Premium" Vesabond that costs about $16 a 25 pound bag.

On the skim coat issue. the pro's call that burn in. apply a very thin coat of thinset on the wall with a flat trowel, just before you load up and spread the ridges. It is intended to make sure you have 100% coverage on the wall [sometimes the ridged trowel doesn't get 100%]. I would also advise skimming the backs of the tiles if they have deep recesses. You want to avoid voids [air pockets] as much as possible.

You might want to look at "Redguard" while you are looking at the tile forum. it is a waterproofing membrane, in a can, that you "paint" on the CBU. Good stuff for the DIY'er

Answer 2

Tiling A Tub Surround

Answer 3

Mortar is best. Buzzards has the best technical answer.

Having said that, is it a surround for a tub only or is it going to be tile/shower combo. If you tell me that it only a tub, absolutely not a shower. Well, I've put in hundreds of tile surrounds on drywall using mastic for tubs only. With no problems. But it wasn't my choice, it was the builders.

But if it was my house, especially with larger tile than 6"x6", then I'd use Durock and mortar. The best brand is TEC Sturdiflex. The reason to skim is to insure full contact, and to lock the mortar into the open pours or the board. But you don't skim the whole board, then come back, but only skim the board in the section you are working. Spread the mortar with flat side of the trowel and then get more mortar and notch, with 8"x10", use 1/4" x 1/4" square notch trowel.

As far smooth vs. rough, do as the manufactors say.

Answer 4

Mastic Vs Thinset

Answer 5

This Site Might Help You.

RE:
mortar or mastic for tiling tub surround?
I will be installing 8"x10" ceramic wall tiles over cement board. Any suggestions on if I should use thinset mortar or mastic? Are there any advantages to using one over the other? I haven't hung the cement board yet.I believe that the Durock instructions say to leave the smooth side...

Answer 6

For that size tile over durock I would use the mortar. The skim coat is also referred to as a strike coat. It is applied in to the section to be tiled then immediately gone over with the notched trowel and mortar. This helps to insure that the mortar doesn't dry to quickly as that would create a weak set. You can also mist the durock first but a strike coat is better.

Answer 7

My sister is a professional tile setter and I work with her when I can. I'm learning the trade. She always uses mastic for tub surround and back splashes. When positioning the tile, adjust before you give it the final push, if you know what I mean. The glue will create a suction. If you move it around too much it'll slide. Use spacers to prevent sliding. The following day if some have shifted the mastic will still be soft enough to adjust and still be ready for grout. I think she uses mastic in these areas for that reason. Plus it's less mess than mortar.

Answer 8

I have just finished a DIY tub re-tile job. The tiles were 6x6 but its all the same really. What I used was the premixed tubs of tile adhesive. It was a little bit more expensive but worth it for not having to try and get any kind of mix just the right consistency. HD and lowes had great info and were help full in all stages of the project. They even cut a few of the tiles for me so i didn't have to rent a tile saw for just 6 cuts.
I followed the info in the pamphlets for the hardiboard and the adhesive/ grout manufactures and it has turned out great.

Answer 9

After installing thousands of sq. ft. of tile and remodeling more baths than almost anything else, I suggest you can use either. The mastik will set faster, and for that size tile I suggest you run the bottom course and let it set up.

Verticles are a bit more of a challenge in that they fight shear weight as well as the pull of gravity away from a wall.

I use both, and have always been OK with both, but Mastik will secure that sized tile in less time. So depending on which you choose will determine what side out/in

Steven Wolf

Answer 10

skim coat just levels out and makes it rough.. i use both mastic or thinset. i do a skim coat of mastic just to seal things up. your ging to get some sag with that size tile.. so make sure your first row is supported