FHB Logo Facebook LinkedIn Email Pinterest Twitter X Instagram Tiktok YouTube Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Restoration
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In

Discussion Forum

Discussion Forum

Porcelain tile separating from gypcrete slab

Bigalb | Posted in Construction Techniques on January 20, 2016 08:53am

We recently had our kitchen renovated/enlarged and had radiant heating installed in a gypcrete slab. The floor is one story up over a new basement space and sits on 3/4 inch plywood on properly supported floor joists. Shortly after the kitchen was completed, we began to hear loud cracking noises coming from the kitchen floor and eventually realized that the 18×18 porcelain tiles were separating from the gypcrete. The result was that we had most of the tiles pulled up and reset and that seems to have solved the problem. Standard thinset was used and it looked like most of the thinset was still attached to the tile when it was removed. Why did this happen? The footings of the kitchen addition sit on the granite schist and are secured with rebar so there is no movement there. 

Reply
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

Replies

  1. calvin | Jan 20, 2016 09:27pm | #1

    A couple questions

    was the floor heat "on" during or shortly after the tile was set?

    how long after gyp installed was the tile set?

    were the tiles buttered with thin set?

    how long have the replaced tiles been down?

    1. User avater
      deadnuts | Jan 20, 2016 10:39pm | #3

      A couple?

      1. calvin | Jan 21, 2016 07:02am | #4

        Ok, 4

        Discussion of this situation on the board might put forth information for others to avoid this problem.

        no?

    2. Bigalb | Jan 21, 2016 07:52am | #5

      Answers to a couple of questions

      The heat was not on for a few weeks. The furnace and radiant heat system were not installed yet. The tiles were laid in thinset that had been spread on the slab. I can't remember how long after the gypcrete was poured, the tiles were laid but it might have only been a few days. The new tiles have been down for a few months and seem to be secure. 

  2. User avater
    deadnuts | Jan 20, 2016 10:36pm | #2

    Short answer: bond broke.

    So you already had your problem solved by having your tiles reset. Why are you interested in speculation ('cause that's all you're going to get here) vs. simply solving your problem and moving on. If its still a lingering question then it seems like the person(s) who did your renovation would be the best party to ask.

    1. Bigalb | Jan 21, 2016 07:54am | #6

      Bond broke

      my contractor said had had no idea why this happened and I was curious to see if any one else had a problem like this. 

      1. User avater
        deadnuts | Jan 24, 2016 07:33am | #9

        Was the contractor that repaired your tile problem the same contractor that created it in the first place?

  3. DanH | Jan 21, 2016 01:18pm | #7

    Clearly it's some combination of bond failure and differential movement. 

    My money would be a little on the side of bond failure being the main culprit.  I suspect that there was some efflorescence on the surface of the gypcrete and this prevented the thinset from bonding very well.  Reading up a little on gypcrete it appears that improper mixing could cause efflorescence to be worse than normal, and likely various site conditions could contribute to this as well.  One might wish to guard against this on newly-poured gypcrete by giving it an acid wash before using thinset.  Or perhaps using some sort of modified thinset would be appropriate.

    But the conditions present offered plenty of opportunity for differential movement as well.

  4. User avater
    deadnuts | Jan 24, 2016 07:31am | #8

    Sounds like a job where a decoupling membrane would have been appropriate. Ditra would have been my choice.

  5. Bigalb | Jan 24, 2016 08:05am | #10

    Same contractor

    same contractor, different tile guy. 

  6. User avater
    Mongo | Jan 28, 2016 06:51pm | #11

    Tile on gypcrete, not recommended...

    Get in touch with Maxxon tech and see what they have to say about their product.

    It's poor form to tile directly to gypcrete. Thinset and gypcrete do not play well together, especially when it's a direct tile-to-gypcrete installation over RFH. The gyprete isn't strong enough to handle any stresses put on it by differential movement. An intermediary like a membrane used between the two makes things go better.

    The following info may be outdated, thus the recommendation to get in touch wth Maxxon's tech department. But they used to recommend a product called Maxxon Overspray, it acted like a primer/sealer. Then an anti-fracture membrane over that. Then tile on the membrane.

    Hope you get things resolved.

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Video Shorts

Categories

  • Business
  • Code Questions
  • Construction Techniques
  • Energy, Heating & Insulation
  • General Discussion
  • Help/Work Wanted
  • Photo Gallery
  • Reader Classified
  • Tools for Home Building

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Up Next

Video Shorts

Featured Story

Making the Move to Multifamily

A high-performance single-family home builder shares tips from his early experience with two apartment buildings.

Featured Video

Video: Build a Fireplace, Brick by Brick

Watch mason Mike Mehaffey construct a traditional-style fireplace that burns well and meets current building codes.

Related Stories

  • Podcast Episode 692: Introduction to Trade Work, Embodied Carbon, and Envelope Improvements
  • FHB Podcast Segment: Embodied Greenhouse Gas Emissions and the Building Codes
  • Old Boots Learn New Tricks
  • Install Denim Insulation Like a Pro

Highlights

Fine Homebuilding All Access
Fine Homebuilding Podcast
Tool Tech
Plus, get an extra 20% off with code GIFT20

"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Fine Homebuilding Magazine

  • Issue 332 - July 2025
    • Custom Built-ins With Job-Site Tools
    • Fight House Fires Through Design
    • Making the Move to Multifamily
  • Issue 331 - June 2025
    • A More Resilient Roof
    • Tool Test: You Need a Drywall Sander
    • Ducted vs. Ductless Heat Pumps
  • Issue 330 - April/May 2025
    • Deck Details for Durability
    • FAQs on HPWHs
    • 10 Tips for a Long-Lasting Paint Job
  • Issue 329 - Feb/Mar 2025
    • Smart Foundation for a Small Addition
    • A Kominka Comes West
    • Making Small Kitchens Work
  • Issue 328 - Dec/Jan 2025
    • How a Pro Replaces Columns
    • Passive House 3.0
    • Tool Test: Compact Line Lasers

Fine Home Building

Newsletter Sign-up

  • Fine Homebuilding

    Home building tips, offers, and expert advice in your inbox.

  • Green Building Advisor

    Building science and energy efficiency advice, plus special offers, in your inbox.

  • Old House Journal

    Repair, renovation, and restoration tips, plus special offers, in your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters

Follow

  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X
  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences
  • About
  • Contact
  • Advertise
  • Careers
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2025 Active Interest Media. All rights reserved.

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

  • Home Group
  • Antique Trader
  • Arts & Crafts Homes
  • Bank Note Reporter
  • Cabin Life
  • Cuisine at Home
  • Fine Gardening
  • Fine Woodworking
  • Green Building Advisor
  • Garden Gate
  • Horticulture
  • Keep Craft Alive
  • Log Home Living
  • Military Trader/Vehicles
  • Numismatic News
  • Numismaster
  • Old Cars Weekly
  • Old House Journal
  • Period Homes
  • Popular Woodworking
  • Script
  • ShopNotes
  • Sports Collectors Digest
  • Threads
  • Timber Home Living
  • Traditional Building
  • Woodsmith
  • World Coin News
  • Writer's Digest
Active Interest Media logo
X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Project Guides
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Online Learning

  • Courses
  • Project Guides
  • Reader Projects
  • Podcast

More

  • FHB Ambassadors
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • X
  • YouTube
  • instagram
  • facebook
  • pinterest
  • Tiktok

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 70%

Subscribe

Enjoy unlimited access to Fine Homebuilding. Join Now

Already a member? Log in

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in

Privacy Policy Update

We use cookies, pixels, script and other tracking technologies to analyze and improve our service, to improve and personalize content, and for advertising to you. We also share information about your use of our site with third-party social media, advertising and analytics partners. You can view our Privacy Policy here and our Terms of Use here.

Cookies

Analytics

These cookies help us track site metrics to improve our sites and provide a better user experience.

Advertising/Social Media

These cookies are used to serve advertisements aligned with your interests.

Essential

These cookies are required to provide basic functions like page navigation and access to secure areas of the website.

Delete My Data

Delete all cookies and associated data