Tile Prep Question

ch0mpie

I'm remodeling a kitchen. When I started the ho said she wanted vinyl or laminate on the floor, but now she has changed her mind and wants tile. Half of the kitchen is the original house and the other have is an addition. The room is about 12'x24' The addition had 2x8 floor joises spanning 12' with a layer of 1/2" ply. The original house had 2x8's spanning 12' with a layer of 3/8"ply. I added a layer of 1/2" ply to the whole room, but in the orginal house the floor was wavy and not level plus the addition was about a 1/4" to 3/8" higher than the orignial house. I shimmed the original house floor level before adding 1/2" ply to the whole floor. My floor is sufficient for laminate or vinyl but I'm not sure about tile. I don't what to raise the floor too much higher with a layer of cement board because it is already a 1/2" abovethe floor in the next room. What do you guys think my options are?

Mike Finley

1/4" hardi. I am assuming you have the floor already flex free, I had a hard time following your post. If you really just can't stand that extra 1/4" then look into Ditra.

R&D Tile

I know you don't want to hear this, but, if those 2x8s are are spanning 12' unsupported, they don't meet specs for tile, too much flex in the floor.

ch0mpie

Thanks RD. Without knowing it for sure this was my gut feeling as the floor does seem to have a slight "bounce". I would much rather find out now and deal with it properly than do an incorrect installation and end up paying for it later.

I saw in anther thread you recommended the TCA handbook, I think I'm going to pick one up. Are these kinds of deflection tables included in this reference?

tgeb

Here is a link to a span calculator, Ch0mpie.

http://www.awc.org/calculators/span/...orizontal+Span

I am sure with a search you can find others as well.

__________________
Tom

www.gebcon.com

ch0mpie

thanks tgeb. I checked out a few others too just to cross reference. They all gave me 12' allowable for 2x8's spanning 12', 16oc, 40 live load, 15 dead load. I considered L/360 deflection for ceramic tile. What criteria are you holding the for to RD?

R&D Tile

http://www.johnbridge.com/vbulletin/deflecto.pl

I trust this one, made for by tile guys.


Either way, you already stated it feels bouncy, Yes?, that would be enough for me to beef it up.

tgeb

I would err on the side of caution. Those 2X8s are pretty well maxed out at 12 feet.

I would follow RD's advice. He is the pro in this area. He has helped me through some projects on a different site, never bad advice.

I just happened to have had a link to the span calc you were looking for.

I would consider sistering those 8s, or support from below if possible.

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Tom

www.gebcon.com

R&D Tile

Double-A

While blocking is not effective for 'expanding the span' so to speak, solid blocking will help with deflection.

Will it be enough? Probably not without sistering, but doing both will make it much less bouncy.

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ch0mpie

Thanks again guys. I wasn't questioning RD's advice, I just wanted to know what source he was using. By the book this case may be boarderline, however as I mentioned before the floor is a little bouncy and I don't want any headaches. Fortunately the customer is not dead set on tile and does not want to spend the extra to money for me to sister everything, so we are going to go with a laminate.

On another note, that ditra stuff that Tom recommended looks pretty cool.

R&D Tile

Ditra is a great product, BUT, the floor still has to meet specs to use it.

carl owens

2x8 -16'' Center ?
Remove Ply Install Cement Pads Block An 4x8 Supported Eight Foot Perpendicular Floor Joist.
Stretch String, Check Joist For Flex.
3/4 Ply Floor Rated.
1/4'' Hardie Or Float Mud .
Then Top It Off With Schluter Ditra.
Tile Grout No Call Back .
Hope This Helps .
Carl

Bud Cline

Carl could you repeat that information only this time please do so in english.

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R&D Tile

Carl, no need for Hardie or mud if using Ditra, one or the other.

J DoubleD FLoor

Or you can repeat it in Engrish ... I'm bilingual

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troubleseeker

It has been my experience that ceramic tile and bouncy floors do not mix well for the long term. Beef up the floors and put down a layer of 1/4 inch Durock or hardi backer. Also much better for long term life tha tile glued to wood substrate.

R&D Tile

Glue the tile to what?