I currently am remodeling a master bath and have a tile installer that I'm not so sure about. He laid the durock and has started laying the floor tiles. I thought he was supposed to tape and float the joints of the durock but just realized that he has not done that. There does not appear to be any silicone or anything between the joints. I assume this is a problem and need him to correct tomorrow if needed before he goes any further. Is this necessary and what are the options.

Thanks so much for your quick response.

Hi Susan...

Joints of cement board MUST be taped and floated using a latex or acrylic modified thinset mortar just as you suspected, however, some people choose to do it beforehand (me included) and some people choose to do it as they are tileing...

And here's even more info. is this guy setting the cement board in thinset mortar or a construction adhesive before he installs the cement board itself to the subfloor? He should at least be using a basic construction adhesive (All cement board manufacturers require this step to warranty floors... also reduces creaking/voids) before laying the cement board down.

So, steps are:

1) install thinset mortar or a construction adhesive to subfloor
2) install cement board and screw it off with alakali-resistant screws
3) tape/float joints
4) apply latex or acrylic modified thinset mortar to cement board for tile
5) install tile, etc...

Rules don't change much for walls (except can use different adhesives).

Is this person doing floor and walls? If doing walls as well as floor then I suggest that he should tape/float the joints and also fill the void between the tub and the cement board with latex or acrylic modified thinset mortar.

Make sure this guy is laying down an alkali-resistant tape and that he fills the joints as required. If not then you can direct him to this DUROCK INSTALLATION webpage to show him that all steps outlined above are required!

Click on this link:

http://www.usg.com/USG_Marketing_Content/usg.com/web_files/Documents/Installation_and_Appl_Guides/DrckCement_Board-Installation_Guide.pdf

Let us know how it goes for you...



MARK

If your installer did 4 out of the 5 steps and skipped step 3 it is a sign of poor workmanship or laziness. The floor could be fine but it would have been better if all 5 steps were done. Mark might have left out a word in step #1, use the same modified thinset in steps 1,3,4 and 5.

YUP... I left out latex or acrylic modified at #1... ;) Thanks.


Bob... did you notice absolutely no posts yesterday at home improvement? What's up with that? And on a Sunday?

I only briefly check the desk yesterday, out of town and using dial up so I missed that. Most requests come before the weekend rather than the end when everything should be done. Who knows