cracked porcelain floor tiles

[Kippee]

The crack has remained unchanged. If the cracked tiles are removed would a liquid or fabric crack isolation membrane be a viable way to correct the problem or is it a bandaid? How effective is this to prevent cracking from any further movement if that is the problem. Has anyone used it? It was suggested to me.

My understanding is Flextherm is replacing FlexSnap with a rolled product in large sheets. Does anyone have any information as to why they are making the change?

[cx]

I see no mention of the joist spacing under your subfloor, Kippee. Do tell what that dimension is.

The crack isolation under only the replaced tiles will be of no real value to you. The manufacturers generally require the isolation membrane be a minimum of three tile widths centered over the crack in the substrate. Here is a drawing of the requirement from one of the best manufacturers of such products.

And that applies only if your problem does not involve the substrate raising on one side of the crack more than on the other. No manufacture of crack isolation products will give you any sort of warranty if such is the case. Their products are to protect against in-plane separation only and I'm not at all sure that's what you're dealing with.

You'd do better to correct the problem at the source, much as you may not like that option.

My opinion; worth price charged.

[Kippee]

Thank you for your response. The joists are silent floor tjI25 16" on center. The room below the bathroom with the cracked tiles is finished, but the basement level, two floors below, has a joist about 75" from the side of the house. The three hairline cracked tiles (48" long crack) is also 75" from the side of the house. Are the joists usually installed in alignment on each floor?

What I still don't understand is why the FlexSnap did not absorb any possible movement the way cement board would. Flextherm states FlexSnap replaces the need for cement board.

Regarding the crack isolation membrane, if we have the 3 1/2 cracked tiles removed would we need to do a 3 x 4 tile removal? The cracked tiles are not raised at all, there is just a long hairline crack running in a straight line through the tiles.

[cx]

Originally Posted by Kippee

Are the joists usually installed in alignment on each floor?

Nope. If they are it's coincidental.

The three by four tiles would be an absolute minimum requirement for use of a crack isolation membrane and would require the middle tile to be centered over the crack.

Seeing no vertical displacement in your cracked tiles does not mean the crack was not caused by vertical displacement in the substrate or subfloor.

My opinion; worth price charged.

[Topspin]

Are the joists usually installed in alignment on each floor?

I may be understanding it wrong, but if what you are measuring where your second floor floor joists are, in comparison to where they are in the basement ceiling, that’s not quite as important. If you want to find out where they are right under your bathroom floor, go to your first floor ceiling and use a stud finder to determine how far it is away from your outside wall.

What I have seen in the past sometimes is right where that crack it is might be a support wall below and the wall above it is offset. Not often seen but when that happens sometimes you will see a crest in your floor where offsetting support walls, for lack of a better term, work against each other. I have that situation in a 2nd floor bedroom where a dining room support wall below has caused a ripple all away across my second-floor room.

Venturing a guess, it’s going to be difficult from our vantage point to tell you just what your problem is, but with additional information from you, we might have some pretty good guesses.

[RipRap]

For grins, lay a 4 foot long straight edge across your crack - is there any crown or sag along that Line? You don't need any displacement if the floor simply bends in that plane due to settling or whatever.

[Kippee]

We heard back from Flextherm. They are only willing to pay for the cost and labor of replacing the four cracked tiles. Should the heating system be damaged, it would be our responsibility. They have not agreed to our request to inspect our floor. After giving them detailed information regarding our home structure and tile installation, they told us they tried to replicate the same problem in their lab but were unable to do so (oddly enough). Yet they state they stand behind their product.

No reputable tiler is willing to replace just the four tiles.

There is a joist that runs beneath the crack, though the crack stopped at 48" and the joist continues another 8'. (It is a 20' TJI joist.) There is no interior support wall beneath the bathroom as there is a large family room below the bathroom.

We are disappointed in the response from Flextherm. Any advice would be greatly appreciated.

[bellabella]

I agree the job should be redone with proper underlayment preparation.
If you can't get the installer to redo the job short of a lawsuit, one idea for an easier less expensive fix is the make a cut on the on or near the crack, break out the strip of cracked tile then replace with a strip of tile leaving a caulked movement joint where the crack occurred. Not ideal but better than just filling the crack with silicone.
Ever better would be to create some sort of mosaic or decorative element over the defect.

[lati_cz]

Years and years ago (one of my first project) , I was converting basement into a family room. I was framing/sheating subfloor, older inspector came to check and told me "not really my business, but I recommend you to keep 1/8" spacing between sheets of plywood and on perimeter". I was installing sheets the way I was taught - as tight as possible. I've never seen single contractor here to keep spacing, all guys pretty much hammer plywoods together... I believe tongue and groove plywoods are designed to keep 1/8" gaping.

When remodel, we re screw all existing subflooring.