What is the reasoning for embedding durorock in thinset on a plywood subfloor.Does it make the durorock surface one large “monolithe” even tho its spanning the plywood seams.The thinset cant really be used as a leveling compound can it.And if u put a layer of felt down first is this to act as an isolation membrane even tho the duro is screwed down to the plywood anyway?And a layer of thinset sticking to krinkly felt paper doing much other than making easier to tear the floor up later?
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Some say the thinset it to hold it up, bridge any voids, others say to hold it down.
Then you screw it anyway, so any voids will likely be sucked down with the screws.
I use trowel mastic, Jeff Buck uses PL, others use thinset.
I don't think TP is the way to go.
[email protected]
It's Never Too Late To Become What You Might Have Been
no I don't ...
I use thinset.
I'm old school man ...
at least ... old backer board school.
my vote is it fills the voids, so to speak. It all flattens out for one big cushion of support. Plus ... that's what the TCA says to do ... so that's how I cover myself.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
I was taught that Durock should be applied as an independent substrate for tile.
Screw only to plywood, never directly to joists. Framing will react to changes in moisture content/humidity.....not something you want affecting the tile.
Most of those who set CB in thinset, do so to fill voids.
I don't, and have never had any problems.
One way better than the other? Dunno.
J. D. Reynolds
Home Improvements
Thinset fills any voids between the CB and the ply to minimize any potential movement of the cement board.
There's a noticeable difference when walking on cb that has been thinsetted and screwed down and cb that has just been screwed down.
Thinset fills any voids between the CB and the ply to minimize any potential movement of the cement board.
Not being a dick but............what happens when you put a or several screws right where the void is?
Isn't that going to just suck the cbu down to the low point?
Eric[email protected]
It's Never Too Late To Become What You Might Have Been
I always thinset the duro down first. Strart the screws/nails at the perimeter and then the field with the same pressure on each fastener. I believe the thinset fills voids as it squshes into them being the duro is pretty ridgid especially within the small sections being screwed down. Plus I feel it makes the subfloor and cbu one grasshopper making it more substantial.
The debate I always get into is weather or not screws are better than roofers. I always thought cbu screws were better than nails but as one guy pointed out the fastener only holds it till the thinset dries then its the thinset that holds it down. Made sense to me so when I did this job this week in my mudroom (finished last night...whewww) I started with nails, then used some screws...I nixed the nails after abouta dozen or less. I'm still sold on using screws. Just feels like the righter route to go to me...call me old fashioned...just call me : )
Also I never screw into the floor joists...just the ply (in this case Advantech).
PS...I think Advantech is way more substancial than plywood I'm sorry to say.If Blodgett says, Tipi tipi tipi it must be so!
TipiFest 06~~> Send me your email addy for a Paypal invoice to the greatest show on earth~~>[email protected]
Those screws are a pain to get started though. I recently slipped off of one because I was putting too muck pressure on the screw. I put a nice square drive hole through my index finger. Star shaped cuts don't heal very quick."Oh, this is the worst-looking hat I ever saw. What, when you buy a hat like this I bet you get a free bowl of soup, huh? Oh, it looks good on you though."
Does anyone have a good reason to use 1/2" cbu on floors rather than 1/4", or is it more or less a decision base on any surrounding floor heights that you want to match."Oh, this is the worst-looking hat I ever saw. What, when you buy a hat like this I bet you get a free bowl of soup, huh? Oh, it looks good on you though."
Sometimes depends on the toilet flange height.....
I personally use 1/2 unless I have to use 1/4. It seems "stiffer" when done.
Oh, of course. The toilet flange. Never at the right height it seems. I guess I would choose 1/2" also if I could."Oh, this is the worst-looking hat I ever saw. What, when you buy a hat like this I bet you get a free bowl of soup, huh? Oh, it looks good on you though."
Edited 3/16/2006 9:59 am ET by xosder11
Been there, I have many star scars on my various fingers even one thru the web of my hand - ouch. Now I have my assistant smack the screws one time hard into the cb and let them stand-up like soldiers. I follow her up and screw them down, you'd be suprised how fast we can go. This works well with those dang new fangled deck screws also into that dang new fangled non-wood stuff.
Ahh, whack with the hammer. I'm jotting that one in my notebook for next time."Oh, this is the worst-looking hat I ever saw. What, when you buy a hat like this I bet you get a free bowl of soup, huh? Oh, it looks good on you though."
"Oh, this is the worst-looking hat I ever saw. What, when you buy a hat like this I bet you get a free bowl of soup, huh?
no... a stool and a corner.... reserved fer yerself no less....Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
I don't get it. Are you saying the tagline is played out? Cause I'll be the first to admit that it was.
just describing the hat...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
I didn't relize that it was a tag line...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
So......your calling me a dunce? Well, if the shoe fits ; ) My high school vice principal thought the same thing.
It is a Rodney Dangerfield quote from the movie Caddy Shack. But I just never got around to changing it or removing it.
Edited 3/24/2006 1:43 pm ET by xosder11
did I do good by missing the movie....Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
BTW, that floor looks like it's coming out nice. That is a lot of cuts you've made so far. Is slate difficult to cut?"Oh, this is the worst-looking hat I ever saw. What, when you buy a hat like this I bet you get a free bowl of soup, huh? Oh, it looks good on you though."
BTW, that floor looks like it's coming out nice. That is a lot of cuts you've made so far. Is slate difficult to cut?
~~~~~~~~
Slate cuts like butter. And believe it or not you can sculpt slate with a chisel...
Yeh...tons of cutting. I'll post some more pics in the Gallery this weekend when I seal it,
Thanks
####If Blodgett says, Tipi tipi tipi it must be so!
TipiFest 06~~> Send me your email addy for a Paypal invoice to the greatest show on earth~~>[email protected]
That floor looks sweet Andy! Very nice. You cut all of that?
What's going in the field.
And..........what's that slate called.
You and Buck both avoided the question. If you drive a screw right throught the middle of the "void. it's no longer a void, it get sucked down.
I for one dont see the purpose of any fasteners at all when using Durock on the floor.
It's just a big tile. thinset it down and walk on it, where's it gonna go?
Eric[email protected]
It's Never Too Late To Become What You Might Have Been
>>"If you drive a screw right throught the middle of the "void. it's no longer a void, it get sucked down."
You're right, it gets sucked down, but only down to the nearest high spot. The t-set fills any lows.
>>"I for one dont see the purpose of any fasteners at all when using Durock on the floor."
Y'know, you have a point there. If you can stick tile directly to plywood, what makes CBU any different? Should stick to the ply just as well. I'd never be brave enough to try that but I am lazy. I shoot FRH ring shank sheathing nails. Goes down fast. And unlike Andy, no holes in my fingers. ;-)
Now back to a nagging question. Does everyone let the t-set cure under the CBU before setting the tile, or do y'all just get down to business as soon as the CBU is down?
Thanks.
"A job well done is its own reward. Now would you prefer to make the final payment by cash, check or Master Card?"
You're right, it gets sucked down, but only down to the nearest high spot. The t-set fills any lows.
You're wroung. The durock has NO rigidity. If I put a screw, or several right into that low spot; that durock is going right on down to the low. Or the screw is going through the durouck.
It's a means of attatchment. I don't know where all this high low fill in stuff came from. It is NOT a floated floor, not by any means.
As for letting the thinset cure, I wouldn't worry about it. The plywood sucks the moisture out of it really quick. Ever try to move a sheet just a bit like 10 minutes later?
Eric
[email protected]
It's Never Too Late To Become What You Might Have Been
Don't mean to bust your chops, but any possibility that a floor has low spots between where the screws are? The sheet will suck down to the highs, but you still got lows between.
"A job well done is its own reward. Now would you prefer to make the final payment by cash, check or Master Card?"
Of course and I agree.
It's just that to me at least, some people are putting forth information that may lead one to believe that installing cbu over ply is going to level out your floor.
It's not going to happen.[email protected]
It's Never Too Late To Become What You Might Have Been
my line of thinking ...
is a full mud bed a better stick?
compared to plywood.
Sure it is.
and backer board is just the modern version of a full mud bed.
so the stick is better with backer compared to naked ply.
why U so stuck on "voids" ... the tset makes for a nice comfy bed for the backer to sleep on ... nice and cushioned ... I don't use screws ... I use plain old roofing nails.
I'm pretty sure after bashing in a coupla hundred roofer over the average floor ... the backer is plenty "set" ... squishing that backer into the Tset and filling any voids.
Plus ... what's wrong with just following accepted practice? If the tile and backer manufacturers ... and the TCA say they'd like their lawyers to find some Tset under my backer .... who am I to argue?
Not like it's a hard step to include ...
plus ... chicks dig it.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Just out of curiousity, for those who nail the CBU down because the thinset will set up and hold it, do you use ring shank nails on your sub floor if you're using construction adhesive?It seems to me that some are saying "belt and suspenders" is too much for tile but I'm guessing they still use it for sub floor.Just an observation.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
screws..
1st choice...
ring shanks 2nd....
you can't hit the joists all the time with the required pattern... screws...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
why U so stuck on "voids"
Cause it's getting tossed around alot on these cbu threads.
Without quantifying what a "void" is, there is no accurate means of determining just how big of a void the cbu will span, especially with screws driven into it.
That's all.
Just another day at BT. Andy descrided a good way of doing it.
And I would never use roofing nails.
Only screws.[email protected]
It's Never Too Late To Become What You Might Have Been
Man, after reading through this thread I have even more doubts about the floor I'm doing. Guy I work for insisted upon removing 1/2" plywood from the floor (it was under the 1/4" plywwod that the vinyl was on). When we got the plywood off, we found that the subfloor is only 1/2" OSB. Now he's installing base cabinets and then filling between them with tile backer--he usually nails with roofing nails, no adhesive or thinset. I'm worried about the OSB flexing (it has several unsupported edges that deflect and squeak when you step on them--boss says the tile backer and tile will stiffen that) and cracking the grout lines. We're putting down 20" slate tiles.
It's hard to get enthused about a job when every other thing is done wrong, IMHO.
Sorry, but this guy sounds like another "can't see it from my house builder".
YOu need a minimum of 3/4 inches under your CBU and I'm not happy with even that. I do have to say though that I feel better with 3/4" if it's Advantech. I just "feel" as though its a much more rigid board than ply is especially good if its PL'd down to the joists. Typically I like dbl half inch glued and screwed, in which case I wouldnt even bother with a CBU...just be sure the top layer of 1/2" is an exterior grade ply which is what works with thinset.If Blodgett says, Tipi tipi tipi it must be so!
TipiFest 06~~> Send me your email addy for a Paypal invoice to the greatest show on earth~~>[email protected]
That floor is toast.
The guy doing it is a hack.
At least you know better.
Why are YOU working for him?
Sounds like you know more than he does.[email protected]
It's Never Too Late To Become What You Might Have Been
Why are YOU working for him?
He's got the license. I was going to take the test to get my license, but after talking to so many people who said "Why bother" or, "It's so expensive to maintain a license, get insurance..." and so on, I didn't go through with it.
But after spending all day trying to get a three way switch to work, I was really wondering too. Last time we did a three way switch we had the same problems--took all frickin day running back and forth to the breaker box. This time I stayed in the basement at the box and he and I shouted back and forth. I know almost nothing about wiring, but at the end of the day was drawing schematics and asking why we couldn't do it this way! (I was the one who found a second light to plug into the second outlet to see when we had juice there. He finally took out one length of wire that was more or less bypassing the switch, and after making many other changes, he got out his tester and it does look like one of the new switches is bad--has juice going through even when it's off! (Could, of course, be wired wrong, but even I don't think so--I think we may actually have the wires connected the way they should be!)
Danno, not to give advice but one of my bosses would not let me touch electrical work until I could explain to him how to wire a 4 way switch. If your boss can't ahndle a 3 way without circus tricks, well . . . . You are smarter than him. Don't work for someone you can't learn from.
"A job well done is its own reward. Now would you prefer to make the final payment by cash, check or Master Card?"
Last night I sat and sketched and I'm sure what I propose will work and what he has cannot ever work. Unless I'm remembering the wiring wrong, he has 2-conductor wire (whatever you call that--black, white and copper grnd) running between three outlets he wants switched for lights (two on one side of the room and one on the other, so part of it runs under the floor). Then there is a 2 wire running between the last of these outlets at each end down to switches at each end. Then there is the 3-conductor wire (with the added red) going from a GFCI where the power comes from and under the floor to two outlets he wants always hot. Somehow though, he's trying to connect the always hot circuit to the switched circuit using the red wire. But the way I see it, the only switching that can be done is between the white and the black on the switched circuit, and that would make it always hot. (That explains why one switch shows current always running through it, no matter what the position.) The second switch may be switching between red and white with black to the circuit. I don't know how the power gets from the first circuit to the second, switched circuit.
What I proposed is to run two wire between power and the hot circuits. Run two-wire between the two switched outlets on one side, then black down to the first switch and white (along with black and red from the switched side of the switch) under the floor to the box where white continues uninterrupted to the switched outlet there and the red and black enter the switched side of the switch and the black exits the other side to the outlet. Then a jumper connects the power black on hot circuit to black on the three wire circuit to give it power, before the switches.
I may be wrong, but mine at least seems to be able to work on paper, where as I can's see how his could. (Mine is also simpler, and in my book, simpler is better.)
Sorry for the extended hijack, guess I could have started another thread.
Yeah, guess this is a hijack.
Anyway, real quick, I think what you are describing is right, but here is a diagram of the "simplest" configuration for a 3 way, er, 3 way switch that is. ;-) If you look at the wire between switches, it has two travelers (red & black) plus the neutral (white). That's why you need 3 conductor with ground for that wire. The feed black goes to the common of one switch and the fixture black goes to the common on the other. One of the travelers will always be energized, sw1 determines which one at any given time. Sw2 determines which traveler the fixture is connected to.
sw1 pole 1---traveler red-----------sw2 pole1
feed black---sw1 common sw2 common---fixture black
sw1 pole 2---traveler black---------sw2 pole2
feed wht-------------------------------------------------------------------------fixture wht
"A job well done is its own reward. Now would you prefer to make the final payment by cash, check or Master Card?"
First of all have did he break the tabs on the hot side of the receptacels to separate the switch from the always switched?There are dozens of different ways of wiring this.But this is the simplest one to describe.At one of the switch boxes run (I am assume all #14, #12 is the same, but I just wanted to pick one) 14-2 (the ground is always assume so that is black, white and bare) power into the switch box.From that box run 14-3 to the 2nd switche box.From the first box also run 14-3 to the receptacles.The At the receptacles the white is neutral and will connect to the "common" silver terminal. On the hot side (brass) break the tab off. And connect one to the black (alwasy hot) and the other to the red (switched hot). Do it right and use pigtails. Don't try and connect one wire to the screw and the other to the backstab (to feed the down stream receptacles whcih you can't do anywith #12).At the first switch the income power neutral with connect with the receptacle neutral. The income power hot will be pigtailed to the switch common and the receptacle black.The white (remarked with black tape) and red on the wires to the 2nd 3-way will be the travelers.The black (from the 2nd 3-way switch common) will connect to the receptacle red.
Thank you. I replied via email so as not to hijack this thread more than I have. Will talk to the "boss" and see if he'll listen if it isn't working by Tuesday. He gave me Monday off (probably sick of all my questions!). Like I said, he had an extra wire in there at one time, feeding the circuit from the other side and we kept blowing the circuit breaker. About that time I figured my involvement couldn't hurt!
Edit: Ooops--I clicked send via email, but apparently it didn't take--sorry!
Edited 3/18/2006 4:33 pm ET by Danno
Sorry if I was vague in my answer about low spots. I screw the perimeters first. I usually lay down enough TS so I can drop about three boards down at once then I screw the perimeters first (locking in the even layer of toweled on t.s) and making sure my seams are even in heights. I like screws simply because in a lot of cases I just feel better overdoing things especially when we're talking maybe fifteen extra minutes on a floor the size I posted in that previous picture. And no...that wasn't me that drove the bit through my finger by the way who ever said that.
With screws on more than several occasions I've backed them out because I felt the board "might" just have been a bad void although thats really rare.
The other thing is when I work over Advantech which I prefer yet that is only when I'm doing the subloor work as well there are rarely any voids if ever because Advantech is so incredibly rigid.
I too, as i said before feel as though the t.s under the cbu makes the subfloor and the cbu one solid substrate or at least as close as you could possibly ever get. Far as the fasteners go. I suppose you could say they act as clamps to give the initial support the boards need before the t.s is dry. Why do you clamp furniture joints together when you glue them? It also simply gives me a better feeling to overdo something like this than underdo it cause no matter where I do the job inside myself I CAN see it from my house!
I even started laying the tiles without backbuttering them being so many people keep telling me its unnecessary but once again I couldn't help myself. I pulled up the few I laid down and back buttered them...I know for a fact they stick so much better and yeh....I'm sure its not necessary in a lot of instances...it just makes me feel better knowing I'm doing the very best possible job I can do.......I will say this again as well. When I use mastic on walls its a rare day I'll back butter. I feel different about mastic adhesive than I do about t.s. To me, thinset is cement...the cbu is cement the tile is close as you can get to cement and together forming one solid cement board with ZERO voids if I back butter as well...but its not right or wrong..its just how i feel is all.Oh yeh..in the field I just set the 12x12's with full tiles.
I was gonna do a large pattern in the middle like one of the boarder sections I made but I thought that to be over kill in a house like this. Too formal looking. As it is the boarder isn't really this house but hey...its a home and its what I made a conscious decision to do to give it a lil' bit of that WOW factor so when you walk in the door you don't just walk right through. It makes you take a little notice and think that the builder actually cared about his work : ) unlike so may shlockers out there that give us all a bad name.
I cleaned the floor for the tenth time today. I'll do it again tomorrow and Saturday. Needs less washing each time and it also keeps the joints from curing too fast. Black grout sucks to work with. I figure it'll be cured enough by Sunday when I'll use a sealer on it then post some pictures of the finished product. No biggie really...just one of a zillion projects like that I've done in this house which is finally coming to an end. If I'm lucky I'll be completely done by 07. Its rough only being able to afford working alone and on occasion with one or two other guys here. My home equity loans are coming to an end.If Blodgett says, Tipi tipi tipi it must be so!
TipiFest 06~~> Send me your email addy for a Paypal invoice to the greatest show on earth~~>[email protected]
Im with u I back butter any tile over 8". Particulaily with these bigger and bigger tiles.Some of these cheap "box" tiles from say "El Cheapo" are warped and theres nothing worse than hearing that hollow feeling on a tile.Back butterying only takes a few min. more.
Oh and my Makita impact driver makes putting d.rock screws sweet.
It's just that to me at least, some people are putting forth information that may lead one to believe that installing cbu over ply is going to level out your floor.
It's not going to happen.
OK, now I think I see exactly what you mean. We're talking apples and oranges.
You're saying t-set under CBU won't level the floor if it's in really bad shape. How could I disagree with that.
I'm saying t-set under the CBU will help to support the CBU across any low spots (just to support it, not necessarily to level it). The low spots I have in mind are just the "normal" inevitable variations in a subfloor in reasonably good shape.
We're probably thinking exactly the same way.
PS: apologies to Andy for my mistake. Brain freeze on my part. ;-)
"A job well done is its own reward. Now would you prefer to make the final payment by cash, check or Master Card?"
Good deal. Have a great w/e.[email protected]
It's Never Too Late To Become What You Might Have Been
It's just that to me at least, some people are putting forth information that may lead one to believe that installing cbu over ply is going to level out your floor.
Not sure how much good it does on ply.....however it seems to help on floors w/ 1X6's.
That's probably a good application for cbu. To help "smooth" things out.
Eric[email protected]
It's Never Too Late To Become What You Might Have Been
Just a note about working on fresh laid TS.
As I understand the theory it goes like this. As modified is curing it creates what looks like crystalline hairlike building structure.
I've seen the pictures of it kind of like a snowflake building. Any way as the stuff is green this structure is prone to flex/break and then yu have lost that superior strength.
For the reason that you use it you should allow for reasonable cure time to obtain that strength.
Not to criticize but just the theory.
>>"As modified is curing it creates what looks like crystalline hairlike building structure."
Thanks Clay. Good to Know. I always have let it cure, but also always wondered if that was just a waste of time. Now at least I have a good excuse to let it cure. ;-)
PS: I have also jumped out of a perfectly good airplane. Blue skies.
"A job well done is its own reward. Now would you prefer to make the final payment by cash, check or Master Card?"
Great i started this thread and glad someone brought up question of cbu on floors.Unless its a really wet area what are the advantages of using it on floors.I mean i hate the stuff ; weight. the dust ;thinsetting the joints.
Well you asked me so I'll give you my answer. You'll likely get a lot of opinions.
I don't call myself a tile expert but I've set an awful lot of floor tile and stone and none of it failed (yet, knock wood ;-). I always use CBU over thinset under the tile (I use hardibacker -- the new stuff isn't as strong as the original when it first came out, but I prefer it -- just personal preference).
Despite warnings by the manufacturer (and anyone you'd ask including me) it's not "structural," but on the other had, just seat of the pants, er, shoes, it does seem to add add noticable stiffness to a floor and the physics behind why it would do that make sense (if you glued a sheet of anything to a floor that is relatively hard to compress and has reasonable tensile strength as Hardibacker does, it would add a good bit of stiffness). Even if you glued something to the floor that had almost no compressive strength, but reasonable tensile strength, it would stiffen the floor (glue a sheet of 24 gauge steel to a sheet of 1/4" ply. Now try to bend the ply in the direction opposite the steel. You'll see what I mean -- fiberglass works using similar principles to make strong boats, for example). So anyway I prefer Hardibacker.
CBU also allows sold adhesion of the tile, which helps prevent tile cracking and tile pops. So does plywood and a lot of guys swear by just plywood.
CBU also allows you to match or nearly match floor heights in other rooms. So does plywood.
CBU is water resistant and does not degrade in the presence of water. Most tile goes in places where there's water.
Hmm, what else.
Maybe it comes down to what works for you. Like I said I've done lots of floors and they're all still good. So I will stick with how I was taught and what works for me. That's probably what it somes down to.
"A job well done is its own reward. Now would you prefer to make the final payment by cash, check or Master Card?"
I don't particularly let the thinset cure before I set over it- the thinset under is usually thin enough, and there are enough screws in, that I'm not worried at all about the hardibacker moving after 15 minutes of being set.
And I do use a thin bed of mortar- I think I can take out some minor low spots, but the point isn't to get a floor dead level, it's to provide a good, water resistant backing.
zak
very nice floor... looks like a ton of time invested... doesn't matter if there is or isn't the fact that it looks like it is what counts (which 99% of the time means more time than anyone would think)
5 stars * * * * *
p
join the list of folk who call me stupid... but I've been using hardie soffit material for backerboard... i put it rough side up in a bed of notched ts and I use Galv ringshank nails vs screws... even the instructions that come with hardie products say nails...
I use the soffit materal only because of the size of the sheets... price wise (per sf) about the same as the 3x5 sheets but i can get it 4x8 and 4x10 sheets... less seams to deal with... and it just seems that if you can cover a floor in one sheet you should... or at least have as few joints as you can... I'm big on "spread'n the load... "
p
I wrote: Thinset fills any voids between the CB and the ply to minimize any potential movement of the cement board.You wrote: Not being a dick but............what happens when you put a or several screws right where the void is? Isn't that going to just suck the cbu down to the low point? EricMy reply: "Void" seems to be causing confusion. If you screw CB to ply, the CB MAY not be 100% in contact with the ply across 100% of the contact surface. Sure it will where the screws are, but between the screws there might be a slight gap between the two.Gaps mean possible movement of the CB, which on a floor can mean possible problems.Someone asked why screw, why not just treat the CB as a "huge tile" and just thinset it? Well, it's likely that the thinset bond between the ply and the CB will fail over time as the ply flexes throughout the years. With the CB having little structural rigidity on its own, failure of the tile could be next.I don't use thinset as a floor leveler. If the ply is not flat, the thisetted CB won't be either. Use a SLC then go over that with what you want.I see the thinset as preventing any flexing or up/down movement of the CB due to slight gaps between the CB and the ply. No flexing due to the gaps being filled with cured thinset. Sure the ply floor can still flex, and on top of that the CB will as well. But a floor done with CB thinsetted to the ply subfloor is somewhat sturdier, and even sounds more solid, than one without.The thinset is the mayo that holds two pieces of Wonderbread together. It's still just Wonderbread...but it's a little better than plain ole bread.My opinion.
Little late getting back aren't you? ;~)
I sincerely doubt that the bond between the ply and or cbu and thinset could fail over time unless someone did something VERY wrong.
And my point about defining or quantifying a "void" was right on the money as it seems many people were interpreting it in many different ways.
It's a sandwich for sure.
Did I see that you are going to JLC? See you on friday? I heard Mike's buying lunch.
Eric[email protected]
It's Never Too Late To Become What You Might Have Been
Yeah, I've been very very slow lately. Especially visiting BT. Just pacing myself, you know?I'm registered up for JLC, but unless I can change my schedule I won't be able to make it. I'm working on it, though.
Actually the bond between the thin set and CBU will fail. That is the point. It provides a separation membrane AND a small void filler between the tile and plywood. The plywood and joists expand and contract at a different rate than the tile, so keeping them apart is the reason for the CBU. That is also why you DON'T want to nail/screw CBU to the floor joists, just to the plywood subfloor/underlayment. CBU adds no deflection resistance to the floor, so it must be stiff enough before you add the CBU.Following all this will give you the longest lasting floor and a lifetime warrenty from Custom Building products if you use their products installed to their specifications.Kirk
And that is why I use screws. Although I can't guarantee if it'd be the ply-thinset bond or the thinset/CBU bond that would fail. If I had to guess, I'd say the ply/thinset would fail before the thinset/CBU bond would fail.Sorta preaching to the choir, Kirk. And I'm off-pitch as usual.<g> Mongo
Not sure on plywood. All my tiling so far has been on 1x6 sub-floor. But I would probably thinset it.
I use thinset, then 1/2 CB w/ screws every 8" or so. Then thinset for the tiles.
Feels like a slab when done. So far so good.
Tree:
I also use thinset under backer. There seems to be a debate about using modified versus unmodified thinset under the backer. What I've found is that using modified tends to "glue" the backer to the ply adding stiffness to the floor (acts as a monolithic diaphram). On the other hand, when the ply moves seasonally (not much, but even ply does move), it will try to move the backer and thus could crack the tile. I think TCA recommends unmodified under the backer, but I've never really resolved in my own mind which way is better.
As a related question when doing this, is it necessary to allow the thinset under the backer to cure before tiling? Or does everyone find it's OK to get busy right away?
I've always let it cure first, but I'm wondering if I am just wasting time by doing that.
Thanks. Oh, and best of luck with it.
"A job well done is its own reward. Now would you prefer to make the final payment by cash, check or Master Card?"
As a related question when doing this, is it necessary to allow the thinset under the backer to cure before tiling? Or does everyone find it's OK to get busy right away?
I AM NOT A TILE EXPERT......however,
I give it a day or two.
My theory is......if the thinset is "filling voids" walking around on it while wet will cause it to "squoosh" out of the voids, and as a result not be as "flat or as monolithic" as if left alone.
I try to NEVER rush a tile job. (Going for the max life span)
BTW...have always used "modified" under the CB in the past....so far....so good.
durarock is obsolete. dens shield is far superior and does not stink, nor is it dirty. It cuts cleanly and is impervious also.
Do you use thinset under your denshield, same as CB?********************************************************
"It is what we learn after we think we know it all, that counts."
John Wooden 1910-
Actually, Durock is still the premier sheet material (not quite as desirable as a mud job, but much easier to do) followed closely by hardiebacker. Denshield is nothing mnore than high priced sheetrock.
"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
Denshield is nothing mnore than high priced sheetrock.
You are obviously not very familiar with Denshield; it is much more than high priced sheetrock.
It is not made from the typical gypsum found in ordinary sheetrock. It is something different, although I have no authoritative analysis of it.
I would NEVER use it on a floor although I have seen it used for such. I wonder what the TCA has to say about this application?
It is a fine product to use above the "water line" (3' or higher) in a shower or tub when installed and detailed correctly followed by a professional tile job.
This product has been argued about to no end here. I think those who have used it judiciously have ok things to say about it, those whoo have not have all the negative comments.
Eric[email protected]
It's Never Too Late To Become What You Might Have Been
"Durock is still the premier sheet material (not quite as desirable as a mud job, but much easier to do) followed closely by hardiebacker"
You've never used ditra then have you.
Faster, easier, lighter, better results.
I won't use CBB on floors anymore. By the time you finish carrying those hefty panels upstairs, I'll be finishing up installing the ditra.
Edited 3/17/2006 7:46 pm ET by bigmtk
You've never used ditra then have you.Faster, easier, lighter, better results.I won't use CBB on floors anymore. By the time you finish carrying those hefty panels upstairs, I'll be finishing up installing the ditra.
~~~~~~~~~~
I love Ditra too but the price is ridiculously high and the availability is .....well its way hard to find unless you order it and thats another story $$$$ in of itself. Almost makes it prohibitive to use. Too much of a hassle to get it for most people and when you do order it you have to buy either a giant roll and ordering the smaller amt doesn't pay because all the tile supply houses by me want an upcharge for what reason I have no idea that makes Ditra even more expensive than it already is.
When I was coming back from skiing in Canada a few years ago I stopped in ####HD there and picked up exactly the amt I needed which was fine but HD or tile stores don't carry it here on L.I. Too bad cause it is real easy to use and seriously light to carry. Wonder whats up with the availability factor cause HD carries a lot of Schlüter-Systems cept Ditra.If Blodgett says, Tipi tipi tipi it must be so!
TipiFest 06~~> Send me your email addy for a Paypal invoice to the greatest show on earth~~>[email protected]
Where do I find the Ditra and what is the approx. cost? Thanks.
Where are you?
DalTile stores stock it, as well as other membranes. Any full-service tile store (not a big box) will stock some brand of membrane. It's something like $1.50/sf I think.
"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
http://www.tile-experts.com/products.asp?id=67
They are great to deal with, and will help however they can. Delivery was pretty quick.
"I am the master of my fate, I am the captain of my soul." Invictus, by Henley.
Looks like you got your question answered : )
Actually I wrote them today asking why they don't "Stock" rolls of it at local HD's here in NY on L.I like they do in Canada where you can cut off a roll as much as you need and not have to order it and wait for it and also pay delivary for it...
I'll post the answer I get from them if they in fact do answer. "No" supplier near me on LI stocks it at all and there's a LOT of big tile supply houses near me.If Blodgett says, Tipi tipi tipi it must be so!
TipiFest 06~~> Send me your email addy for a Paypal invoice to the greatest show on earth~~>[email protected]
The local HD, which is a dump anyway, has it as special order.But I was across town in the "rich area" and they had a roll of it on the floor.
Wish they had it at my HD dump on the floor..special order will cost ya a lot more and who wants to wait?If Blodgett says, Tipi tipi tipi it must be so!
TipiFest 06~~> Send me your email addy for a Paypal invoice to the greatest show on earth~~>[email protected]
Just a thought on the ditra. If you know you are going to use it, why not buy a large roll and use it over several jobs. The more you buy the cheaper it is per sf.
I wish I had stocked up on wedi board before the prices got totally ridiculous.
Yeh I spose' but you know how it is. You just wanna run up and pick up all the material at once. Thats the reason I wrote them asking why its stocked in such few locations. Makes absolutly no sense to me to market a product like this. Someone in their corporation isn't doing a very good job IMO. Thing too is...suppose I need two more sq ft than whats on ####roll? I have to order the bigger roll and have the remainder sitting around till my next tile job? I "hate" stockpiling left over material! Its hard enough keeping my shop organized with what I do need.And real estate is at a premium in my shop. Thats one great thing about HD. I can return what I don't use. Major big plus!!If Blodgett says, Tipi tipi tipi it must be so!
TipiFest 06~~> Send me your email addy for a Paypal invoice to the greatest show on earth~~>[email protected]
I have for 25 years tiled over a 2nd layer of plywood, PLed and screwed 6"oc each direction.
I use unmodified t set &milk for the tiles. never had a problem, except perhaps if you need to remove a tile it requires destroying the plywood.
Never understood the point of cb on a floor.
I don't know if you're talking about bath floors, but as a remodeling contractor (27 yrs), I've pulled up dozens of bathroom floors over the years that have been installed over plywood (or particleboard!) that have totally rotted through due to water infiltration around the perimeter or through failed grouting, especially next to the tub or shower.
I've always used CB in bathrooms, (set in thinset), and fill the joint next to the tub or shower with silicone or polyurethane caulk so that even if there is a grout failure, the moisture doesn't reach the subfloor.
I've met quite a few tile guys that tell me it's perfectly acceptable to tile over drywall ("as long as it's greenboard") in a shower, but, of course, that's what keeps me in business.
Greenboard in a shower is rediculous, but then I've seen plenty of rotted out showers that use cb. Why? Poor detailing and omitting paper behind the cb.
Cb sucks up water like a sponge, If you are getting that much water on the floor,cb will hold that water on the subfloor for about forever, now the subfloor rots.
Cb on the floor works well, I will contend that a second layer of ply is more rigid-stronger.
Poor design & details will foil either system
yeah, I agree that the devil is in the details. We use visqueen on the wall studs, run into the pan. Of course that's not going to work on a floor, so we try pretty hard to make sure no water gets beneath the surface.
Most of the older homes around here (prior to 1950 or so) have mortar bed floors with metal reinforcement, laid over diagonal shiplap subfloors. Of course, a lot of them have cracks too, which is one reason we're taking them out........
Do you use your plywood method in showers too?
Do you use your plywood method in showers too?
Dats a good one!