Hello all,
Should I use 1/2″ or 1/4″ CBU for a bathroom ceramic tile floor (and why)? It is going on 3/4″ plywood subfloor, and I am planning on just screwing it down and not using a thinset to bond it to the subfloor so I can actually pry it up to replace it in 15-20 years.
I am thinking of using 16″ to 20″ tiles on a 45 deg angle for the floor as well.
Thanks much, Anthony
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Replies
the cement board only serves two functions: it adds height, so calculate which is better for you. And it provides a good bonding surface for the tile. It does not add strength.
Don't skip the thinset under the cement board. it is an important component. If you're thinking about removing the tile in 15 years, you better prepare the subsurface properly or it won't last that long.
20" tiles might be too large for a bathroom. The size of the tiles need to be in proportion to the size of the room. Diagonal layouts can help if the room is not exactly square.
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Edited 3/31/2008 9:44 pm ET by FastEddie
If you don't set it in a bed of thinset it will flex when you walk on it and your tile will crack.
Large tiles need a stiff floor to survive. You might need more subfloor and/or joists.
I've always like the feel of 1/2" hardi under foot, especially if your floor isn't super stiff. There is definitely a difference. Ditra feels even worse than 1/4" hardi.
Beer was created so carpenters wouldn't rule the world.
Thanks everyone, I'm going with the thinset uneder the 5/16 Durock.
There is definitely a difference.
no there's not.
not if it's done right.
1/2" or 1/4" ...
U have a layer of thinset ...
and a thin layer of concrete board ...
and another layer of thinset and tile.
U telling me you can "feel" that 1/4" difference in the "strength" difference of one quarter of an inch thickness of concrete board?
"Ditra feels even worse than 1/4" hardi."
sounds like someone should learn to run a trowel.
how's a mudbed feel to ya? Real squishy-like?
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
how's a mudbed feel to ya? Real squishy-like?
Well yeah! Here's your sign! That's why it's called a mud bed."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
You're on crack if you're trying to convince me there is no difference in under-foot feel between 1/2", 1/4" and ditra, especially on longer spans, those in the L/360 deflection range, 3/4" decking, and with the thinner tiles. It's simply a fact and the main reason I steer away from ditra on wood framing.
In small bathrooms it might not matter, but for larger rooms it does, at least it does to my clients, the architects I work for and with, the finish carps on our projects that see it first hand, and myself. I'm as sure about that as I am the sun rises in the morning and sets at night.
Beer was created so carpenters wouldn't rule the world.
3/4" decking,
maybe them architects should start spec'ing that 1 1/4" of subfloor that the TCA recommends ... then we'd be a little closer to agreement.
using your argument ... sure ... with absolutely no subfloor ...
just set some 1/4" and 1/2" over some saw horses set 16oc ...
then sure ... the 1/2" board might last a fratcion of a second longer than the 1/4"
and the ditra would be pretty much useless ... sitting there draped ove the horses.
But forgive me ... I was talking about jobsites where the builders and architects know that the TCA recommends that 1 1/4" of subfloor ... first .... and subfloor as in ... wood ... before you even get to the point of laying that backer board.
but if U wanna cheap out ... Ditra will warrenty their install over that substandard 3/4 ply. And no ... learn how to mix and trowel the thinset ... and lay the ditra ... and there's no more flex than with anything else.
but again ... shouldn't be flex to begin with.
that's why for the 1 1/4 recommendation of wood subfloor.
but hey ... wadda I know ... I smoke crack and follow the TCA guidelines and actually build a solid floor first. Silly me.
I just re-read ....
"and with the thinner tiles."
so now the tiles add strength to the floor too?
wow ... can we use 1/2" ply and 1/4" cbu's if we use thicker tiles?
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Like I said, you're making my point for me. We both agree that what's put under a tile, including decking and framing, affects how it feels when walked on.
How can I argue with you if you keep agreeing with me?
Nonetheless, this is a little like reasoning with someone on crack.
Beer was created so carpenters wouldn't rule the world.
I just re-read ....
"and with the thinner tiles."
so now the tiles add strength to the floor too?
So are you suggesting a blindfolded person couldn't tell the difference between walking on a thin ceramic and 1/2" granite, given everything else is the same? If so, you are on crack, need to get out more, or both.
edit: I'm hoping you eventually make the connection that how a floor feels is partially a function of mass.
Beer was created so carpenters wouldn't rule the world.
Edited 4/8/2008 4:43 pm ET by IdahoDon
I'm thinking you really need to learn to build a freaking floor if you think the finish materials add any strength and fix any deflection problems.
"So are you suggesting a blindfolded person couldn't tell the difference between walking on a thin ceramic and 1/2" granite, given everything else is the same? "
Yes. That is exactly what I am saying.
what do U do? Tell the customer if they don't want their house to shake when they walk across the living room they gotta upgrade to 1/2" granite tiles?
yeah ... I'm the one on crack.
yer way is much gooder.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
how's a mudbed feel to ya? Real squishy-like?
Jeff, you essentially agree with my argument that the thicker and more massive the surface the tile is attached to the more solid it will feel under foot. Go a step further and put tile directly on a 4" slab and both you and I would agree it feels more solid still.
Beer was created so carpenters wouldn't rule the world.
directly on a 4" slab and both you and I would agree it feels more solid still.
No sh!t, sherlock. That's cuz a concrete slab has essentiall zero deflection. Tile laid directly on a plywood subfloor on L/720 joists will feel a whole lot better than the same tile over 1/2" cement board on L/360 joists."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
I AM NEW HERE BUT I AM A REMODELER AND I WOULD RECOMMEND 1/2" ON TOP ESPECIALLY IF YOU ARE NOT USING THINSET. THERE WILL BE TOO MUCH EXPANSION IN THE FLOOR , OU SHOULD HAVE 1 1/4" 'S OF SUBFLOOR . HOPE THIS HELPS
>>> so I can actually pry it up to replace it in 15-20 years
Why? To me this is like saying "i want to remove the hardwood floor and replace it in 20 years" but it's your house.
It's been said many times before here, need at least 1 1/8 " of wood underneath, especially with big tiles. If not, you'll need to replace them before your 15 ~20 year expiration date.
"It's been said many times before here, need at least 1 1/8 " of wood underneath,"That is not what the TCA says.Now that is what is required for a F150 floor system with 16 OC joist.And for a F149 floor system it requires 1 3/8" (24" OC).But F144, F146, F170 systems only need 5/8"..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
"But F144, F146, F170 systems only need 5/8"."
and for no floor ...
U don't need nothing.
thanks for the help there Bill.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
This is the first I have heard of the F-system. Does it relate at all to the L/#### calculations?"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
There is no "F system".The TCA calls out the details for a larger number of different type of tile installaion systems. And they have catagorized them for reference.F - floors if I counted correctly there ar 34 different floors inclued interior/exterior, over wood, on conrete, balconies, roof decks, etc.RH- radiant heat floorsW - wallsC - ceilings (3xx) and countertops (5xx)B -bathtub walls ans showers.TR - removations (tile over tile and repacement shower receptors)P - swiming poolsS - stairsR reiferator roomsSR - steam roomsWS wubdiw stoolsTR - thresholdsRW - sound rated/fire rated wallsEJ - expansion joints..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.