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House_Amuck 03-18-2007 10:11 AM

Backerboard not in mortar -- How bad is that?
We are having our bathroom redone and I'm starting to notice things the contractor does that don't match "good practices"--admittedly, as I understand them from reading a lot on forums like this one. One of the things I noticed is that the cement backerboard on the floor is just screwed directly onto the plywood subfloor and I see not sign of mortar near the edges, etc, that would indicate that these had been set in mortar. I thought this was how it was supposed to be done, or is this a matter of opinion?

Now that they haven't done this (and the drywall and beadboard and baseboards are all down and the next step is the tile guy coming in to do his thing--redoing it looks like would be difficult) what are the consequences? Does it lesson the life of the tile floor or..? I don't want to make it an issue since I'm already having them pull out a steel tub they installed improperly (didn't set it in mortar.) It's a "choose your battles" sort of thing.

Oh, the tiles that will be put down are these American Olean black and white 20s era style tiles:

Any feedback?


AtlanticWBConst. 03-18-2007 10:32 AM

General practice is to use thinset.

Maybe he used a different kind of adhesive like Liquid nail?

Whatever the case, 'Durock' installation directions say to use thinset for their flooring installation process:

it's on page 10 of 12:

Here is another intersting article:

House_Amuck 03-18-2007 11:10 AM

Thanks for the links!

I really am not able to see anything that leads me to believe there is thinset beneath the boards. He did screw the backer boards into the plywood subfloor with what looks like deck screws (have square insets in heads).

What I'm wondering though is, since I've already had one head to head with this contractor about resetting the tub--what are the consequences of saying nothing and just letting this one go by? Will my tiles crack and buckle as the durock shifts over time? I rationalize to myself that the smaller tile we are putting in would weather shifts better than a larger tile would, but I'm still a bit concerned. If there are some people that do it the way he is doing it and most of the time it's fine, then I'm inclined to not raise my blood pressure again by butting heads with this contractor.

jproffer 03-18-2007 11:36 AM

Liquid Nails is not for use under durock. It remains flexible (somewhat) after it is dry. There should be thinset under the durock everywhere...if there's not make him take it up and do it's YOUR home he's working's YOUR money that's going to be wasted if he doesn't have thinset under the backer. It will flex into any imperfections in the subfloor. The purpose of the thinset is to hold the durock UP, the screws hold it down. Non-mod thinset is what to use. It won't stick (as much) to the subfloor below and will allow the rock to expand and contract at it's own rate, which is what keeps the grout from cracking. The lack of thinset will also void ALL warranties on the entire floor. Even the lack of thinset under one sheet, or even a partial sheet will void the warranty on the entire floor. Similar to a warranty on roofing, they will look for ANY reason to not pay it...on your roof, one nail out of shingle misplaced...voids the whole roof.

Make him do it right, or not at all.

EDIT: Also, since he's taking it up anyway, and it won't cause any more work:)...when he puts it back...he should use the screws made for Durock, not deck screws.

Darylh 03-18-2007 11:44 AM

Find out exactly what product he used for the cement board, then go to the manufactures web site and down load the installation sheet and if it says to use thinest print a copy, then ask your contractor if he used thinest and if he says "no not necessary ask him why and then pull out the installation sheet and see how he reacts. One big thing to remember is a Contractor must obey the Manufactures installation directions or the Warranty will be void.

JJC 03-18-2007 11:50 AM

What Darylh said. It is important to have all the "ammo" before you confront the contractor.

JazMan 03-18-2007 12:11 PM

Hi J,

It's not a matter of opinion like vanilla or chocolate. All tile backerboards MUST be set into thinset mortar if you want the job to last like it's supposed to. As mentioned above its purpose is not to keep it from shifting side to side, but to support it so that it doesn't move up and down. No amount of fasteners will stop that movement if there is no thinset under to support. No backerboard has grain, non add structural strength. The board will eventually move a hair and will crumble around the fastner.

It is not likely that this will cause tiles to crack, but I guarantee some grout cracks in 2-5 years.

Obviously the contractor does not know as much as he should if he's going to take people"s money for his labor. I wonder what else he might not be doing right?


AtlanticWBConst. 03-18-2007 01:10 PM


Originally Posted by jproffer (Post 37415)
EDIT: Also, since he's taking it up anyway, and it won't cause any more work:)...when he puts it back...he should use the screws made for Durock, not deck screws.


AtlanticWBConst. 03-18-2007 01:15 PM


Originally Posted by JazMan (Post 37425)
Hi J,
Obviously the contractor does not know as much as he should if he's going to take people"s money for his labor. I wonder what else he might not be doing right?

That's what I was thinking in regards to the tub issue the poster mentioned too.

That's the most pathetic thing to alleged 'contractor'.... that has to be told by the homeowner to fix their substandard work .... or have to be told by the homeowner how to properly install something :icon_rolleyes:

They should get into another line of work... (Grocery stores are always looking for more baggers)

House_Amuck 03-18-2007 09:01 PM

Images of Cement Board -- Feedback?
So many helpful comments...thanks so much!

I can't figure out what kind of cement board this is. I looked on the web and Durock says "Durock" on it and it's not Hardibacker. Those are the only brand names I know. This board is not imprinted with anything (generic cement board?) Also, could someone tell me what type screws these are? They don't look like Durock screws (but if the product isn't Durock, maybe that doesn't matter.) I did see a cement board screw that had a square indentation in the head, but some deck screws take square bits too, don't they?

Shouldn't I be able to see thinset along the edges and between the boards? All I'm seeing is bare plywood. I'm still getting an ulcer deciding whether to confront this guy or not. Some of the board extends under some installed things, like baseboards and, worse, a kneewall. Pulling it out would be a PITA and since they are already squawking about tearing out and resetting the tub, this could get ugly and I'm not sure I'm up for it. Of course I want the job done right, too. Very frustrating. And to think we interviewed 8 contractors and chose this one! (Grass is always greener...)

If you click on these it will take you to the webshots account I created for this and other pictures of the bath are also included. (Since I'm discussing the improperly set tub on another forum.)

jproffer 03-19-2007 12:52 AM much to say, here we go:

picture 1...there should not be that big of gaps between the durock and the wall (not Durock brand, but that's what it is BTW. The fiber imbedded rock is what I call durock).

picture 2...the sheets used were broken before they were installed I would assume. They should have been saved for cuts and small pieces. Those "holes" will fill with thinset, which is perfectly fine (if they'll do it), but it's evidence of a hack job. I'd be more concerned with the "what else" factor. I don't see any thinset under what I can see. The mesh is kinda in the way, but I don't think there is. You would see it between the sheets if there's a gap. It would look kinda like a comb effect. A 1/4" of thinset, a 1/4" of nothing (or very little thinset), a 1/4" of thinset, a 1/4" of nothing..and so on.

picture pretty well ok for the 10" that I can see. Except for the screws...wrong screws. BTW, this is what you're looking for. I'm in no way promoting that was the first one out of 16,200 on google for "durock screws".

I wouldn't get worked up over it at all. He knew (or should have) that it had to be done right...if he doesn't know what that means he shouldn't have bid the job. Don't beat around the bush....just tell it flat out.. "Take that up and do it right, I don't care what it it right, or I'll find someone else who will."

If he agrees to that pretty easily, let him off the hook for under the knee wall. He can just cut around it. Noone will be walking under the wall anyway:jester: ...but don't let it go too easily. If he tries to play hardball, then respond in kind.

As far as the baseboard, chances are there's no screws under there anyway so it will slide out when it's unfastened.

beer_geek 03-19-2007 07:02 AM

I can't really tell from the pictures because I need to see more of the sheet. Anyway, IIRC from the last tile job I did, Durock has a rough side and a smooth side. The Durock logo is on the rough side and that's the side that should be facing up. Like I said, it's tough to tell but it looks to me like that has been installed with the smooth side up. Do the sheets look to be the same texture all the way around? If the rough side is up, you can see a transition from the rounded edge for a couple of inches. It would be where you'd tape it. That's kinda smooth, then the field is rough. If if all looks the same, it could be upside down.

Per the durock website:
Board is smooth on one side for adhesive applications, textured on the other for thin-set mortar applications.

Is he going to use thinset?

I hope I'm explaining myself properly.

House_Amuck 03-19-2007 08:20 AM

No Thinset
Tile guy says that this contractor never uses thinset--that it's not necessary over plywood that is nailed into the floor studs--that if it were a planked subfloor that might be different. That the contractor uses adhesive. When I said this is not industry standard he just shrugged his shoulders and said "I've been tiling over it done that way for 20 years and I've never had a problem." What can you do when you are up against that, really?

I need to start a thread somewhere else about the tub they set improperly. they are pulling it out now. This is such a nightmare.

I'm hoping that the durock isn't upside down, that it just isn't durock but a generic unprinted thing. I hope so.

It's awful but you get to the point where you just want them out of your house, no matter what.

beer_geek 03-19-2007 08:26 AM

If he's using adhesive, then it is right. The smooth is for adhesive, the textured is for thinset.

JazMan 03-19-2007 10:00 AM

House Amuck,

I sent you a PM, call me if you want.


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