Isntalling porcelain tile on top of porcelain tile advice

[cdmariscal]

Hello Everyone

I have a question i'm hoping you all can help me with. i have a large
terrace/pool area which is about 2000 sf. right now, i have about 20
year old porcelain tile on there. it was well put and it has not
cracked but it's just old and ugly. we've tried cleaning it and
sealing it, but it's just really ugly, old and grey. so we've been
shopping around the last few months and found a great deal on about
2500 sf of new outdoor non-slip 18x18 porcelain tile. so now my issue
is, how to install? i've had about 5 installers come out and everyone
gives me a different opinion:


1) first guy said he's lay it right on top of the current tile w
"multi bond" and it would be just fine.
2) guy # 2 said we had to pull out all of the old tile that is there
now bc the new tile will just come off in a few months or in a year if
you lay it right on top of what is there. he says there is no way
porcelain tile will absorb any thin set or bonding and that it will
just start coming off, especially since it's outside and with the
change in weather. i live in north florida, and it gets really hot,
and in the winter it gets cold.
3) guy #3 said he would simple scratch it up with some tool so that it
will absorb. no need to pull it all off. it's hard messy job to pull
everything out and they want to do that just to charge more. he just
scratches the bottom tile up really good and puts plenty of bonding
and thin set on it and it should last another 20 years.
4) 4th guy said he uses this special new material called "PORCELAIN
SET" and it the best. it's $14 a bag but this stuff will bond
porcelain better than anything else, no need to scratch anything.
before you think he wants to scam me, he doesn't sell it. they
actually sell it in the store where i bought the tile. he says most
folks just want to buy the regular multibond product they sell in home
depot that's $6 a bag. but he says that he's noticed that this
particular product that they sell in the specialty floor stores works
really well.
5) last guy said the PORCELAIN SET stuff is just an excuse for you to
pay more $ for bonding. he insists that regular multipurpose thin set
and bonding will be just fine. he says it all depends on what is
there now. since what is there now is in good shape and is not
cracking or coming up, then laying new tile on top should be no
problem. If we scratch it up and put in regular thin set and bonding,
we should be just fine for at least another 12-14 years.


So you see, i've gotten a different story from everyone. they all add
on another $1 a foot for pulling it out and charge about $1.75 to $2
to install it. so if i can save 2K and not have to pull it out, that
would be the best. i'm 5 months pregnant, so this isn't the kind of
job i can do myself right now. i need to find a good contractor at a
decent price. i just want to know what you all think is the safest
way to go. this is a big investment and i want it to last me a long
time. i don't want it falling apart in a year. but on the other hard,
i don't want to go crazy and pull out 2000 sf of tile when it's
possible there are alternatives.


any ideas? thanks very much!!

[Dave Taylor]

Thank you for visiting TYW forums and..... thank you for the clear explanation of requirements and options.

Because you state the following.....

i just want to know what you all think is the safest way to go. this is a big investment and i want it to last me a long time. i don't want it falling apart....

My druthers are with the plan proposed by tile guy #2.

Hope this helps.

[ceramictec]

Hi cdmariscal,

welcome to the forum.

as Dave said, we all here will agree its best to rip up the old tile and start from a clean slab.

your taking a chance of how well the tile was done, how well it was cleaned, how good of a bond the thinset got and how good the thinset is, and raising the new tile up at doorways and the edge.

porcelain tile is very hard and scuffing it will be a task. there are good quality thinset's out there that you can set tile over tile like a flex type of mortar that is highly modified, but there is now way you can use a regular thinset if you do attempt to tile over tile.

[cdmariscal]

Thanks Dave/Ceramictec for your response. Can you recommend a good quality thin set that may work? The folks at the place where i bought the tile recommended a product called Porcelain Set. thanks

[ceramictec]

all of the top thinset manufacturers flex or multi purpose thinsets are good these days.
its just a matter of your location and what brands are available.

porcelain set is a good thinset and it wouldn't hurt to mix in more addative in it.

[LGB]

I agree that the old tile should be removed. I would be worried about the quality of the work coming from someone quoteing $2 a square foot for 18x18 tile on an exterior application. Sounds fishy to me...