We have 5/8" tongue-and-groove fir plywood then 7/16" OSB glued and screwed to the plywood. There are 2'x4'panels that are made from cement and can be screwed on the … WeÂve removed our old ceramic tile floors in the 2 upstairs bathrooms and are thinking of having 13" porcelain tiles with 1/8" grout lines installed for the new floors. Even levelquick, which claims on the package to work only after latex primer, on their website they say to redgard before the latex, then the level quick. RedGard waterproofing membrane is an easy-to-install solution to prevent water leaks through horizontal and vertical installations. Lets not over think this. joist with1/4″ Luan over it with peel and stick vinyl tiles on top of that. The problem with speed finish is that it doesn't work on OSB In fact, virtually no products are rated to work on OSB. Especially since I have redgard over the durock now. This took about 1 to 1.5 hours. 5) You can really just set the drain on the floor and rely on the mud beds to hold it in place. Schluter recommends using the un-modified between the tile and the Ditra. Drying time depends mostly on temperature & humidity levels and the surface will appear pink until the the RedGard has completely dried . This took about 1 to 1.5 hours. Using a 3/16"-1/4" (5-6 mm) V-notch trowel or 3/8" (9.5 mm) rough textured roller. Caulk the backerboard-to-window joints with 100% silicone caulk. West Fraser is a diversified wood products company with more than 60 facilities in Canada, the United States, the United Kingdom, and Europe. I have 1″ not 3/4″ osb as the sub floor and 24″ O.C. Put away the RedGard. The thinset is not adhering the CBU to the substrate. In cases where OSB is to be used as an underlayment on interior floor installation, it must be properly treated before the installation of tile. Use the flat side of the trowel and flatten the ridges to form a continuous, even coat of material. From responsibly sourced and sustainably managed forest resources, the Company produces lumber, engineered wood (OSB, LVL, MDF, plywood, particleboard), and other products including pulp, newsprint, wood chips, and renewable energy. Using RedGard under floor and wall tile will create a barrier that will be undisturbed after the tile is installed and grouted. Water damage prevention is active from both sides of the RedGard membrane. RedGard® as Crack Prevention Membrane. Tiling over plywood is a big no-no. There are other feathering products that are also a struggle with OSB. You said you were using Redgard, so make sure you have adequate thickness and complete coverage. Someone suggested using Redgard on the OSB to seal it prior to using thinset. Let this first coat of RedGard dry until the panels appear red in color. Like was said in a earlier post, all the thinset is doing is filling in the voids and slight irregularities in the OSB. I think that's an interesting option...but obviously only useful for painting, as it's colored and would leave a red finish (or hey, if one is using OSB for the industrial look, maybe a coat of redgard fits right in!) :) – DA01 Feb 9 '16 at 18:43 In theory, water should not be able to get through tile and grout, through redgard, through durock and into the greenboard for mold, correct? Force RedGard® into cracks with the flat side of the trowel, roller or brush. Take from someone that did it and regret it. If that is the way to go, then I need to know which thinset to use (latex-modified, or un-modified). Once the RedGard® is dry, tile can be safely installed to the RedGard®-coated OSB with one of CuSTOM®'s polymer-modified thin-set or medium bed mortars.