I want to cover an unattractive brick hearth. It is somewhat uneven. If I tile it with 12″x12″ tiles the dips would be taken of. However, the dips may show through in the likely event that I use smaller tiles. Anyway, I’m considering the following steps:
Option A) Use some sort of concrete leveling compound to eliminate the uneven quality of the existing brick hearth. Cover the hearth with 1/4″ backerboard. Tile over the backerboard using either thinset or one of the “plastic” adhesives.
Option B) Forget the leveling compound and backerboard and just use thinset to level the surface and make the tile adhere.
Which is the better option?
Additional questions:
What adhesive product (thinset?) do you recommend for this high heat application?
Is backerboard a flammable or otherwise dangerous product to use as underlayment for a hearth?
Thank you for any and all advice.
-Steve Elias
Replies
Before you do anything, you should check your local building codes to determine whether they require some sort of airspace between the tile and combustible walls. Determining this will help you determine what installation method to use for the tile.
You need to make sure that whatever adhesive you use is rated by the manufacturer as being acceptible for high-heat installations. Typically, this would rule out all mastics and some thinsets as well. The mfg guarantee is crucial.
Assuming you don't need an airspace, to even out the setting surface, you would first apply a layer of thinset to the bricks which would act as a bonding agent. Then float a thin layer of mortar over the bricks to even everything out.
A very good explanation of this process is offered in Michael Byrne's fine book, "Setting Tile". If you don't have it, I recommend picking it up.
-Andy
Thank you, Andy. Based on your recommendation I've just purchased Michael Byrne's book. That, along with your advice, should see me through. Thanks again.
-Steve
I would not use thinset to bond the mortar.
I would apply some 3.4lb metal diamond lathe to the substrate (brick) with concrete nails and float about 1/2" of wall mud (pre-mixed) over the brick, using a screed strip and a level to make sure it is plumb. Once it is cured THEN use the thinset to bond the tiles to the mortar bed.
Steve, the mortar bed is exactly what you were thinking about, and is indeed a "concrete leveling bed"
Your second alternative is not very good. You would have a hard time getting the backer board to stick to the brick, because there would be no mechanical fasteners, other than some thinset. I guess you could try some concrete nails but that may be pretty dicey.
I'd stick to floating a mud bed. If you have any questions, please post them. There are a couple of dedicated tile BB's out there, that I could steer you to, like http://www.johnbridge.com/vbulletin/forumdisplay.php?forumid=1
Good Luck!
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927
Thanks, Boris, for both the advice and the link. This is only my fourth tile job, and first in nearly ten years, so I am grateful for all the help I can get before I start mixing mortar.
-Steve