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tilenovice
03-10-2005, 08:16 AM
I thought I had it all figured out. I have two areas I am tiling, the kitchen and foyer. The kitchen had 7" joists with a 12' span, 16" on center. This provides a deflection of L/210. I was going to sister the joists with 2x8 10', just doing the middle section, which would increase the deflection to L/421.

The foyer has a 15' span, 7" joists, 16" on center for a deflection of L/115. There is an intermediate support which I ignored because it does not look like it gives good support and is also cover by duct work and I can't see it fully. I was going to add a new load bearing support wall next to the heater so the spans would reduce to 8' and 7' for deflection of L/780 and L/577. I was just planning on a 2x6 double header, supported by 2x4's every 16". The base would be installed on the basement floor. It is only 4' to 4'6" wide.

The problem is I read in the archives that large ceramic/porcelain tiles should be treated like stone and have a deflection of L/720. I am using 16x16 tiles, what should I do? I bought the tile last night. I can probably return for 12x12 tiles but will probably pay a restocking charge and the wife and I like the look of the large tiles.

FYI - The existing subfloor is 3/4" T&G planking which I will add 1/2" plywood and 1/4" Cement backer.

Thanks,

Tim

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bbcamp
03-10-2005, 09:20 AM
Tim, a while back ther was a self-perpetuating rumour that said you needed L/720 for large format tiles. That's not true. There is no requirement from the TCA or anyone else like that. What you are doing is fine.

tilenovice
03-10-2005, 09:34 AM
Bob,

Thanks for the quick reply. I was hoping that was the response because I did not want to return the tiles. They are pretty heavy.

John Bridge
03-10-2005, 08:11 PM
Tim,

Bob started the self-perpetuating rumor. He claims I did, but that's not true. :D

tilenovice
03-10-2005, 08:21 PM
What is the best glue for sistering joists? I was planning on using liquid nails, Is this good or is there something better? I am sistering a 10' - 2x8 to a 12' span with 7" joists so I am just sistering the middle section.

I know I saw it in here somewhere but can not find it.

Tim

Rhode Island Flooring
03-10-2005, 08:27 PM
Yes I personally say liquid nails is good, and I screw the sisters to the main joist, (dont sound good) some may say bolts and I may be corrected. as somone posted make sure the crown of the sister/2x4 if facing up.

Mike2
03-10-2005, 08:33 PM
Hi Tim.

I imagine most framers will have their favorite for this situation...mine would be PL 400 polyurethane construction adhesive. I'd also through-bolt (min. 1/2" galv.) that sister, every 24", staggered.

cx
03-10-2005, 10:20 PM
I've 'splained my sistering preferences a number of times over the years. Here's one (http://www.johnbridge.com/vbulletin/showthread.php?p=155737&highlight=sistering#post155737) place. Look at post #36.

My preference in glue if all the wood is clean and relatively flat is Titebond II wood glue in a full spread. You can also use construction adhesive such as Liquid Nail or Mike's favorite, PL-400, or similar. Whatever you use, you gotta be fast, so you gotta plan your installation well and have everything ready before you apply glue.

My opinion; worth price charged.

mrjetskey
03-11-2005, 08:40 AM
Since this is your first time laying 16" tiles there is a few things that really need to be almost perfect for a good job.The floor must be very level(larger tiles span across imperfections and are harder to keep level unless floor is real close)Take extra care ensuring a full bond,using correct trowel and rake thinset evenly,And use a longer level that at least is 48" long ,you won't regret it! Basically I am just trying to say it is harder to set 16" than 12" for us newbies but you made the right move coming here and asking the pros (NOT ME) questions.I wish I had.Since my first 2 were 12" jobs came out great.I didnt take extra time to check up on laying larger tiles resulting in my having to pull a few I wasnt happy with.Just take extra care in leveling them and getting sufficent mortar below. HAVE A GREAT DAY!!!!

tilenovice
03-20-2005, 08:53 PM
I am about ready for the CBU install. I have read a lot of information in this forum but need to verify some things.

1. Spacing should be 1/8" between CBU sheets and 1/4" at walls?

2. 1/4" x 1/4" trowel for unmodified thinset below?

3. Screws every 6" on ends and 8" in center area?

4. Biggest confusion - Taping and thinset. I think I read here that you should fill seams with thinset, put on tape and cover tape with thinset smooth. Let dry overnight? Then I read you can tile over CBU right after CBU install. How can this be accomplish if the thinset in the seams must dry? Can you thinset seams, cover with tape and then put tile over before thseam thinset drys? Is either way better or worse? I need to ship the wife and kids out of the house the day I tile because I am tiling the foyer and kitchen and can not have traffic on the floor. So timing is critical.

5. Also, what do you do at the CBU edge at the wall, any tape or thinset or just fill when tiling without tape?

I guess that is it for CBU install.

Thanks,

Tim

Raymond S
03-20-2005, 09:26 PM
Hi Tim,
Let's see-
1. Yep
2. Yep
3. Check with particular cbu maufacturer
4. You can do it either way, but if you tape as you tile you won't have those unsightly bulges or bumps to sand or rub down.
5. Not sure i follow your question, but you don't want to fill in the 1/4" gap between the cbu and the wall, leave it open for expansion.

cx
03-20-2005, 09:27 PM
Please keep all your questions about this project on this thread, Tim. Helps prevent confusion and duplication of questions and answers. For example, the very first post on your new thread would be someone axin' about your joist structure. Keep it all here and everyone can keep up with the history. :)

What Raymond said.

I need to ship the wife and kids out of the house the day I tile because I am tiling the foyer and kitchen and can not have traffic on the floor. So timing is critical. Good lord, man, don't look no gift horse inna mouth! Ship them off for a week. Tell'em that's how long it takes. We'll back you up. :D

tilenovice
03-20-2005, 09:48 PM
So the tile also stops a 1/4" from wall. I should leave the space between the CBU and wall empty for expansion. Also, I guess you should not put grout between tile and wall. If this is correct, what about tiling up to an existing toe kick under my kitchen counter. Should the toe kick be removed, cut and reinstalled after the new tile? (Great, more work.)

OK, CX, please forward me an email detailing how the tile project will take a week and I will let my wife know. (LOL)

Tim

cx
03-21-2005, 12:21 AM
I'd remove the toe kick trim board if there is one. Easy enough to make another. If there is no removable trim, just stay at least an eight of an inch away from the kick and install a trim piece when you're done.

My opinion; worth price charged.



Not to worry. We can buy a week just waiting for the grout to be dry enough to apply sealer. We can get you all the time you need. :D

tilenovice
03-21-2005, 10:23 PM
Quick recap - 3/4" T&G, I will cover with 1/2" plywood type BC and 1/4" CBU. There are a few holes in the 3/4" T&G, max diameter of 1.5". Should I fill the holes before I lay the 1/2" plywood or are the holes no big deal. If I should fill, with what?

Thanks,

Tim

tilenovice
03-21-2005, 10:26 PM
CX,

I tried to keep a continuos thread for my project but I wanted to ask about a different subject and the title thread did not change. How can I change the title thread when I want to switch subjects?

Tim

tilenovice
03-23-2005, 07:37 AM
Tried to continue existing thread but could not change thread title so I did not get any replies.

Quick recap - Already re-supoorted floor by sistering joists in one area and cutting span in another. Have 3/4" T&G, I will cover with 1/2" plywood type BC and 1/4" CBU with unmodified thinset both screwed.

I am going to start to lay plywood on Friday. There are a few holes in the 3/4" T&G, max diameter of 1.5". Should I fill the holes before I lay the 1/2" plywood or are the holes no big deal. If I should fill, with what?

Tim

muskymike
03-23-2005, 08:07 AM
Hi Tim, if the holes are only 1 1/2 I wouldn't worry about it if you are going over it with ply.

cx
03-23-2005, 08:22 AM
You can't change the title on your thread except soon after you've started it, Tim. You can PM any moderator to change it for you if that becomes necessary, but usually it isn't. If you don't get an answer to a question on a thread, just make another post to it and bump it up to the top of the queue. Starting new threads, although it might get you some initial attention, will almost always result in confusion and duplication of posts. Just stay with your thread and add your questions. Sometimes it gets very busy hereabouts and the moderators and our other frequent contributors have a little trouble keeping up. :)

Now, as to your question: What Mike said.

tilenovice
03-30-2005, 07:00 AM
Been a while since my last post so I could not continue my thread. I already resupported floor, and laid 1/2" plywood on top of 3/4" T&G subfloor. I will be laying the cement board this weekend.

1. I purchased Wonderboard cement backer and it states to use modified thinset under the board. From what I have read on this site, unmodified thiset is recommended. Is there a difference? Which is better to lay cement board? Should I use the modified as stated in the installation directions?

2. Is there special tape for the CBU seams or is it just the fiberglass mesh tape? I did not see special tape at HD but I also did not ask. That had regular fiberglass mesh tape next to the Cement board.

3. I will be laying 16x16 tiles. An old tile guy my Dad knows said to use a 1/4"x1/4" trowel. Trowel the floor and also back butter the tile with the 1/4"x1/4" trowel because of the size of the tiles. Does this sound correct?

4. Last questions. Can not walk on tile for 24 hours after install, correct? Also, 24 hours after grout install, correct?

Thanks,

Tim

bbcamp
03-30-2005, 07:26 AM
Welcome back, Tim.

1) Always follow the manufac turer's instructions, espcially if you want them to honor their warrenty. That being said, we do not believe the bedding thinset needs to be modified, it simply fills the voids between the backerboard and the subfloor. Bonding strength is not an issue.

2) The fiberglass tape next to the backerboard is probably the right stuff, but read the lable to be sure. You do need to tape the joints.

3) Tiles that big may need a bigger notch, depending on the flatness of the back of the tile and the floor. The technique you describe is about right (backbutter with the flat side of the trowel). The best way to be sure is to set a few tiles and pull them back off to check the coverage. If you are not getting 100% coverage, you need more notch.

4) If those are porcelain tiles and you are using a modified thinset, giving them an extra day won't hurt a thing. Modified thinset needs to dry as well as cure, and porcelain does not absorb water very well. 24 hours after grouting is fine, but check the bag for the manufacturer's instructions.

cx
03-30-2005, 08:15 AM
Tim, my son, it's never too late to continue a thread. Just bookmark the url and you'll be able to find it again no matter how long from now. Just make your post and it pops up to the top of the queue, even if it's got mold and barnacles on it. :)

1. What Bob said about the instructions. Different CBU manufacturers have different requirements. If you want them to warranty your installation (which Custom will do) (http://www.custombuildingproducts.com/ResourceLibrary/HomeownerWarranties.aspx?user=pro&lang=en), you must use their products and their installation methods.

2. Same as #1. I think you'll find that Custom doesn't even require you to tape the joints on Wonderboard.

I've got some differing opinions on how some of that stuff aughta be done, but I ain't offerin' no warranty, neither. I suggest you do just what they say and use just what products they recommend. :shades:

My opinion; worth price charged.

tilenovice
03-30-2005, 09:25 AM
3) Tiles that big may need a bigger notch, depending on the flatness of the back of the tile and the floor. The technique you describe is about right (backbutter with the flat side of the trowel). The best way to be sure is to set a few tiles and pull them back off to check the coverage. If you are not getting 100% coverage, you need more notch.


4) If those are porcelain tiles and you are using a modified thinset, giving them an extra day won't hurt a thing. Modified thinset needs to dry as well as cure, and porcelain does not absorb water very well. 24 hours after grouting is fine, but check the bag for the manufacturer's instructions.


How thick should I backbutter? How do I keep even coverage. I was going to use the notched side of the trowel to backbutter so I would have even coverage.

It is porcelain. Is it OK if I only wait 24 hours. Might I cause any problems? I am laying the tile on Saturday, starting early. I really need to grout on Sunday so the house can be usable for Monday night. The house is unusable when you can not walk on the tiled area and I am shipping the wife and kids away all weekend. The only other option would be to grout the following weekend but I really want to complete this weekend.

Tim

Mike2
03-30-2005, 10:04 AM
Tim, when you backbutter the tiles you are "burning" in only a thin layer of thinset using the flat side of the trowel. Use the notched side on the floor/CBU.

Re. your timeline this weekend: Since we don't know how many sq. ft. are involved with your kitchen and foyer, I'll just say you may not be able to complete all the tiling in one day (Saturday). It might even take two or three days depending upon chosen pattern, border, and number of cuts. Note that even after 24 hours, the thinset is still somewhat soft and while it may support very light traffic, you might want to get some small pieces of plywood to kneel on while grouting. Any movement of tile, which may occur during this early cure stage of the thinset, will result in a permanent bond failure.

tilenovice
04-05-2005, 11:53 AM
The project is almost complete and wanted to thank everyone for their help.

I laid the cement board on Friday night after work by myself. That was a long night. The project size is about 200sq ft.

I laid the tile on Saturday with help from my Dad and his new tile saw. He cut and I laid the tile. Cutting the 7/16" porcelain was not easy. That took the entire day; into the late night hours. I did not walk on the tile for at least 48 hours just to be sure.

Now the last step is to grout. Any tips for grouting? I installed 16x16 tiles with 3/16" spacing. My tile has the rough, jaded type edges. Does this change anything in the grouting process? I hear this is the easy part of the tile project.

Tim