grout cracking and one tile cracked?

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Old 10-05-11, 02:58 PM
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grout cracking and one tile cracked?

this is addition. framed with boise cascade wood I joists as per plans done by 84 lumber using boise cascade software. not sure deflection? subfloor is 3/4" Advantech T&G with adhesive/nails used to attach to joists. used 1/4" hardibacker attached to subfloor using thin-set and hardibacker screws as per their specs. tape/thin set used over seams. home depot more expensive thin set used to set the tiles(suppossed to allow some flex), the cheaper stuff (but still the polymer kind) used to attach hardibacker. this is upstairs in master bath and laundry room.

laundry-12x12 tiles that i did. used 1/4" notch trowel. the washing machine is on left and dryer on right. right between them running front to back the grout has separated from the tile. the separation is on one side of the grout line and then crosses over the grout to the adjacent tile. no cracked tiles noted.

bath-18x18 tiles that someone else did. 1/2" notch trowel. there is a tile that has crack in it and then crack continues in the grout. this is definitely a tile that you would worry about cracking because it is in doorway that is at 45 degree angle to direction of tiles so tile is cut wierd and has what I would call a weak point susceptable to cracking and that is right where it cracked. note that to the best of my knowledge, I would say that this is probably about mid span (an 18' span of the wood I joists).

any thoughts? the crack is hardly noticeable. wife has not even seen it yet. really don't feel like doing anything right now till see how it progresses. and is there anything I can do to prevent further damage? What should I have done differently? the guy that did bathroom said he has never had a tile crack before and I do believe him. maybe the framing has too much deflection? may try to contact boise cascade and see what the deflection limits of my design are.
 
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Old 10-05-11, 05:14 PM
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framed with boise cascade wood I joists as per plans
What was the planned deflection rating and load spec'd for this floor? Was it know that tiles were to be installed at the time? You didn't mention if these are ceramic or natural stone tiles. I assume it was built to pass building code of course, was it minimum code or what. Code is the worst it can be and still get an occupancy permit.

You said the span is 18', YIKES are you sure? What is the on center spacing of the I-joists? Which model joists do you have?

laundry-12x12 tiles that i did. used 1/4" notch trowel.
That might be a problem. Did you check for min. 85% adhesive transfer after setting a few? 1/4x3/8x1/4 would have been better, plus back-buttering maybe.

Hardie is very thirsty, it's recommended that you damp sponge or mist just before spreading the thin set. Most people don't know or do that.

maybe the framing has too much deflection? may try to contact boise cascade and see what the deflection limits of my design are.
It's either too much deflection and/or a few faults in technique. It wouldn't crack otherwise. Good plan to contact Boise, the retailer and the contractor that built the room.

Jaz
 
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Old 10-05-11, 08:43 PM
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all the tile is porcelain. found info on design. looks like L/480 deflection specified. The joists are Boise Cascade AJS 20, 11 7/8" deep. using their table at L/480, with live load 40, dead load 30 (the highest on the table) , at 16"OC with 23/32 subfloor glued and nailed, these joists can span 19'3". my actual free span is 18'8".

I did check a couple and I would say they were 85%. I did see that I should have back buttered. the bathroom 18x18 tiles were back buttered. but wouldn't using wrong trowel and not back buttering make the tile more likely to crack? I don't have any problems with tile cracking in laundry, it is just grout separating, which would seem like deflection issue?? but isn't my deflection fine based on previous paragraph? that high speed front loading washing machine may put a lot of stress on the floor?

not really worried about laundry room. not expensive tile and small room and not really going to see. I did use grout that has matching grout caulk and can regrout with that stuff in future. big concern is the bathroom. more expensive tile that had to be ordered. I do have extra tile if needed. but want to see what happens when this room starts seeing full usage if I have any more issues before think about fixing it. I also used a grout that has matching grout caulk so can use that. color looks fine and the area is right along the doorway into the toilet room. I thought about cutting out the crack and putting threshold in that doorway. is there any way to make precise cuts in the tile while it is in place? and be able to cut right up to the doorway framing jack studs?
 
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Old 10-06-11, 02:43 PM
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I'm not an engineer but I like to specify at least 50/20 live/dead, 50/30 would be preferred except that the charts I've used don't go higher than 20 on the dead load. I think 40 live is way too low for a tiled floor. However 40/10 is the basic requirement for residential construction when non ceramic floors are to be installed.

Your joists meet code requirements, if they were installed correctly and someone didn't cut any large holes some place.

but wouldn't using wrong trowel and not back buttering make the tile more likely to crack?
That's one of the bad things that could happen. I think first the grout would crack, then the tiles become loose, then break. Have you "tapped" the tiles listening for a hollow sound?

that high speed front loading washing machine may put a lot of stress on the floor?
Very likely, yes. Maybe get a rubber pad or those trays they make for washers.

Jaz
 
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Old 10-06-11, 02:52 PM
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acutally my stupid first plumber did screw up the holes in the joists. after I told him exactly where to cut holes, he started cutting first joist in wrong place! Luckily I caught him after he cut only one. He was going to cut them all this way and after emailing with the engineer at Boise, that joist could not be repaired without a header. Luckily though the cut was right over what was a non weight bearing wall for a closet. I was able to make it weight bearing all the way down to my basement This is at other end of house from where laudry room is located, but that joist does run under laundry room. I don't think the cracking grout is located above that joist.

the cracked tile in bathroom is not near any holes in joists that violated the install instructions. Had one(actually two that were near each other) that I was concerned about but the engineer checked it out and said it was OK.
 
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Old 10-07-11, 07:18 AM
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I-joists I have seen in the past are 19.2" or 24" oc. Are you sure they are 16" oc? I have not seen them 16" oc, but they could be. Whenever I have worked with I-joists I've always added a second layer of plywood due to the oc spacing. A second layer of plywood adds stiffness between the joists, not along their length. I'm rarely comfortable with I-joists because they always seem overspanned and bouncy to me. Like Jaz, I not an engineer either, just talking from my experience.

Washer's and dryers can create alot of excess movement in a floor. Jaz load advice of 50/20 is what I would feel more comfortable with, especially over I-joists with washer and dryer. The 1/4" trowel could be an issue, depending on what the backs of the tiles look like and how flat the floor is. A good rule of thumb on floors is to try to get 100% coverage. Sometimes a larger trowel is required to get 100% coverage. It's also a good idea to burn the backs of the tile with thinet when setting porcelain. Also, what Jaz said about keeping the Hardi damp so it doesnt suck moisture from the thinset.

As to the larger tile in the bathroom, is it just the one tile that has cracked? Look closely, do you see any hairline cracks in the grout anywhere else? Tap the tile with a broomstick. Do any of the tiles sound hollow? Are you saying the tile that cracked has an L cut out of it and that it has cracked from the corner of the L outward? If you lay a straight edge over the cracked tile did one side sink, or are both sides on the same plane? Are you sure the tile wasn't cracked when installed and you didnt notice it right away?
 
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Old 10-07-11, 06:53 PM
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yes, definitely 16" OC. I have the plans, I did all the electric, and I have been my own GC since the house was framed. floor does not seem bouncy to me at all.

I have some pics of cracked tile in bathroom. the crack continues to grout line, then follows grout and on far side of that tile grout also cracked. perfectly flat when lay straight edge across crack. I doubt it was cracked when layed. I usually spot things like this right away.







 
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