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Discussion Starter #1
ok,I'm getting close,almost time to tile the kitchen floor. some questions for you "Jaz". (hope I'm not re-hashing stuff from before)
I assume that one of the first things you ask a prospective customer is "what's beneath this floor"? (that's so you can take your tape measure and measure the "un-supported span" and see if the floor can take tile)
now for the important question: in your experience, have many people just disregarded the news that their floor can't take tile without costly reinforcing and just hired a "less than reputable" contractor to do the floor? (they'll say something like: "baloney,that's not important,I've been doing tile for 30 years and never had a problem"):)
just wondering about that. (not that I myself would disregard any advice from this forum)

tnx,
 

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Tileguy
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Hello again,

Wow, asking for me personally huh? This time you might receive an invoice. :laughing:

Luckily just about every home I have worked in met the min. building code of L360 deflection which is also the min. spec for ceramic tiles. A few were so bad that I gave my opinion and walked away.

Some people think the truth for proper tile installation is achieved through democracy. If 3 people say it's fine and one says it doesn't meet specs, they're likely to believe the 3 hacks. Pricing is the same. After a failure, when asked about the handyman they hired, they say they did not hire the cheapest. Well ok, but they only searched out people that weren't qualified and therefore all the prices they received were too low, and they got what they paid for.

Your quote;
"baloney,that's not important,I've been doing tile for 30 years and never had a problem"
is something we hear often here on these forums.

That's why it's best to edumicate people about how it's supposed to be done. A cynical person will dismiss good advice, thinking that he's only trying to charge more and the other guy has been in the business a long time and so he must know what he's doing. Yea right. :whistling2:

Jaz
 

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Discussion Starter #3
good to see you're still around "Jaz":)

anyway,been meaning to ask about "Ditra". It sure looks like a good product, especiallly compared to the alternative which the manufacturer says is just as good but cheaper. (It doesn't look like it even compares) yes,it IS more expensive than CBU but it seems to be worth it. question: would using "Ditra" on a floor that fails the "flex" calculations by not a whole lot, actually negate the calculation? it sounds like it MIGHT,after all, using "Ditra" actually allows the tile structure to "float" over the substrate and any movement of that substrate wouldn't be transferred to the tile. is this just crazy thinking?

ps: I've still got those 3 bags of special "thinset" that I bought at "Bedrosians" awhile back which is supposed to "negate" the calculations. (to a certain point anyway) maybe using that thinset AND Ditra will "super negate" the calculations.:)

tnx,

oh yes,Jaz,glad the building department hasn't caught up with you yet, we still need you in this forum.:jester:
 

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Tileguy
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Schluter makes no claim that Ditra should be installed over a floor that does not meet standard deflection specs. Ditra helps more by uncoupling the tilework from the substrate, therefore for lateral movement, not deflection.

Ditra costs me a little under 2x the cost of CBU's, but it's easier and much better. If I had to pay retail, I might think twice, well for sure I would.

That super thinset is Reflex by Hydroment, real good stuff but it's modified so use it to install Ditra, not the tiles if you wanna follow Schulter's wishes. I might forego the warranty and use it for the tiles anyway. Just give it an extra day to dry before grouting. The first choice would be to bring the floor structure in compliance though.

Oh yes, the building departments don't much care about how the tilework is done.

Jaz
 

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Discussion Starter #5
ok,so how would one go about strengthening the floor to get it into spec.? should I "sister" 2x10's onto the existing ones or put a "lally column" right in the middle of the floor to support the floor above? (that approach would not be ideal since the pool table would have to go)

tnx,

oh yeah,musta confused you with someone else who ran afoul of the building dept. after all, "jazman" IS a pretty common handle.:)
 

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What's under this room? And what is the unsupported span and dimensions of the current floor joists. Also, do you know the species (you may be able to find a stamp somewhere on the joists)

Sister lumber to the existing floor joists, with construction adhesive and screws. When I did mine, I just sistered the length of the room, not the entire joist length. I attached 2x6's to the existing 2x10's. I'm sure one of the pro's will have a recommendation for you, when they know more about your current joists.

If this room is above a crawl space, you're lucky. Otherwise, you'll have to either cut out the subfloor or open up a ceiling.
 

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Discussion Starter #7
hmm...just looking at the calculations from "John Bridge" a bit more closely this time and I see that my floor only misses the spec. of L/360 for tile by a rather small amount. from what I can tell, L/360 means a deflection of 1" in a 30 foot span is ok. well that means a deflection of 1/2 in. in 15 ft. is ok. my span is 15 ft. and my deflection comes out to .566 in. my question is: "is there any tolerance in the calculations or are they set in stone?

tnx,
 

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Tileguy
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Ken,

I think your joists rating is about L318, which is risking it for the books. But depending on the condition of the joists, their species and grade and the type of load the floor will receive, it may still be alright. Obviously you should try to stiffen them up if at all possible.

There is no magic that happens with these specs. It's not gonna be guaranteed to work at L360 and better, or fail at L359. These numbers are to guide you to determine where you stand. Plus you've got Reflex mortar.

For the record, the deflection along the joists' length is more forgiving than the deflection between the joists. (subfloor strength). The difference is curvature of the subfloor is greater as the distance is reduced.

I noticed you posted at JB's the other day. Good move too.

Jaz
 

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Discussion Starter #9
even with that "reflex" mortar, I'll have to give serious consideration to stiffening the floor. woudn't be easy since the room down there is finished. (and a big ol' pool table sits right in the middle)

tnx,
 

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Discussion Starter #10
maybe instead of "strengthening" the floor for tile, I'll go the "coward's way" and put down some wood flooring (or something fake that looks like wood) :) sure be alot easier! what do you think about that "Jaz"? or are you a dedicated tile guy at all costs?:yes: is there much of a cost differential between having tile put down vs wood?

tnx,
 

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Tileguy
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Wood is nice for kitchens too. All depends on your household and habits. Expect more maintenance and plan to refinish every 5-10 years if you don't like dull traffic patterns. Go barefoot and it'll be good for a long time as long as it doesn't get wet.

"Or something that looks like wood". Oh no, don't do that! You mean like laminate?

Jaz
 

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Discussion Starter #12
Wood is nice for kitchens too. All depends on your household and habits. Expect more maintenance and plan to refinish every 5-10 years if you don't like dull traffic patterns. Go barefoot and it'll be good for a long time as long as it doesn't get wet.

"Or something that looks like wood". Oh no, don't do that! You mean like laminate?

Jaz
so,I guess you're saying that you don't care much for laminate. even the "high end" stuff? the advantages seem to outweigh any disadvantages. even LOOKS like wood! (one drawback is that it won't add to the value of the house,but hey,my "assistant" and I are going to live here t'ill we "croak",and after THAT,who cares?):thumbup:

tnx,

tnx,
 

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Tileguy
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OK, that's fine. Just remember that laminate is equal or perhaps a slight upgrade from vinyl.

Laminate are popular because they're fairly inexpensive and can look kinda real. (if the lights are off):laughing:

Many people can't stand to noisy hollow sound when walking on them. All depends on what you're looking for quality wise.

Jaz
 

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Congoleum AirStep Just had it done on my kitchen floor. Its looks great. They recommended going over existing plywood with 1/4 inch smooth plywood for best result. I authorized it. I couldn't believe how easy it was for them to put down. Definitely diy friendly. Or take a chance on the tile. Hopefully it won't crack do to flex. Mine is a tile pattern. Sounds like jaz thinks your rolling the dice. There are several application for installation. Full adhesive. Perimeter adhesive. Or a special double stick tape on perimeter. I think the tape is like 26 dollars a roll.
 

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Discussion Starter #15
OK, that's fine. Just remember that laminate is equal or perhaps a slight upgrade from vinyl.

Laminate are popular because they're fairly inexpensive and can look kinda real. (if the lights are off):laughing:

Many people can't stand to noisy hollow sound when walking on them. All depends on what you're looking for quality wise.

Jaz
well, tile would definitely be better qualitywise, but I'm just nervous about putting tile down after "flunking" the flex test. yes, I COULD strengthen the floor BUT that would be a hassle. (expensive too. being disabled, I'd have to hire somebody,there's a limit as to what I can do now)

tnx,
 

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Tileguy
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If there's too much month left at the end of your money, you know what to do. It's all about priorities. There isn't that much difference in cost between the options if you're doing the installation yourself. If you're not able, different story.

Frankly I think if the small deflection deficit was only from the joists, (as yours), I would be inclined to go for it anyway knowing the charts are very conservative and with a little overkill built in. My answer would be different if the deflection between the joists was too high. Different dynamics in the latter.

Jaz
 

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Discussion Starter #17
ok,on to something else: (not sure if I should start another topic :) but...
I've got this "powder room" I'm redoing. (yes Jaz,tile will be going down!) anyway,I'm removing the vinyl flooring and find that underneath is a 1/4 in. underlayment of what looks like "luan". should I leave it and put "Ditra" over it or remove it and put the Ditra right on the 3/4 plywood? or maybe remove it and replace it with 1/4 plywood?

tnx,
 

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Tileguy
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You must remove the luan, then re-screw the subfloor and install either 1/4" concrete board or Ditra. No 1/4" ply allowed in a tile installation. How's the joists deflection in that part of the house?

Jaz
 

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Discussion Starter #19
You must remove the luan, then re-screw the subfloor and install either 1/4" concrete board or Ditra. No 1/4" ply allowed in a tile installation. How's the joists deflection in that part of the house?

Jaz
by "re-screw the subfloor " do you mean, to get the squeaks out? I was going to do that anyway.
the luan is stapled down so it shouldn't be too hard to remove.
I ran the numbers and deflection is ok.

tnx,
 

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Tileguy
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OK then. If the numbers are good, looks good, and feels good, then I guess you're good!:thumbup:

But yes you always re-fasten the subfloor even if there's no squeaks. Today no squeaks, in a few months it all changes.

Jaz
 
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