granits tiles over underfloor heating lifting

Reply

  #1  
Old 01-07-15, 07:21 AM
Member
Thread Starter
Join Date: Jan 2015
Location: uk
Posts: 2
Received 0 Votes on 0 Posts
granits tiles over underfloor heating lifting

hi,

I recently fitted electric underfloor heating and then laid granite tiles over this. Now 2 months later, the grout started to crack and when I have looked further, the tiles are loose in one area. I left the tiles for a couple of weeks before turning the heating on and used flexible adhesive and grout. any ideas why this has happened and what do I stick the tiles back down with as I don't want to damage the underfloor heating and don't want to raise the level of the tiles in this area as the rest are ok

thanks in advance
 
Sponsored Links
  #2  
Old 01-07-15, 08:29 AM
Member
Join Date: May 2007
Location: USA
Posts: 1,607
Received 0 Votes on 0 Posts
Hi,

I know you're not from the USA so we'll require more detailed info.

Tell us the type of floor substrate you have. If it's concrete or wooden system. If wooden, please describe how it's constructed in detail.

What specific adhesive did you use? Is it pre-mixed in a bucket or powder that you mixed? What size notched trowel did you use and was any applied to the backs of the granite?

That'l do for now. UK or OZ

Jaz
 
  #3  
Old 01-07-15, 11:50 AM
czizzi's Avatar
Forum Topic Moderator
Join Date: Jul 2007
Location: USA
Posts: 7,376
Received 9 Votes on 7 Posts
used flexible adhesive
Check the label on what ever brand mastic you used. Mastics are not to be used with heating systems. My guess is that eventually, the whole floor may have issues.
 
  #4  
Old 01-07-15, 12:26 PM
Member
Join Date: May 2007
Location: USA
Posts: 1,607
Received 0 Votes on 0 Posts
That's what I'm thinking too czizzi, I think mastic may have been used although we're not sure yet cuz adhesive does not equal mastic. Thinset is also adhesive.

I've heard of good results even with mastic from people in oz. Hard to believe but maybe they have super mastics there.

Jaz
 
  #5  
Old 01-08-15, 09:16 AM
Member
Thread Starter
Join Date: Jan 2015
Location: uk
Posts: 2
Received 0 Votes on 0 Posts
Hi guys, thanks for answering.

I live in UK

I used a flexible adhesive specifically for granite floor tiles which was suitable for underfloor heating according to the packaging but can't remember what brand it was. it was a dry powder mixed in a bucket. trowel was approx. 6mm or a quarter of an inch. didn't apply to the back of the tile.

the substrate is timber joists with chipboard panels screwed on top.

keith
 
  #6  
Old 01-08-15, 12:08 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,967
Received 2 Votes on 2 Posts
Did you not use concrete backer underlayment on top of your subflooring embedded in thinset? It may explain part of the problem. You can't lay tile on wood very successfully. It absorbs too much of the moisture in your adhesive too quickly, and the wood does not have the ability to form a slip layer needed for tile.
 
  #7  
Old 01-08-15, 12:47 PM
czizzi's Avatar
Forum Topic Moderator
Join Date: Jul 2007
Location: USA
Posts: 7,376
Received 9 Votes on 7 Posts
chipboard panels
Can you provide a little more detail on what this means? We have something here in the states that is called particleboard, which is totally unsuited for most any type of flooring except carpet. Do you mean the same as OSB?

In the tile area where the stones have come loose, is the adhesive you used solid as a rock like a cement, or is is somewhat soft where you could indent it with a fingernail?
 
  #8  
Old 01-08-15, 06:56 PM
Member
Join Date: May 2007
Location: USA
Posts: 1,607
Received 0 Votes on 0 Posts
Keith,

With a 5 hour time difference we'll have to wait for answers.

Tiles are installed using different standards in the UK than here. Sometimes I wonder how any of the floors last. In addition, natural stone tiles require a much stiffer subfloor system than for ceramic.

So, timber joists? Size and the length of the span. Do you know their species and grade? Answer the above question of what "chipboard" means to you. How thick is it, is it tongue & groove, how many layers above the joists? You spread the adhesive direct to the chipboard? How old is the structure?

We need to know exactly what you used as the adhesive too. Flexible adhesive means nothing.

Jaz
 
Reply

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


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: