# Troubleshooting failing tile job



## fcfc (Mar 10, 2012)

I was recently asked to troubleshoot a failing tile job. First off, there is 3/4" 16" oc OSB as subfloor, it has been glued and screwed to the joists. 1/4" cement board with thinset underneath it has been screwed in some places and nailed with what appears to be roofing nails in other places. The tile itself a glazed porcelain 13"x13" thinsetted down with at best a 1/4" x1/4" trowel, no backbuttering. After less than 3 years ~50% of the floor is blown and loose, grout is cracked and in most places the only thing apparently holding the floor together. Joints between sheets of cement board show no evident of taping. Trowel marks below removed tiles show swirl patterns and less than full coverage attempted. Of the several tiles removed, most showed less than 40% contact with thinset, tho some did show almost 100% coverage but were still blown loose. Damage appears to propagate from the area where it is visible below the floor that he switched from screws to roofing nails, tho some areas in the screwed off sections are blown as well. 

While this sounds less than good versus the installer, it is evidenced throughout the rest of the house that there was or is an ongoing moisture issue as their 3/4" hardwood is cupped and moderately blown and squeaky throughout the remainder of their living spaces.

I am questioning if the nature of this failure is actually a responsibility of the installer with his less than 'by the book' installation methods or whatever has occurred with this un-moderated moisture issue causing expansion issues outside normal seasonal expansion. 

I have seen failures happen in many ways, but this one leaves me wondering. Comments are gladly appreciated and welcome at this point.

DW


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## angus242 (Oct 20, 2007)

What is the unsupported span of the joists?

Not taping the seams...
Circular trowel marks...
Not back buttering...
Less than 95% coverage...

Those all contribute. 

We also have no idea of what type of thinset was used or if was mixed properly, slaked or out of date when used.


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## thom (Nov 3, 2006)

What does the thinset look and feel like? Does it appear solid or crumbly? Could the thinset have frozen before fully set? Could the thinset have skinned over prior to setting the tile?

You're correct, a sloppy installation may be the cause but there may be another cause also.


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## cleveman (Dec 28, 2007)

I've laid a lot of tile w/o backbuttering, but I always had a nice floor with 1/2" tilebacker on it, not 1/4". And I always tape the joints.

Durock or similar will cause the mortar to dry out quickly.

Besides that, round up the usual suspects:

old mortar

not enough mortar

mortar applied poorly

mortar mixed poorly

I would like to know what time of year it was done (hot summer)?

You haven't told us the type of joist and span and the type of tile backer.


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## world llc (Dec 9, 2008)

cleveman said:


> I've laid a lot of tile w/o backbuttering, but I always had a nice floor with 1/2" tilebacker on it, not 1/4". And I always tape the joints.
> 
> 
> You haven't told us the type of joist and span and the type of tile backer.


i read on here that 1/4" backer will make the floor feel stronger :whistling


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## fcfc (Mar 10, 2012)

Thin-set for majority of job was supplied by tile supplier, no dates available for manufacturing run on those, but this being one of the larger local suppliers who turns almost 40% of all the tile work in this 4 county area, I am fairly sure it was not sitting on the shelf for too long. Customer did comment that installer did use some of 'his own' supply of thin-set during the install, but could not pin point where.

Cement board appeared to be durock, did not core it to verify at this point, merely scraped off thin-set to see depth of trowel notches.

Thin-set itself was firm and not slumped in revealed trowel pattern, however trowel marks seemed awful low for 1/4"x1/4" combing. Thin-set showed no signs of crumbling or dusting beyond where bond failure had sheered from tile backing. Of the various tiles pulled, almost no thin-set was actually adhered in chunks to the tile itself, (less than 5% overall) And of every tile pulled for inspection, not a single tile was actually broken. From the appearance of the thin0-set beneath each tile pulled, it seems each tile was spread individually, however this was a small cross section considering the size of the floor.

Job was done in summer (this being northern Iowa in new construction without moderated hvac)

Joists were 16" oc with 3/4" osb overlay glued and screwed, entire main level is sitting over a block wall basement comprising the entirety of the main level floor-plan with 8 foot non finished ceiling. Was able to visually confirm the type of fasteners used to attach the cement board by what was showing below. 1.25 inch drywall screws for majority, 1.5" galvanized roofing nails elsewhere.


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## world llc (Dec 9, 2008)

is there a crawlspace under? why is the moisture loading up the floor?


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## fcfc (Mar 10, 2012)

Thats part of my confusion. Its full 8 foot ceiling below all affected flooring, in fact under the entire floorplan with an air exchanger moderated at their preset humidity.

They had mentioned having some type of failure in this module within the first year. But that everything was in full working order, yet on my visit, their wood flooring was visibly and almost entirely cupped, blown, noisy, and frankly shocking to see aside from the tile problems. 

They simply said that that part was another problem, and that is what makes me really wonder aside from poor installation methods what is the underlying cause of such a complete fail. For a 3/4" wood floor to cup across ~3 inch spans with less than 13 foot of total width represents a rather massive moisture issue ongoing or in the past that just doesn't fit the situation. And this being 2 years past the point of repairing the air exchanger. I am puzzled.


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## world llc (Dec 9, 2008)

a long shot, but maybe no insulation at rim between floors and poor housewrap.... warm humid air filling cavity and loading up cool osb?

it sounds too coincidental that both tile and wood are failing.

check for recalls or lawsuits on osb in that area at that time...


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## GO Remodeling (Apr 5, 2005)

thiNGs that come to my mind : 

is this the original owner? could this be foreclosure that was sitting unoccupied, air unconditioned? Flood area?

thinset skimmed over before setting tile.wet or cold tile during install(winter) Tile too hot during install (summer)

upstairs bathroom leak to floor below swelling hardwood and subfloor. Basement took water from failed sump pump.


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## Bonzai (Dec 23, 2009)

Spacing of screws in Durock?
Was the Durock just screwed or was it also glued /thinset?
Was any crack prevention membrane used (OK so I know it's not 'required' but can be a contributing factor)?

The fact that the installer used drywall screws would make me wonder what other corners they cut?!

Sounds like a series of short cuts or lack of knowledge as well as other factors (damp and/or movement) that caused this.


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## PrecisionFloors (Jan 24, 2006)

Sounds to me like the failure is a result of the combination of a less than stellar installation and moisture. One of those deals where a rock solid install would have lived through the harsh environment or a shoddy install would have lived in a perfect environment, but not this particular combo lol. Without seeing it I'd lean towards the poor coverage coupled with probably cheap thinset (who does workmanship like that and cares about the quality of the mud :whistling) being the largest contributing factors.


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## HS345 (Jan 20, 2008)

cleveman said:


> I've laid a lot of tile w/o backbuttering, but I always had a nice floor with 1/2" tilebacker on it, not 1/4". And I always tape the joints.
> 
> Durock or similar will cause the mortar to dry out quickly.
> 
> ...


Cement board adds ZERO structural value to a floor, whether 1/4" or 1/2". This is an indisputable fact.


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## angus242 (Oct 20, 2007)

HS345 said:


> This is an indisputable fact.


Oh, you must have missed that thread here :laughing:

:wallbash:


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## HS345 (Jan 20, 2008)

angus242 said:


> Oh, you must have missed that thread here :laughing:
> 
> :wallbash:


I guess I did. :laughing:

Empirical data doesn't lie.


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## world llc (Dec 9, 2008)

HS345 said:


> I guess I did. :laughing:


post 5 was some of the gas on that fire....


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## angus242 (Oct 20, 2007)

HS345 said:


> I guess I did. :laughing:
> 
> Empirical data doesn't lie.


When you have an hour, a punching bag and perhaps a real good beer....check it out

http://www.contractortalk.com/f73/advantages-hardie-over-ditra-117129/


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## PrecisionFloors (Jan 24, 2006)

angus242 said:


> Oh, you must have missed that thread here :laughing:
> 
> :wallbash:


I thought the same EXACT thing when I saw this thread yesterday...even thought of nearly the same response, emoticons and all. Then I just said "aww  it - it's been beat to death already" :laughing::laughing:


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## mrcharles (Sep 27, 2011)

I usually only backbutter piecework stuff. If I'm laying a floor I go for it. 

The biggest contributers to your issues as far as I can tell are to thin of backboard, Not good enough coverage with the thinset (small trowel, improper technique). I'm sure the mix was off as well.


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## angus242 (Oct 20, 2007)

mrcharles said:


> I usually only backbutter piecework stuff. If I'm laying a floor I go for it.
> 
> The biggest contributers to your issues as far as I can tell are to thin of backboard


TCNA recommends back buttering all porcelain and stone.

1/4" CBU is perfectly fine for a flooring application.


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## PrecisionFloors (Jan 24, 2006)

mrcharles said:


> *I usually only backbutter piecework stuff. If I'm laying a floor I go for it. *
> 
> The biggest contributers to your issues as far as I can tell are to thin of backboard, Not good enough coverage with the thinset (small trowel, improper technique). I'm sure the mix was off as well.


Then you're doing it wrong


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## Groutface (Jan 20, 2011)

PrecisionFloors said:


> Then you're doing it wrong


If you don't know what yer doing...........jester


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## mrcharles (Sep 27, 2011)

Just saw that he said drywall screws.... It's obvious about everything on this install was wrong..... scrap it and start again...... Sounds like you can salvage the tiles:thumbup:


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## angus242 (Oct 20, 2007)

I saw "screws and roofing nails"...


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## andeeznuts (Feb 21, 2008)

Tell the home owner to go on a diet and charge em to lay the floor again.


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