Tim's kitchen: Plywood, Noble CIS questions... [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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03-07-2007, 01:34 PM
The kitchen & mudroom floors in our 80-year old house have been ripped out down to the 1x6 planking, on top of some very sturdy, true-dimension 2x10 16" o.c. joists spanning 12 feet (all okay with deflecto). So here are a couple of questions:

1) Plywood underlayment: We're going to install 1/2" plywood on top of the 1x6 planking. From searches on this board, it seems as though some recommend only screwing the plywood underlayment into the subfloor, while others recommend gluing & screwing. What are the advantages & disadvantages?

2) Noble CIS: Although expensive ($2/s.f.), we like the ease of installation and minimal thickness (1/32") of the CIS. How precisely do the levels between adjoining plywood panels need to match up in order to have a stable installation? If they end up being not exact (say, up to maybe 1/16" or so), do you recommend using a SLC before laying down the Noble CIS, or trying to make up the difference with thinset while setting the tile?

Thanks a lot!


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03-07-2007, 08:31 PM
Hi Tim.

Over a board sub-floor such as yours the plywood underlayment is only screwed down. No glue recommended there in order to maintain some degree of isolation between the seasonal movement taking place within the board sub-floor and the plywood underlayment layer on top.

Where glue is sometimes recommended is between two layers of plywood flooring. It this case a full spread glue can yield a stronger monolithic plywood floor. If glued incorrectly however, voids can be created between the layers and that would not be cool to have under tile.


03-07-2007, 11:00 PM

Very interesting... thanks for the helpful insight on that!