Thinset Over PSA? - Tiling - Contractor Talk

Thinset Over PSA?

 
Thread Tools Search this Thread Display Modes
Old 06-21-2015, 08:06 PM   #1
Member
 
WBCarpentry's Avatar
 
Join Date: Jun 2015
Posts: 98
Rewards Points: 212

Thinset Over PSA?


So I'm doing a small bathroom that is about 40sf. Customer had 12x12 vinyl tile adhered with trowel on pressure sensitive adhesive on 5/8 plywood which is over 1/2 plywood. Why it's like this I have no idea. But anyway are you guys applying thinset over this psa and then putting down backerboard? I've never taken up a floor like this. Will
WBCarpentry is offline  

Warning: The topics covered on this site include activities in which there exists the potential for serious injury or death. ContractorTalk.com DOES NOT guarantee the accuracy or completeness of any information contained on this site. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task!

   

Advertisement

 

Old 06-21-2015, 08:42 PM   #2
Pro
 
Dan_Watson's Avatar
 
Trade: Remodeling Contractor/Helical Post Installer
Join Date: Mar 2008
Location: South Jersey
Posts: 4,294
Rewards Points: 2,594

Re: Thinset Over PSA?


Rip up the 5/8".

Based on joists and spacing, additional plywood as needed and then Ditra.

If using CBU, at least another 1/2" ply, thin-set, and CBU screwed down.

Advertisement

Dan_Watson is offline  
Old 06-21-2015, 09:08 PM   #3
Member
 
WBCarpentry's Avatar
 
Join Date: Jun 2015
Posts: 98
Rewards Points: 212

Re: Thinset Over PSA?


Thanks Dan. I figured that but wanted to make sure.
WBCarpentry is offline  
Sponsored Links
Advertisement
 
Old 06-22-2015, 09:22 AM   #4
Paul
 
PrecisionFloors's Avatar
 
Trade: Hard Surface Flooring
Join Date: Jan 2006
Location: South Florida
Posts: 4,120
Rewards Points: 1,004

Re: Thinset Over PSA?


I wouldn't rip it up if it is in good shape. Waste of labor and money. I also don't use cbu. Skim it with feather finish and use the membrane of your choice.
__________________
Precision Floors
(772) 237-9900
Tile, Hardwood, Laminate, and Resilient
Installation, Sales & Repair - "We do it right the FIRST time"
PrecisionFloors is offline  
Old 06-22-2015, 03:32 PM   #5
Pro
 
MIKE ANTONETTI's Avatar
 
Trade: FLOORING CONTRACTOR
Join Date: Jul 2012
Location: CITRUS COUNTY
Posts: 1,751
Rewards Points: 3,514

Re: Thinset Over PSA?


I see no reason to rip up. Thinset is not important to bond to psa. No chemical reaction should occur. The backer board would be fine. Also Precision's idea for sheet membrane or other.

I don't think there's a compression of the psa issue either since it's very thin.
MIKE ANTONETTI is offline  
Old 06-22-2015, 05:26 PM   #6
Pro
 
Dan_Watson's Avatar
 
Trade: Remodeling Contractor/Helical Post Installer
Join Date: Mar 2008
Location: South Jersey
Posts: 4,294
Rewards Points: 2,594

Re: Thinset Over PSA?


How is the second layer down? I don't trust second layers, to many issues normally. Not being fastened properly and layout matching the layer below are both common issues.
Dan_Watson is offline  
The Following User Says Thank You to Dan_Watson For This Useful Post:
MIKE ANTONETTI (06-22-2015)
Old 06-22-2015, 09:29 PM   #7
Member
 
WBCarpentry's Avatar
 
Join Date: Jun 2015
Posts: 98
Rewards Points: 212

Re: Thinset Over PSA?


The second layer is perpendicular to the first. I added additional screw to eliminate any possible squeaks. I'm just gonna key in the thinset good in the psa and then put my dens shield over it and proceed as normal. Thanks for all the input guys. Probably a dumb question but it was the first time I've worked with the psa.
WBCarpentry is offline  
Old 06-22-2015, 09:50 PM   #8
Pro
 
charimon's Avatar
 
Trade: Tile and Tool junkie
Join Date: Nov 2008
Location: Omaha NE
Posts: 1,857
Rewards Points: 1,168

Re: Thinset Over PSA?


I disagree with some of you here. The mortars I use; Tec 3n1, tec Full flex, expressly prohibit setting on it; Mapei Ultraflex 2, and Lati 253, do not include it in their list of suitable substrates even though cut back adhesive is listed. It is not listed as a suitable substrate for eco prim.

More to the point, I have removed 2 failed installs over PSA (on concrete) that were less than a year old in the last 9 months.
charimon is offline  
The Following User Says Thank You to charimon For This Useful Post:
Metro M & L (06-23-2015)
Old 06-22-2015, 09:53 PM   #9
Member
 
WBCarpentry's Avatar
 
Join Date: Jun 2015
Posts: 98
Rewards Points: 212

Re: Thinset Over PSA?


Well to that point I'll probaly just call Tec tomorrow and run it by them. I was hoping for a definitive answer but I see both sides.
WBCarpentry is offline  
Old 06-22-2015, 09:54 PM   #10
Pro
 
charimon's Avatar
 
Trade: Tile and Tool junkie
Join Date: Nov 2008
Location: Omaha NE
Posts: 1,857
Rewards Points: 1,168

Re: Thinset Over PSA?


If you were to install a CBU to that floor. I think i would still just grind it off. Yes off the wood. it would take less than an hour with a 7" and a chevron wheel. and then install durock and nail it well.
charimon is offline  
Old 06-23-2015, 05:04 AM   #11
Pro
 
MIKE ANTONETTI's Avatar
 
Trade: FLOORING CONTRACTOR
Join Date: Jul 2012
Location: CITRUS COUNTY
Posts: 1,751
Rewards Points: 3,514

Re: Thinset Over PSA?


Charimon, your example is different, I assume they set tile over psa, this guy was setting a backer board over the psa. The thinset would only act as a filler with the board mechanically fastened. So in theory psa can spread over concrete, thinset is Portland so the two would be chemically compatible.

Your failures were probably bonding issues with shear strength and tensile strength issues.

You know me and the equipment I have, I can grind that and put whatever has to go back down. Others don't have equipment for this first time he's run into it, but certainly guys will be running into this often as the sale of this adhesive is only gaining strength.

This equipment is a whole nutha level.
MIKE ANTONETTI is offline  
The Following 2 Users Say Thank You to MIKE ANTONETTI For This Useful Post:
charimon (06-23-2015), Metro M & L (06-23-2015)
Old 06-23-2015, 08:20 AM   #12
Paul
 
PrecisionFloors's Avatar
 
Trade: Hard Surface Flooring
Join Date: Jan 2006
Location: South Florida
Posts: 4,120
Rewards Points: 1,004

Re: Thinset Over PSA?


Which is specifically why I recommended encapsulate and a membrane. You guys seriously over think these things a lot of the time. I've never, and I mean never, had anything that Feather Finish won't stick to. Thing is, is I rely on my own experience over manufacturers specs more often than not. At the end of the day I'm the one really warrantying the job anyway.
__________________
Precision Floors
(772) 237-9900
Tile, Hardwood, Laminate, and Resilient
Installation, Sales & Repair - "We do it right the FIRST time"
PrecisionFloors is offline  
The Following 2 Users Say Thank You to PrecisionFloors For This Useful Post:
charimon (06-23-2015), Dan_Watson (06-23-2015)
Old 06-23-2015, 09:42 AM   #13
Pro
 
MIKE ANTONETTI's Avatar
 
Trade: FLOORING CONTRACTOR
Join Date: Jul 2012
Location: CITRUS COUNTY
Posts: 1,751
Rewards Points: 3,514

Re: Thinset Over PSA?


I agree with your method 100% Paul very viable option.
MIKE ANTONETTI is offline  
Old 06-23-2015, 11:49 AM   #14
Member
 
WBCarpentry's Avatar
 
Join Date: Jun 2015
Posts: 98
Rewards Points: 212

Re: Thinset Over PSA?


Who makes feather finish? I've never heard of it.
WBCarpentry is offline  
Old 06-23-2015, 01:18 PM   #15
Pro
 
MIKE ANTONETTI's Avatar
 
Trade: FLOORING CONTRACTOR
Join Date: Jul 2012
Location: CITRUS COUNTY
Posts: 1,751
Rewards Points: 3,514

Re: Thinset Over PSA?


I really never ever say this, but I'll make an exception OMG! No, just kidn, flooring installers know it well, it's an Ardex product for smoothing/patching floors.
MIKE ANTONETTI is offline  
The Following User Says Thank You to MIKE ANTONETTI For This Useful Post:
Metro M & L (06-23-2015)
Old 06-23-2015, 06:35 PM   #16
Paul
 
PrecisionFloors's Avatar
 
Trade: Hard Surface Flooring
Join Date: Jan 2006
Location: South Florida
Posts: 4,120
Rewards Points: 1,004

Re: Thinset Over PSA?


Quote:
Originally Posted by WBCarpentry View Post
Who makes feather finish? I've never heard of it.
Best floor patch on the market by about a mile or three. Sticks to anything, true feather edge, great pot life, impressive psi strength, easy to make a smooth as the proverbial baby's ass with little technique, as a skim coat it spreads for ever. About the only downside I can think of is it dries a bit slower than say Plani patch and is not as cheap by the pound. All of the other upsides far outweigh those though.
__________________
Precision Floors
(772) 237-9900
Tile, Hardwood, Laminate, and Resilient
Installation, Sales & Repair - "We do it right the FIRST time"
PrecisionFloors is offline  
Old 06-24-2015, 06:02 AM   #17
Pro
 
MIKE ANTONETTI's Avatar
 
Trade: FLOORING CONTRACTOR
Join Date: Jul 2012
Location: CITRUS COUNTY
Posts: 1,751
Rewards Points: 3,514

Re: Thinset Over PSA?


Most adhesives you can go over ardex feather finish when the adhesive spreading trowel will not dig in to patch. It is self drying. I've started doing this prior to confirming acceptability from Ardex. So it can de dark(wet) and product can be installed over it.

There are some fairly new skimcoat products that are close, but for 20 years, reps have been saying "try this product, it's just as good as FF."
MIKE ANTONETTI is offline  
The Following User Says Thank You to MIKE ANTONETTI For This Useful Post:
PrecisionFloors (06-24-2015)
Old 06-24-2015, 08:54 AM   #18
Paul
 
PrecisionFloors's Avatar
 
Trade: Hard Surface Flooring
Join Date: Jan 2006
Location: South Florida
Posts: 4,120
Rewards Points: 1,004

Re: Thinset Over PSA?


Agreed. When your sales pitch is "It's just as good as..." You've pretty much already told me I have no need to change lol.

Advertisement

__________________
Precision Floors
(772) 237-9900
Tile, Hardwood, Laminate, and Resilient
Installation, Sales & Repair - "We do it right the FIRST time"
PrecisionFloors is offline  
The Following User Says Thank You to PrecisionFloors For This Useful Post:
MIKE ANTONETTI (06-24-2015)


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Marble tile over Ditra or Blanke or Durabase w/ modified thinset? ND2 Tiling 13 01-09-2013 03:45 PM
Wall tiles in shower ? #1 Handyman Tiling 14 06-25-2012 09:45 PM
Can I used modified thinset here? Jackpine Savage Tiling 16 01-30-2011 10:13 AM
Thinset over old thinset... BuildersII Tiling 18 03-13-2010 08:39 PM
Thinset for flagging? Moneypit Masonry 7 02-06-2010 03:18 PM

Join Now... It's Fast and FREE!

I am a professional contractor
I am a DIY Homeowner
Drywall Talk is for
PROFESSIONAL CONTRACTORS ONLY!

At DrywallTalk.com we cater exlusivly to professional contractors who make their living as a contractor. Knowing that many homeowners and DIYers are looking for a community to call home, we've created www.DIYChatroom.com DIY Chatroom is full of helpful advices and perfect for DIY homeowners.

Redirecing in 10 seconds
No Thanks
terms of service

Already Have an Account?