View Full Version : Alkaline resistant tape
Houston Remodeler
So call me cynical but I couldn't see any real difference between plain old white fiberglass drywall mesh tape and the new grey "alkaline resistant" grey tape now offered by your better big box stores. Fiberglass is fiberglass right? :scratch:
It seems QEP is now offering 50 feet of the white drywall stuff for $3.97 (http://www.homedepot.com/h_d1/N-5yc1v/R-/h_d2/ProductDisplay?langId=-1&storeId=&catalogId=) stating ASTM D test results : 0 , whatever that means.
The grey stuff is priced very high compared to the old drywall stuff.
So I took it upon myself to cut off a section of drywall tape and soak it for a spell in bleach. Since household bleach has a pH of 12, and thinset runs around 11.2 to 11.4, I figured it would be a decent test of sorts. After a few days the fiberglass tape seems to have not changed one little bit. Occasionally I take it out of the bleach and tug on it in different directions.
From now on I'll be using my very inexpensive, regular, old-fashioned, plain white, fiberglass, drywall tape to tape the seams of the little CBU we install.
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Houston Remodeler
I tried to research the website of the grey tape manufacturer but couldn't find any specifications that would indicate anything other than their promise they grey stuff is somehow different.
Tiger Mountain Tile Inc
Very interesting. What I don't like about the grey stuff is it doesn't stick as well as the "regular" mesh tape.
You're doing some intriguing studies and have data to go along with them. I'm curious, you're not going for Cx's job, are you? :D
Houston Remodeler
Nah,
I don't have the legs for it.
:stick:
cx
stating ASTM D test results : 0 , whatever that means.Doesn't mean anything in this context. I think it's one of the many mold tests, or mold growth support tests, or similar. You could make your mesh tape outa mold spores and the wouldn't support mold growth within cementitious thinset mortar, eh?
The Portland cement might not have much effect at all on the fiberglass, Paul, but it might well effect the material they use to bond the fiberglass into a mesh. And that could be a problem, at least long term.
You wanna use your stuff in your work, that's none of our bidness, of course. But please don't be advocating it for use by our visitors inna shallow end, eh? :)
tilejoe
I've done the same in the past, Paul. I thought fiberglass is fiberglass.
cx
Tilejoe and Paul goin' straight to hell! :D
Houston Remodeler
My hand basket is a 2 seater.
dlarrivee
Sure seems to be a lot of un-scientific skepticism around here...
Higher Standard Tile
I like the grey one, it seems tougher to me than that wimpy white fiberglass tape. And I find it plenty sticky.
tileguynky
You mean we are supposed to be using the tape?:nya:
Cain
I have wondered this same thing myself for quite sometime.
the drywall stuff at the box stores says nothing about alkaline resistance, so I stay clear of it. the grey stuff is pricey for a small roll, so I buy it only when necessary. my tile store sells rolls of Bartwalt tape that looks and feels the same as the stuff in the drywall isle , but says alkaline resistant on the roll. so i Buy a roll every time I buy cbu.
gueuzeman
Use a SURFACE MEMBRANE, IT DOESN'T MATTER WHAT'S BEHIND IT, ORT WHAT cx SAYS. :nya:
oR EVEN IF YOU'VE HIT THE CAPS LOCK.
.
Cain
well i do Jim, but I still tape the seams before. and I suppose it doesn't matter as much, but it still makes me feel good to know I am doing things to manufacturer specs....or wasting time :suspect:
gueuzeman
I am in hell waiting for Paul and Joe.
I have beer!
.
tiletime56
:corn:No comment! HELL YES
koihito
I'll admit to using drywall tape at times. I've seen some mesh that is a bit more robust, but most of the "tile" tapes have no visible difference.
Out of curiosity, CX, what possible difference could the glue make once it's embedded in thin set? It seems to me (of course, that could be my problem right there :) ) that if you could weave glue-less tape together and get it on a joint it would still serve it's purpose. Paper drywall tape has no adhesive...
cx
Same reason welded wire mesh wouldn't work in deck mud if it weren't welded at the joints, Nate.
TileArt1
Alkali (it's alkali resistant, to be anal :D ) is a soluble base which chemically releases hydroxide ions (OH-).
Alkali, even in concrete-based products such as thinset, still release hydroxide ions after the thinset is cured. These hydroxide ions can chemically bond with any products it comes into contact with if the atom of that product has an overall + or neutral charge.
The glue holding the fiberglass mesh together may be one such product. Once that happens it changes the chemical makeup of the glue itself and alters it to (literally) be something other than a glue which will hold the mesh together. If a product is advertised as 'alkali resistant' the glue, or any other chemical products in it, likely have a negative overall atomic charge - the hydroxide ions cannot chemically (atomically) bond to it. This means the glue will stay glue.
It's like water coming into contact with salt - salt dissolves. Alkali coming into contact with that mesh may cause the glue or the mesh itself (coating, etc.) to dissolve.
Lecture over. Pop quiz in the morning. :D
Houston Remodeler
So y'all are telling me the fate of my tile job rests on the 'glue' that holds the grey tape together???? :eek:
I would think its the 'mesh' part of the fiberglass mesh, glue or no steenken glue.
cx
Give the quiz now, Professor! You ain't scarin' moi. :D
koihito
CX, I'm sure I'm wrong but...
Welded wire mesh is welded to keep it all together. If you could lay it out a strip at a time say, like rebar, would it not still do it's job? School me please :)
Roger, it sounded plausible until the end when you had to start theorizing and make stuff up! :foilhat: :D
TileArt1
Just to be clear - I'm not positive that's WHY you need alkali-resistant tape on your backers, but that's why an alkali-resistant tape would be made. Seems it's likely interrelated in some manner.
CX, your homework is to find yourself one Dave Gobis to 'splain this to us knuckleheads. :D
cx
Welded wire mesh is welded to keep it all together. If you could lay it out a strip at a time say, like rebar, would it not still do it's job? School me pleaseUnlike concrete reinforcing rod, Nate, welded wire mesh uses slick wire.
Re-bar has raised ridges that use the high compressive strength of the concrete to prevent any lateral movement across the face of the bars. Put those in each direction and you add substantial tensile strength to the cured slab or beam.
With the wire mesh, the only "grip," if you will, is when the deck mud (or concrete, of course) encounters the perpendicular wire periodically. You get essentially no friction advantage at all longitudinally along the wire.
Roger, I know how to find Mr. Gobis on most days, and maybe that's just what we need here. Of course I'd never bother him on a Sunday evening, :D but I'll see can't I get his attention for later, eh? :)
Houston Remodeler
What you just posted underscores my point - fiberglass being all micro sharp and angular, like mini rebar
or is that just wishful thinking after having been in my attic tonight?
cx
Could be, Paul. I ain't never microscoped any and also don't know what it looks like after a failure. And you know we've had failures or all the CBU manufacturers wouldn't require it, eh?
Kinda like pewtin' mud under the panels; if they thought they could handle the failure claims without that, they'd surely not recommend it.
dhagin
I am in hell waiting for Paul and Joe.
I have beer!
Welcome new guy, i didn't see you come in. And i have cuban rum, so there. :D
And you know we've had failures or all the CBU manufacturers wouldn't require it, eh?
So, yer sayin marketing isn't part (or all) of the equation? :)
cx
Not when all of'em do it, Dana. If any one of'em thought they could get away without it, there'd be banner ads announcing same!
Well, until the others determined they could get by without it, too.
And yes, I do understand that Marketing writes more of the technical information than the Technical department in most cases. :)
eurob
Paul ,
From '' reliable sources''
Self-adhesive drywall tape:
This tape is widely used in joining plaster plates, mending drywall cracks and piecing together and making up different kinds of plates. It goes on faster, adheres better, and requires no pasting or stapling. It won't tear, shrink, stretch or bubble, while it hides joints, cracks and holes permanently.
The product is woven with C-glass fiberglass and is treated with a coating and contact adhesive material. Characteristics are high tensile strength, good dimensional stability, stability to temperature, good elasticity, capillary action, and corrosion resistance.
Alkali resistant mesh :
After surface treatment, this alkali-resistant mesh has excellent properties including water-resistance, alkali-resistance, flexibility, softness, and resistance to aging. It is widely used for waterproofing in roofing applications, reinforcement for natural marble, plaster board, artificial stone material and Exterior Insulation Finishing System (EIFS).
Here is an interesting article http://www.duratape.com/fiberglass.php, the ending is pretty rough , but it gives a good image of why the industry creates '' new '' products . Just a thought.
Houston Remodeler
Thanks for the link Roberto. It underscores my point as that particular manufacturer calls their drywall tape "alkali resistant" too.
Now we can argue over just how much alkali resistant drywall tape is, as my sample sets in a glass of 12pH bleach with no change after a week.
dhagin
Now we can argue over just how much alkali resistant drywall tape is, as my sample sets in a glass of 12pH bleach with no change after a week.
i back my jobs for life, so a week means little. :)
Houston Remodeler
I'll let it set longer, the test has been 8 days so far. I'll move it to the work shop so it can set for a month or so. How long would be good?
Tiger pilot
Roger from Ft Collings (TileArt) hit it perfectly I believe - most mfg's request the special tape due to the adhesives holding the tape together so our tile setting materials don't affect them and cause tape failures. That is at least what I've been told at the mfg's that I've worked with.
As for drywall mesh tape - my understanding is the mud is a much different PH and other requirements so it doesn't work for tile setting materials and can cause the failure to stay attached to the backer board panels.
Steve R.
Houston Remodeler
Steve,
What is the pH of drywall mud? Both hot mix and pre mix... :suspect:
koihito
I've probably picked the wrong side of this fray but I have yet to find or be shown anything from anyone that amounts to evidence save Paul's little experiment. So far all we have is speculation, even from Steve :stick:
If you want to learn more, please visit our website Alkali Resistant Fiberglass Mesh Seam Tape.
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Houston Remodeler
Nate,
That's my point exactly. Aside from CBU manufacturers saying 'use alkali resistant tape' there seems to be no qualifications of what types of tape qualify as 'alkali resistant'
Tiger pilot
Paul I'm not involved in the drywall side of USG's business so I have no idea what makes drywall mud different (and therefore the tape different) from tile backer board tape - I'm just told it is by the folks at our Research Facility.
I'd suggest there IS REALLY a difference or else we'd be selling the same tape product to both uses rather than a double inventory and double sku to keep track of.
To the best of my knowledge ALL backer board mfg's do require the same basic tape for their warrantee and I can't believe they would all follow each other without some good reason - if nothing else to have a marketing advantage over the others!
Steve
cx
I'd suggest there IS REALLY a difference or else we'd be selling the same tape product to both uses rather than a double inventory and double sku to keep track of. Which is what I tried to 'splain'em yesterday (post 28), Steve, but it carries more weight comin' from a guy who has represented more than one such manufacturer. :)
I'm sure there's a standard and a test method out there somewhere, but I ain't got a clue. Surely y'all (USG) have someone up yonder in Chicago who knows that right off the top of his head, non?
Tiger pilot
OK, CX - you win! I will put the question to the rocket scientists at Research and see what they come back with. It may take a day to two to get their heads out of the clouds and answer emails :)
cx
Now, now, you be nice to yonder geniuses, Steve, we need'em. :)
Tiger pilot
Be careful what you wish for: From the first response:
Almost EVERY tape is a different product (from our in-house testing info) and vary greatly by mfg.
There absolutely are differences in tapes. What I will address pertains to our USG Durock tape only! We make our tape from the same fiberglass materials that we use for the mesh on the actual backer boards. We just strip it down into 2" and 4" bands for taping the joints. Therefore, (A) the fiberglass strands are thicker and stronger, (B) they are coated with an alkaline resistance material to protect those glass strands, and (C) the material ties into our board perfectly to complete the structure when the seams are taped properly.
Why coat them? Ceramic tile setting materials are cement based - very high in PH - some upwards of 12-15 on the scale and when combined with water over time it will destroy the fiberglass strands if they aren't coated. Drywall mud (USG is the worlds largest producer of that product) is PH neutral - so it needs no protection of the glass strands - PLUS the glass strands are weaker and thinner - so the lower pricing you see on drywall tape. HOWEVER, it will, over time, fail when exposed to cement based setting materials.
Someone said that there is a "DRYWALL" alkaline resistant tape - my lab guy isn't aware of any in our testing - when drywall folks want mesh tape they don't need the alkaline resistance so it isn't actually there. If you need the alakine resistance coating then it does become cement based tape and can be used for tile as well as exterior stuco types of materials.
Finally for CX and all you other standard based knowledge folks out there - no word yet on an ANSI or ASTM standard on the mesh or tape - but that can and will be looked at tomorrow.
Cleared up?? No more hard qustions tonight please - my brain is tired!
Steve
Tiger pilot
Just to throw one more log on the fire!!
There is also a huge difference is screws to hold the backer boards down - not only the coating for alkaline resistance, but also the grade of steel and the thread pattern.
Bottom line for the installers is why take a chance on failure of a big $$ job over a few cents difference in cheap tape or screws? It just don't make good sense!
Steve
eurob
Steve,
Can the durock interior tape be used with tile setting materials ?
Ceramic tile setting materials are cement based - very high in PH - some upwards of 12-15 on the scale and when combined with water over time it will destroy the fiberglass strands if they aren't coated..
Do you mean , that the tile setting materials once cured , continue to damage a regular , non protected , fiber glass mesh ?
cx
Bless you, my son, and may none of your thinset mortar ever exceed 14 on the Ph scale. :D
See, the Geniuses can be very helpful at times. We thank both you and them. :)
eurob
Cx ,
I didn't know that I have to take a chemistry course ....or just go the my swiming pool dealer to have my thin-set checked for the PH .:D
Tiger pilot
Reberto
If it is a USG made tape, and say's Durock on it, and alkaline resistant then yes you can use it on any tile or stone work.
If it is a USG drywall tape you should not.
Another quick note (2nd rocket science reply) our mesh is woven, so our Durock tape is woven, while drywall tape mesh is not.
One other report - we believe there is an ANSI specification on the tapes but believe it applies only to the required tensil strength under certain drywall use conditions - meaning it most likely won't apply to backer board tape uses. Again he will look it up tomorrow. I'm in Dallas, TX for the next several days for TCNA meetings so I will post the final results/info when I can.
Steve
CX - we do expect YOU to take the chemistry courses AND go to the pool supply to get your materials tested!! :) John Bridge still get's his "PASS" due to lifetime achievements in tile installation......
cx
Don't need no steenkin' pools supply. Don't think I have any of the little litmus strips used for testing concrete surfaces, but is only 'bout five miles to the local redi-mix company and a fella there will gimme some do I need'em. :D
Thanks again for your help, Steve, we really do appreciate it. :)
Houston Remodeler
Thanks Steve
Levi the Tile Guy
Back to Gueuzes point. If you are going to apply a liquid over the CBU you would still need an alkali resistant tape because you are still putting the tape on with thinset. If the tape were to break down in a traditional shower build you may get a few cracked tiles probably just cracked grout. If you had a break down on your seams with a liquid over them you could have much worse problems
dhagin
Thanks Paul & Steve. Paul for asking, and Steve for digging deep and keeping us edumacated.
My brain hurts now too, so no more hard questions for me either. :D
gueuzeman
I think I'm gonna read all 4 pages again. Maybe twice. Over a fresh beer, down here in hell.
.
Houston Remodeler
This all means that I'll have to raise my prices to cover the costs of that purdee grey tape I'll be buyin'
koihito
Fine, you win :nya:
gueuzeman
For me the real answers are either kerdiboard or Hydroban and fabic.
.
Tiger pilot
Hopefully the final answers on this:
ASTM C 474 is the spec on drywall mesh tape and also outlines the testing requirements and procedures for the performance
ASTM C 475 is the spec for Alkali Resistant Tape for use in "cement based coatings" applications - like ceramic tile or stone work.
As we all seemed to agree earlier, there are actual differences in the tapes designed and sold for drywall and tile applications. As I also stated earlier, USG has extensively tested many different mfg's tapes and found very large differences between brands and quality.
As with most everything else in our industry, the installer needs to be aware of many small details to insure a long lasting quality installation.
Steve
Hank B.
I most certainly hope nobody read this before steve was kind enough to join in, and offered someone a proposal that included drywall mesh instead of cbu mesh... ok I did, Now I've either got to go back to that customer and tell them that that it's now going to cost 2$ more, or absorb that cost myself. :bang:
cx
I don't have access to the full text of either of those tests, Steve, but C-475's title says it's: ASTM C475 / C475M - 02() Standard Specification for Joint Compound and Joint Tape for Finishing Gypsum Board. And not a hint in the abstract that would indicate it had anything to do with CBU or cementitious materials.
Maybe you can get them geniuses to give you more hints or, perhaps, send you or me a copy of the part of that particular test description that deals with cementitious mortar or alkali resistance? I mean, when you ain't got nothin' more important to do, of course. :)I most certainly hope nobody read this before steve was kind enough to join in, and offered someone a proposal that included drywall mesh instead of cbu mesh... ok I did, Now I've either got to go back to that customer and tell them that that it's now going to cost 2$ more, or absorb that cost myself.Hank, I'm sure anyone reading on this forum would already have been following the published industry standards and manufacturers' recommendations and would not have encountered any such bankruptcy-inducing charges brought about by following any heretical suggestions made earlier. Our people are just a little smarter than that, eh? :shades:
Well, OK, most of'em, then. :D
John Bridge
Backerboard tape installed with the idea of covering it (and bonding it) with liquid membrane really doesn't have to be installed with thin set. It's self-sticking to the point that you cover it up. I would still use the ten dollar stuff instead of the five dollar stuff. :)
Also, even if we can't find a standard we have manufacturer's specs/instructions and the handbook. So there's no excuse for all you cheap b . . . s fine mechanics to use the inferior drywall tape. :D
Hank B.
Well cx, I was hesitant to change from the alkaline resistant tape but pauls testing method seemed sound. Only honorable solution is to eat the extra 2$, the wife was pissed though. Looks like the kids will have to settle for community college instead of harvard though.
cx
Kids prolly woulda learnt nothin' at Harvard 'cept about illicit drugs and equally illicit women, Hank. Looks like we mighta actually saved not only your money, but their very lives, simply by following tile industry standards and manufacturer's recommendations.
A lesson well worth the learning, say I, and Mrs. Hank will certainly see it that way when you 'splain it properly. :)
scut207
and equally illicit women
Agreed on the drugs, but as much as I wrap my brain about this issue, I am still trying to picture the downside...
cx
Oh, I claimed no downside, Brian, just tryin' to help soothe Mrs. Hanks concerns, is all. :shades:
Besides, with proper training, them kids don't gotta go no place 'spensive liken to Harvard to learn about them kinda wimmen, eh? Hank aughta be able to home-school'em on that. :D
Higher Standard Tile
Well if Steve from USG is still following this thread, I have a somewhat related question.:jacked:
I use the Buildex square tipped screws that are designed for hardibacker when I hang Durock. The screw are coated just like the cbu screws but have a square tip which I find much easier to use than the phillips tip on cbu screws.
The only difference is that cbu screws have a slightly bigger head. So I add a few more of the hardi screws than required to be safe.
Am I causing a problem? And can somebody start making cbu screws with a square head? It is so much better.
http://www.itwbuildex.com/gcs_backeron.shtml
http://www.itwbuildex.com/gcs_rockon.shtml
Hank B.
Illicit drugs and women? Thought that was the point of college? As for screws, I used the coated ones with the self drilling tip and the torx head from ace ever since trying them it's all I use now. I'll get the actual brand name later when I can find the box.
Houston Remodeler
Backer-ons have a square drive which we prefer. :shades:
koihito
Roofing nails meet industry and manufacturer guidelines while being easier and faster to install than any screw :tup1:
dhagin
Those little screws go in pretty fast if they're collated, might be faster than a gun for smaller jobs... maybe. And I think it's fair to say, maybe better than a nail too... maybe. :)
koihito
Dana, there ain't no way in the world you can sink those screws faster than I can drive roofing nails in any size room :yeah:
While I agree that a screw has more grab than a nail, I've torn out enough CBU to know that properly installed a roofing nail has more than enough bite to do the job. The screws are (imho) nothing more than manufactures meeting a demand for an unnecessary product :stirpot:
Levi the Tile Guy
I am with nate. I will occasionally screw 1/2" on the walls, but use my coil nailer for all 1/4", and generally for 1/2" also.
Higher Standard Tile
The screws are (imho) nothing more than manufactures meeting a demand for an unnecessary product
Have you tried using a roofing nailer for hanging cbu on walls over steel studs? I like my roofing nailer for floors also. But for walls I use screws, and a lot of my showers are over steel studs. Plus my 18v Makita impact driver is a lot lighter than my compressor.
I going to thread jack this back to original subject line.:jacked:
Picture one is the picture of the only USG mesh tape that is sold at a local tile store that also sells Durock. It is not drywall tape but Type P for plaster. Is this alkaline resistant or higher quality than drywall mesh tape? It is 2.5" wide.
The second picture is the mesh tape I use for cbu, I get it at HD. It is 2" wide.
Still curious what the USG experts think about using backer on hardi screws for durock as opposed to the rock on cbu screws.
cx
I think the local tile store is confused about their USG products, Isaac. That tape is for use with a gypsum-based plaster and I wouldn't expect it to be of the alkali-resistant class.
But only USG can tell us for certain, eh? :)
Hammy
:jacked: Due drywall being hung on the walls behind my showers. I ALWAYS use screws to prevent wall board damage from hammering on finished walls. Screws are cheap insurance in this case.
Square drive Backer-on screws work best due to phillips head stripping out before completely snugging the BB to the substrate.
Highjack over.
This has been an interesting thread. I add the price of a roll of BB tape to every 6 sheets of backer board when putting my bid/quote together.
Hammy
dhagin
Curious, you nail gun guys...
When nailing down backer boards, how does the changing compressor pressure affect how far the nail is sunk? Is every nail precisely the same height - flush with the top of the board every time? Or do you just crank up the pressure and sink em all? Or do you dial the pressure down and "one time" each with a hammer - like carpenters with shear nailing? Or what? :)
Tiger Mountain Tile Inc
I have the pressure set to flush, or slightly high. I end up hammering 30-50%.
But I only use nails when I can thinset the board down, otherwise I use the square drive screws Issac was talking about.
custombuilt
Ok my thoughts:
Yes nailgun all the time, i go back and hit in maybe 1 out of 20.
I often use the blue 3 inch wide plaster tape. Don't know who makes it, but it is super strong stuff.
Those dinky 50 foot rolls of grey tape should be outlawed. C'mon are all your jobs using 4 sheets of backerboard?
I'm yet yo see a job fail because of improper tape. Lots of them due to a lack of tape....
Jhereg
They also come in 150' rolls, under $10 online
Houston Remodeler
I don't change the pressure to change the nail height, the gun has an adjustment to change the depth the nails are driven.
We just set 15 sheets with a nail gun and had to hand hammer only when the compressor was accidentally unplugged and no one noticed it wasn't running.
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