Blade's bathroom refresh

[qz78ws]

I'm back...master bath went well thanks to all the great advice mined here.

Starting the next bathroom project; a simple refresh. I am removing vinyl flooring that was actually in very good condition due to quality installation by previous owner's contractor. The subflooring is 1/4" wood underlayment over 3/4" T&G plywood. I plan to install porcelain over Ditra. Should I remove the 1/4" underlayment? The underlayment is in great shape, planar, and stapled on a 4" grid.

Thanks again to all.

[qz78ws]

Additional info...

The T&G plywood was nailed instead of screwed (house built mid-80s). There are a few minor squeaks but no detectable movement. If OK to leave the 1/4" underlayment, I could screw in spots through the underlayment/subfloor. Joist are real 2" x 10"s and the longest unsupported span is 6'.

Thoughts?

[Radas]

Blade,

Unfortunately, the .25" layer has to go. Providing the floor is rated for tile based on your specs (sounds like it, but double check the Deflecto at the top of the page in the blue bar), hammer down the remaining staples after removing the .25" layer, then use screws to affix the subfloor in the areas where the floor squeaks.

[dhagin]

What Ali said.

Only thing I'd add is screw the whole subfloor down to the joists with deck screws. Install any underlayment like this

http://www.johnbridge.com/vbulletin/...2&d=1265991838

If the joist spacing is 16" OC or less, and the subfloor is in decent shape, you can omit the layer of underlayment over the T&G. Another layer of plywood is always a good idea for a tile floor, but with Ditra may not be needed.

[qz78ws]

Thanks for the inputs. I pulled the 1/4" underlayment and screwed the T&G plywood as suggested.

Now that I got a chance to check, I have an area that slopes toward one wall. The slope goes from zero to 3/16" starting 21" out, all along the 66" wall. I have about twice the amount of modified thinset I need for under my Ditra. Can I apply some of this thinset as a leveler, allowing it to set before installing the Ditra? The tile are 12" x 24" porcelain. This is the wall that will have an antique dresser I am modifying for the vanity. No foot traffic along the wall.

Thanks for the education.

[Kman]

Thinset really isn't made for that application. You'll want to use either a floor patch or a self-leveling compound to bring that floor up.

Keep in mind, the floor can slope and still be flat, and flat is all you really need. However, if you can detect the slope, or if it may cause you an aesthetic problem with any part of the installation, it's best to get it back to level, or at least really close.

[qz78ws]

The attached photo shows a powder substance on the back of the tile I am ready to install. I am assuming a mold release. The powder transfers like dust onto my jeans, smears with a wet finger, etc. Should I wash the back of each tile?

Thanks.

[cx]

Absolutely.