How do I tile over knockdown drywall?

vangielover · 02-25-2010, 11:26 AM

What's the best way to install a tile back splash over a knockdown textured drywall that's already painted? I've heard just scuff up the paint to just flatten the texture and remove the paint. Anybody have any good ideas? Thanks!

Snav · 02-25-2010, 12:00 PM

For anything tile you need to use a thin backerboard/cement board - they sell it in 1/4" sheets. You can leave the paint on the wall if you'd like since you're just going to cover it over.

You shouldn't apply tile directly over drywall - drywall is not made for tile and might hold some tile for a while - but it flexes and bends, sags with time and the thinset (mortar like glue that holds the tile in place) might peel off the drywall paper and other such things - making your efforts to tile a waste in just a few short years.

So - put up the 1/4" thin backerboard, use a powdered thinset (comes in a bag - you measure out and mix up what you need as you need it) and do a careful job with the tile. Be sure to grout in between, wiping the tiles off as you work so the grout doesn't dry onto them (it just makes for an annoying cleanup when you're done), and then seal it all - frame around the outside of the tiled area with a nice trim if it's necessary.

JazMan · 02-25-2010, 01:33 PM

Snav,

Sorry, but I have to disagree with several of your suggestions.

First of all wallboard is more than a suitable surface to tile on to. AS LONG as the area is a dry area such as a backsplash. Not such a good idea for wet areas of course.

Second, 1/4" CBU is NOT for walls. It's for floors and counters.

Jaz

Snav · 02-25-2010, 01:42 PM

1/4" backerboard such as DensShield is quite suitable for wall-tile applications. DensShield is a backer board but it is not a cement board like Durrock.

The drywall, though, is my personal opinion from experience - take that or leave it.

JazMan · 02-25-2010, 09:40 PM

Denshield 1/4" is NOT suitable for walls, it's way too flimsy. Even if you installed it over wallboard, unless it was laminated to the wallboard. But, why would you? There is no need to use CBU's on vertical dry areas, and drywall is ideal for this kind of install, plus it's already there. DensShield panels come in a variety of sizes

• for walls and ceilings, use 1⁄2" or 5⁄8" thickness
• for countertops and floorings, use 1⁄4" or 1⁄2" thickness

More info @ gp.com

Jaz

josphill99 · 02-25-2010, 10:21 PM

whatever you decide to choose,don't be like me and buy what is the cheapest. I ended up having to tear it down completely and begin again because moisture got in and basically dissolved the drywall. big mess.

Snav · 02-26-2010, 08:04 AM

Sorry, Josphill, for derailing your thread.

Dairylander · 02-26-2010, 08:20 AM

JazMan is right. Drywall is a suitable substrate for a backsplash.
Sand off all the texture and you're ready to tile.

drywallIdaho · 02-26-2010, 06:23 PM

A new member here, but I would like to comment on the subject. The latter comments are absolutely correct in stating that drywall is a suitable substrate for tile in relatively dry locations. However, cement backer is a better substrate than drywall. Really, the difference in this case is durability. Tile on cement backer board is much more durable and resistant to water. Tile on drywall is durable when dry, but not very durable when it gets wet.

If you decide that you want the durability of cement backer, just cut out the area of drywall where you want to replace it with tile. Determine if your drywall is 5/8" or 1/2" thick and then install equal thickness cement backer in place of the drywall. You're then ready for tile.