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Installing Tile For the First Time - Starting off with Subfloor related questions

Installing Tile For the First Time - Starting off with Subfloor related questions

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  #1  
Old 03-29-06, 11:36 AM
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Installing Tile For the First Time - Starting off with Subfloor related questions

I'm trying to lay ceramic tile in my bathroom. I went to the Home Depot how-to on it, just to see how it was done. However, I don't really think what they said was completely correct, so I figured I'd ask the pros.

I have a 5' x 5' bathroom I want to lay the tile in.

Joist Size: 2x10
Spacing: 16"
Unsupported Span: 12.7'
Current Subfloor: 5/8" plywood (Confirmed by drilling a hole and measuring)

I'd ideally like to keep the increase in floor size to a minimum, however I'm more looking for the best way for a first timer to do it.

What do you recommend for a subfloor - Concrete Backerboard or Ditra or ...?
Will I need to add additional plywood? What grade? Size?
What thinset to use for each? The person at home depot kept pushing this expensive "Mega-Bond" or "flexi-bond" (One of the two) that claims it allows 1/8" of movement.
Every how many feet do I screw my original plywood floor into the joists? And if I add more plywood, does it get screwed into the joists or just the plywood below?


I'm sure I'll have more questions as I get going, but I figure this will be enough to get me started to the point where I can put the subfloor down..



Thanks
Trevor
 
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  #2  
Old 03-29-06, 01:50 PM
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If your floor joists are in good shape (not hacked up by the plumber) they meet minimums for ceramic tile but not natural stone. You say height is an issue but you should at a very minimum add an additional 1/2" of exterior plywood bc or better. The 1/2" plywood should be laid perpendicular to the joists. Stagger the joints so they don't line up on the plywood joints below. Screw the 1/2" plywood to the 5/8" plywood only. Avoid the joists below. Screw every 6" at perimeter and every 8" in the field. Use deck screws (no drywall screws). You can use 1/4" cement backer board or a membrane (like ditra) over the plywood. If using cement backer board, use an unmodified thinset between the plywood and the backer board. Use backerboard screws to secure the backerboard to the plywood every 6" around the perimeter and every 8" in the field. Some backerboards come premarked for screw spacing so you can use their screw patern. Use the backerboard screws with the square drive heads as they are easier to drive home. The phillips heads are a pia to get flush with the board. Using a membrane can save you some height. If you decide to use a membrane, follow the manufacturers instructions carefully.

Screw the original ply to the joists every eight inches or so.

FlexBond and MegaFlex are Customs high end modified thinsets. Versabond is also a good modified thinset and will do the job and is cheeper. Unless you have some reason for the FlexBond or the MegaFlex, VersaBond should be fine. You can use the FlexBond or MegaFlex if you want to spend more money.
 
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Old 03-29-06, 02:50 PM
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DITTO everything above and that is probably the best advice.

I will tell you however that DITRA is a great product and works really well. Your current subfloor is an absolute minimum already. Just so happens that since it is plywood then DITRA is rated for going over 5/8" plywood subfloors and DITRA would obviously minimize the height issues. DITRA could also be used with Versabond which is all you would need unless your tiles are porcelain. If this is the case then use Versabond for installing the DITRA and Custom Blend (unmodified thinset) for installing the porcelain.

Personally.......I would add the plywood as HJ suggests in this case and go his route.
 
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Old 03-29-06, 03:06 PM
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Bud - I haven't looked at the specs for Ditra in a while. My recallection (is that a word) was that the 5/8" plywood had to be t&g, but I'm not sure about that.

TrevorK - Is the 5/8" plywood t&g?
 
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Old 03-29-06, 04:21 PM
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This is true!
 
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Old 03-29-06, 09:54 PM
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Originally Posted by HeresJohnny
Bud - I haven't looked at the specs for Ditra in a while. My recallection (is that a word) was that the 5/8" plywood had to be t&g, but I'm not sure about that.

TrevorK - Is the 5/8" plywood t&g?
I honestly don't know if it's tongue and groove - I was under the impression all tongue in groove meant want that there was a "tongue" piece on one sheet that fit into the "groove" on another sheet.

How do you tell (Without taking the floor up)? When I rip up my lino, would I then see the "tongue" between the sheets of plywood? Would the tongue be on the 4 foot side or the 8 foot side?

EDIT: If it matters, the house is ~30 years old (If that makes a difference in terms of standards)
 

Last edited by TrevorK; 03-30-06 at 08:00 AM.
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Old 03-29-06, 10:15 PM
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Originally Posted by HeresJohnny
Screw every 6" at perimeter and every 8" in the field. Use deck screws (no drywall screws).
Deck screws - would that be the typical "wood screws" you get at Home Depot?

I assume 3" would be the size for the screws that go into the joists, and then 1.5" for the ones that just go into the bottom piece of plywood?

FlexBond and MegaFlex are Customs high end modified thinsets. Versabond is also a good modified thinset and will do the job and is cheeper. Unless you have some reason for the FlexBond or the MegaFlex, VersaBond should be fine. You can use the FlexBond or MegaFlex if you want to spend more money.
From what you said above - if I use cement backer board, then I will need two thinsets, one unmodified between the backerboard and plywood and one modified between the tile and backer board? Do the bags also come with mixing instructions, or do I need to follow the "mix to the consistancy of peanut butter" method?
 
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Old 03-29-06, 10:33 PM
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Originally Posted by Bud Cline
DITTO everything above and that is probably the best advice.

I will tell you however that DITRA is a great product and works really well. Your current subfloor is an absolute minimum already. Just so happens that since it is plywood then DITRA is rated for going over 5/8" plywood subfloors and DITRA would obviously minimize the height issues. DITRA could also be used with Versabond which is all you would need unless your tiles are porcelain. If this is the case then use Versabond for installing the DITRA and Custom Blend (unmodified thinset) for installing the porcelain.

Personally.......I would add the plywood as HJ suggests in this case and go his route.
I've checked the website, and you and HeresJohnny are correct with 5/8" T&G plywood being the bare minimum for Ditra. So you guys would advise even if I had T&G to go with an extra sheet on top correct?

So it's advised that I put 1/2" plywood - what grades are better than BC (Just so I know what type to buy, in case they don't have BC)?

Oh - how is it pronounced (If I have to ask for it) DEEtra or DItra or ?
 

Last edited by TrevorK; 03-30-06 at 08:03 AM.
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Old 03-30-06, 08:17 AM
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BC plywood should be instock, and yes, more ply strengthens the floor, backers or membranes do not. Part of those minimums is a calculated risk of payout on warranty claims vs. the cost of lost market share by having stronger requirements. AC ply would be the next step up, just stay away from anything rated as CDX or "sheathing". CC plugged and sanded is also fine, you'll find that at some lumber yards, but not at a big box.

You might get some blank stares asking for Ditra at a big box store no matter how you pronounce it, but for the record, it's "Dee-tra". You can order it online at www.tileprotection.com and www.tile-experts.com both sell it by the square foot. Big boxes only sell by the roll.

Did that cover it all?
 
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Old 03-30-06, 08:48 AM
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Until just recently my local Home Depot was selling DITRA in the full 300+ square foot rolls only but just recently they have begun stocking DITRA in rolls that have about 64 square feet, if memory serves.

But, back to the plywood option.....in tile substrates, MORE is always better in my opinion.
 
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Old 03-30-06, 12:23 PM
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Just marking for later reference...nothing to add at this time
 
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Old 03-30-06, 10:17 PM
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Originally Posted by Tilebri
Did that cover it all?
Correct me if I'm wrong on what needs to be done.

1) Rip off existing floor to the 5/8" plywood.
2) Put 1/2 BC grade plywood down on top of 5/8" plywood (Does it matter what side goes up?)
3) Put down either
- Cement backerboard with unmodified thinset/screws
- Ditra with modified thinset like Versabond
Is one of the two better for a first timer? Trowel size?
4) Put down tile with modified thinset like Versabond. 1/2" square notch trowel?

Now, when I go to actually put the floor down, the person at Home Depot ran the trowel at an angle, scraping the thinset off the plywood (So that there were patches of wood in between the rows of thinset) - is this correct?

Also - should I bother to backbutter the tile?

And I assume, since my floor is going to raise 3/4" - 1", I will need something to extend my toilet flange. Will this go on after I do my tiling or before?

I think I'm way overthinking this - but I really want to do it right, so I don't have to do it again. Thanks for all your patience with me!
 
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