• Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
  • A&D
  • INSTALLATION
  • MARKETS
  • AWARDS
  • EDUCATION
  • BUYER'S GUIDE
  • MEDIA
  • EMAGAZINE
  • SIGN UP
cart
facebook twitter linkedin youtube
  • NEWS
  • Breaking Flooring News
  • eNewsletters
  • PRODUCTS
  • Carpet & Area Rugs
  • Hardwood
  • Installation Products
  • Installation Tools & Equipment
  • Laminate
  • Resilient
  • Specialty
  • Tile & Stone
  • MARKETS
  • Commercial
  • Residential
  • AWARDS
  • Installation Awards
  • Top Flooring Products
  • EDUCATION
  • Continuing Education
  • Webinars
  • MEDIA
  • FLOOR Podcast
  • Videos
  • TISE 2025 Videos
  • Product Spotlights
  • eBooks
  • EMAGAZINE
  • eMagazine
  • Archive Issues
  • Contact
  • Advertise
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
    • Breaking Flooring News
    • eNewsletters
  • PRODUCTS
    • Carpet & Area Rugs
    • Hardwood
    • Installation Products
    • Installation Tools & Equipment
    • Laminate
    • Resilient
    • Specialty
    • Tile & Stone
  • A&D
  • INSTALLATION
  • MARKETS
    • Commercial
    • Residential
  • AWARDS
    • Installation Awards
    • Top Flooring Products
  • EDUCATION
    • Continuing Education
    • Webinars
  • BUYER'S GUIDE
  • MEDIA
    • FLOOR Podcast
    • Videos
    • TISE 2025 Videos
    • Product Spotlights
    • eBooks
  • EMAGAZINE
    • eMagazine
    • Archive Issues
    • Contact
    • Advertise
  • SIGN UP
Flooring InstallationColumnsTile & Stone FlooringCTEF Tile Tip

How to Define Large-Format Tile and Its Subfloor Requirements

By Scott Carothers
installing large-format tile

Photo: Getty Images.

August 16, 2024

The term “large-format tile”, or LFT as it has become known, is a term that has been circulating through the U.S. tile world for over 20 years. 

According to the Tile Council of America Handbook 2001, under the header “Bonding Large-Format Tile for Coverage and Support” it states, “Large tiles are generally considered to be 8” x 8” and greater.” Under the “Subsurface Tolerance” header it states, thin-set tolerance to be ¼” in 10’, to conform with the ANSI specifications. However, the words “large-format tile” were not connected to the subfloor requirement.

In 2013, both the Handbook and ANSI A108 quote the now-familiar subsurface statement: “For tiles with all edges shorter than 15”, maximum allowable variation is ¼” in 10’ and for tiles with at least one edge 15” in length or longer, maximum allowable variation is 1/8” in 10’. Interestingly, the term “large-format tile” is missing. 

During the last 20-plus years, with tile getting larger and the need for a flatter substrate, the tile industry somehow mistakenly assumed and overused the statement that large-format tile was a tile 15” or longer, but neither ANSI nor the Handbook ever made that statement.

So, what is a large-format tile? At this point, there is a guy in the back of the room jumping up and down saying, “That can’t be right. Large-format tile is anything 15” or greater” and most folks in the tile industry would agree. More confusion.

Which ones are large-format tile?

Which of these would be considered large format tile? Photo: Scott Carothers.

Now, with the introduction of the ANSI A108, A118, A136 specifications in January 2024, the term “large-format tile” finally received a recognized definition. In that document, one of the new sections, A108.T, American National Standard Terminology of Tile Assemblies – 2023, lists the following definition: 

“Large Format Tile: A tile manufactured in conformance with ANSI A137.1 having a facial dimension greater than 23 in. (584 mm).”  

ANSI now provides a clearer standard for substrate flatness.

ANSI A108.02-4.2.1  Substrate flatness for tile shorter than 15 in. (0.38 m): For tiles with all edges shorter than 15 in. (0.38 m), the substrate shall have a maximum permissible variation of 1/4 in. in 10 ft. (6 mm in 3 m) from the required plane, and no more than 1/16 in. variation in 12 in. (2 mm in 305 mm) when measured from the high points in the surface.

ANSI A108.02-4.2.2 Substrate flatness for tiles 15 in. (0.38 m) or longer: For tiles with at least one edge 15 in. (0.38 m) or longer, the substrate shall have a maximum permissible variation of 1/8 in. in 10 ft. (3 mm in 3 m) from the required plane, and no more than 1/16 in. variation in 24 in. (2 mm in 610 m) when measured from the high points in the surface. 

Finally, with these updates to the ANSI A108, A118, and A136 document, we now know that an LFT is a tile greater than 23” and the flatness requirement for the substrate. Confusion gone!

See more articles from our Agust 2024 issue!

  • How to Moisture Test Hardwood and Subfloor for Hardwood Installation
  • Mohawk Embraces Culture of Care to Connect with Consumers and Flooring Dealers
  • The Good Plastic Company Transforms Plastic Waste into Sustainable Architectural Materials—Including Flooring
KEYWORDS: Ceramic Tile Education Foundation (CTEF) installing tile Large-Format Tiles subfloors

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Scott carothers 2025

Scott Carothers is the Academic Director of the Ceramic Tile Education Foundation (CTEF) headquartered in Mt. Juliet, Tennessee (Nashville area). In 2007, he was hired and tasked with creating the Certified Tile Installer (CTI) program and in 2012, he was part of the team that created the Advanced Certifications for Tile Installers (ACT) program. 

For eighteen years, he has been providing training and education to others in the tile industry. Carothers has been involved in the ceramic tile industry for over 44 years and was the owner of a successful retail store and installation firm prior to coming to CTEF. 

Carothers served as President and Chairman of the Board of the National Tile Contractors Association (NTCA), Chairman of the NTCA Technical Committee, named the NTCA Tile Person of the Year in 2005 and received the NTCA Ring of Honor in 2013. He is a voting member of the American National Standards Institute (ANSI), the Tile Council of North America (TCNA) Handbook, and NTCA Technical Committees. 

Scott has authored over 185 articles in tile industry print magazines including Floor Covering Installer, Tile, TileLetter, and eMagazine/Newsletter publications such as Floor Trends & Installation and TIleLetter along with covering numerous topics on the CTEF Blog, thereby sharing his knowledge and installation experience with his readers. Additionally, he recently retired from being a presenter and trainer for the NTCA Workshop and Regional Training programs and the NTCA Technical Hotline.

He may be contacted at scott@tilecareer.com or 864-222-2131.

Recommended Content

JOIN TODAY
To unlock your recommendations.

Already have an account? Sign In

  • resilient flooring

    The 7 Types of Resilient Flooring

    The resilient flooring category is comprised of many...
    Resilient Flooring
    By: Resilient Floorcovering Institute
  • QuickDrain USA’s ShowerLine linear drain

    Tips for Curbless Shower Installation Using a Linear Drain

    Consider these four tips when planning for a curbless...
    Installation How-To
    By: Darryl Jones
  • 2024 New Flooring Product Guide

    2024 New Flooring Products Guide

    We explore this year's introductions in area rugs,...
    Floor Coverings
    By: FLOOR Trends & Installation Editors
You must login or register in order to post a comment.

LHT article

Dennis Elrod
September 25, 2024
Wow! I had no idea there was a new definition.

Report Abusive Comment

Subscribe For Free!
  • eMagazine
  • eNewsletter
  • Online Registration
  • Manage My Preferences
  • Subscription Customer Service

Retailers Share Top Takeaways from Shaw Flooring Network Convention

Retailers Share Top Takeaways from Shaw Flooring Network Convention

Takeaways from the 2024 AHSG Convention & Member Outlook for 2025

Takeaways from the 2024 AHSG Convention & Member Outlook for 2025

Shaw Flooring Network Retailers Report Post-Election Sales Surge

Shaw Flooring Network Retailers Report Post-Election Sales Surge

What Shaw Flooring Network Dealers are Banking on for 2025

What Shaw Flooring Network Dealers are Banking on for 2025

More Videos

Popular Stories

Ken Ballin manning the Tools 4 Flooring booth in Tool Alley at TISE 2025

10 Tool Innovations Every Flooring Contractor Should Have on Their Wish List

RevWood American Originals.jpg

How Mohawk's Domestic Manufacturing Powers Growth in Challenging Times

Paul Hambidge

The Waterproof Laminate Myth: Why Consumer Expectations May Never Be Met

Installation Awards - Vote Now!

Events

December 1, 2030

Webinar Sponsorship Information

For webinar sponsorship information, visit www.bnpevents.com/webinars or email webinars@bnpmedia.com.

View All Submit An Event

Poll

Flooring Groups

Flooring retailers, do you belong to a buying, marketing or franchise group?
View Results Poll Archive

Products

2025 BNI Interiors Square Foot Costbook

2025 BNI Interiors Square Foot Costbook

See More Products

FLOORtalk podcasts - Listen Now

Related Articles

  • marble shower with iron oxide discoloration

    Marble Tile in Showers: A Cautionary Tale

    See More
  • kitchen floor

    Regrouting Caution for Cement Grouts

    See More
  • Shower installation D. W. Sanders

    No Drill Holes: A Cautionary Tale of a Shower Installation Gone Wrong

    See More
×

We’re rolling out the red carpet of flooring knowledge!

Stay in the know on the latest flooring retail trends.

JOIN TODAY!
  • RESOURCES
    • Advertise
    • Contact Us
    • Directories
    • Store
    • Want More
  • SIGN UP TODAY
    • Create Account
    • eMagazine
    • eNewsletters
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • Instagram
    • YouTube
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing

search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
    • Breaking Flooring News
    • eNewsletters
  • PRODUCTS
    • Carpet & Area Rugs
    • Hardwood
    • Installation Products
    • Installation Tools & Equipment
    • Laminate
    • Resilient
    • Specialty
    • Tile & Stone
  • A&D
  • INSTALLATION
  • MARKETS
    • Commercial
    • Residential
  • AWARDS
    • Installation Awards
    • Top Flooring Products
  • EDUCATION
    • Continuing Education
    • Webinars
  • BUYER'S GUIDE
  • MEDIA
    • FLOOR Podcast
    • Videos
    • TISE 2025 Videos
    • Product Spotlights
    • eBooks
  • EMAGAZINE
    • eMagazine
    • Archive Issues
    • Contact
    • Advertise
  • SIGN UP