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Unread 03-09-2007, 01:25 PM   #1
tazman
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Slab in bad shape!

Hey guys... I read often and only post when I can’t find the answer. I think I have read plenty on this subject but this is my problem.

I have taken on a project in which a lady just had a wood floor removed from the slab here in Florida - 14 years old approx 700 sf.... the floor was glued to the slab with 100% coverage and they actually used a jack hammer to get it off !!! the floor is now an absolute mess. There is glue residue everywhere that I think could be scraped "mostly" off... but they gouged the floor pretty severely with the hammer.

She has tentatively picked out a 20 x20 porcelain tile but is waiting for my advise before purchasing it….

Questions...

(1) Even if the glue scrapes up, did it seal the slab? I tested with water and it gets absorbed but takes a while.
(2) How clean does the floor have to be for Ditra ?
(3) SLC over all off it including glue??
(4) Best way to patch missing "chunks" ? - can I use thinset ?

Thanks in advance for you advise !!

Scott
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Unread 03-09-2007, 03:20 PM   #2
tazman
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No comments ?

Anyone ???
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Unread 03-09-2007, 09:37 PM   #3
George K
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I'll start you off, but I'm no expert .

The larger the tile, the flatter the floor needs to be. 20" by 20" is big tile, so it it will be less tolerant of imperfections in flatness. I'm sure you read that right?

1. Are you sure the water was absorbed and not evaporated? I've read 5 or 10 minutes to be absorbed.

2. Ditra over concrete requires unmodified thinset. Floor to be flatted first and clean enough to meet the thinset manufacturer's spec for bonding before laying the Ditra.

3. If the glue can be removed, that would be best. SLC needs a primer to be applied to the substrate before the SLC pour. Will the primer bond to your "glue" residue? I do not know. There is glue and then there is mastic and then there is cutback.
Do you know what you have?

4. Thinset is not for major leveling.

My guess the experts will say a mud bed as first choice if you can take the height. Get some numbers on how flat that slab is, so that they can have something to work with. A lot will depend on how bad things are and how much SLC would be required.

Good luck,
George
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Unread 03-10-2007, 08:26 AM   #4
tazman
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Thanks George !!

The larger the tile, the flatter the floor needs to be. 20" by 20" is big tile, so it it will be less tolerant of imperfections in flatness. I'm sure you read that right? Yes knew that and yes the size scares me !

1. Are you sure the water was absorbed and not evaporated? I've read 5 or 10 minutes to be absorbed. Definetly wasnt 5-10 min..

2. Ditra over concrete requires unmodified thinset. Floor to be flatted first and clean enough to meet the thinset manufacturer's spec for bonding before laying the Ditra. Safe to assume that if it was clean enough for them that I could lay it directly to the slab? This is the "big" question

3. If the glue can be removed, that would be best. SLC needs a primer to be applied to the substrate before the SLC pour. Will the primer bond to your "glue" residue? I do not know. There is glue and then there is mastic and then there is cutback.
Do you know what you have?
Fairly certain it's something like liquid nails..

4. Thinset is not for major leveling. Just for patching the missing chunks... not leveling ?

My guess the experts will say a mud bed as first choice if you can take the height. Get some numbers on how flat that slab is, so that they can have something to work with. A lot will depend on how bad things are and how much SLC would be required.

I dont think I could afford the height required to bed it... I have not been able to get there to actually lay a level on it and I am more concerned with giving her an answer to whether or not she should pursue tile ??

Thanks again and thanks to any that chime in !

Scott
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Unread 03-10-2007, 07:36 PM   #5
Davy
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I would get all the glue up for sure, that alone could be a job. It's hard to say about what's best to do with the slab without seeing it. If there are places where the surface is still showing and the gouges are 1/4 inch deep or less, I would probably skim coat it with thinset and use a medium bed thinset to set the tiles with.

If you want to put down a membrane, I would fill the gouges with thinset and rub it down with a rubstone. Then sweep, vacuum and mop it well and use Protecto Wrap along with the primer. Protecto Wrap would be a better choice for an anti-fracture membrane than Ditra.
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Unread 03-10-2007, 07:39 PM   #6
George K
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Scott,

Thinset looses it's strength rapidly with thickness. I do not think it is intended to be used for patching.

Why don't you drop an e-mail to Mr. Flat Floor, after you get a look with that level and ruler. I think it would be unwise and premature to give that lady an answer before you do both.

George
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Unread 03-12-2007, 11:43 AM   #7
tazman
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Thanks guys !! She is a friend and knows that I am researching this before jumping in... gouges are definetly deeper than 1/4 ! Some are a good 4-5 inches wide and 1/2 inch deep easy.

Protecto Wrap and primer ??? I know what the wrap itself is but the primer ??
surface is still showing ??

George... I am trying to get there this week and will touch base when I do... maybe some pics if I can.

Thanks again and if anyone has anymore to add.... Please do !

Scott
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Unread 03-12-2007, 01:12 PM   #8
sandbagger
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Scott - if there is still significant areas with glue you prolly want to look at something like a scarifier to get a clean surface. Sounds like quite a project.
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Unread 03-12-2007, 04:15 PM   #9
tazman
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Yes.... quite a project indeed !!!! It gets to the point that you become afraid to let freinds know what you "like" to do, or are capable of !! Being good at it doesnt help either...... and everyone figures your free !
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Unread 03-12-2007, 04:52 PM   #10
flatfloor
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After the glue comes off, sounds like a SLC job. Fast but expensive. Without seeing it, I'm guessing 30 bags.
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Unread 03-13-2007, 04:16 AM   #11
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How expensive? will it bond to a slab that has the residue in it ?
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Unread 03-13-2007, 07:02 PM   #12
flatfloor
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$25-30/bag Custom Levelquik at HD. Nope, you have to get the glue off or at least down to a shadow. Sorry.
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Unread 03-14-2007, 10:23 AM   #13
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sorry FlatFloor..... down to shadow ??
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Unread 03-14-2007, 10:31 AM   #14
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To the point that you can see the concrete thru it.
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Unread 03-14-2007, 10:52 AM   #15
tazman
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sorry to sound so ignorrant but even if the glue gets scraped to that point.... wouldnt there still be a residue "in" the concrete ??
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