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

Cantilevering TJI joists

fly840 | Posted in Construction Techniques on November 2, 2007 04:01am

I have read many posts reference my question and I am still a little foggy.  I have already built a 24 foot by 34 foot ICF basement.  The 34 foot side will be a walkout basement.  On top of that, I am ready to deck and would like to cantilever four feet over the front of the building (the walkout side).  The joists will run along the 24 foot axis and will be 28 feet long to make up the cantilever.  I seem to be getting conflicting reports from the manufacturer.  On top of this first floor deck, and, on top of the cantilever, I will be putting up SIP walls, an attic deck, and a SIP roof, the peak running the same direction the first floor joists run.  

The joists that have been specified for the first floor cantilevered deck are Ilevel 360, 16 inch, 12″ on center, 28 foot joists.  I have gone over their installation guide numerous times and still do not completely understand the blocking necessary, especially having to do with the cantilever.  

Is this really doable and is there any other resource that I can go to online to see a chart about cantilevering TJI joists and can you build on top of it?

I am building this house largely by myself in Alabama, no inspections are required, but, I want it done right.

Thank you very much if you have anything to add.

Bill 

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

Replies

  1. JTC1 | Nov 02, 2007 04:24am | #1

    I believe it is probably doable ------ but, I would contact the manufacturer directly. Ilevel?

    As a general rule the manufacturer's are quite helpful with information.  I asked a similar question of Louisiana Pacific -- manufacturer of LPI's.

    They sent me a written reply to my specific questions and a copy of their "Design Manual" which contains w-a-y more information than the installation guide packed with the I joists.

    Incidently, when talking to them - don't call them TJI's -- that is their competition's product.

    Jim

    Never underestimate the value of a sharp pencil or good light.

  2. User avater
    BossHog | Nov 02, 2007 04:30am | #2

    I seriously doubt that 16" I-joists would cantilever 4' and carry the loads you described without some sort of reinforcement. And standard load charts for the I-joists aren't gonna go that far.

    The only way I can see that you can get a definitive answer is from the engineering department of the manufacturer. If they're giving you conflicting reports, keep on their butts until they give you a definite answer.

    Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so. [Gore Vidal]
    1. Jim_Allen | Nov 02, 2007 06:28am | #3

      What Boss said. FKA Blue (eyeddevil)

  3. Stilletto | Nov 02, 2007 01:20pm | #4

    On a cantaleiver I did a few years back they wanted an LVL so often in the layout instead of a joist,  corners and every 6 ft after that. 

    Then the plans called for 3/4" plywood nailed to both sides of each joist.  Starting from the rim joist and back over the cantaleiver 8'. 

    You might be able to do it if you have it engineered for it. 

    Matt- Woods favorite carpenter. 

  4. JohnFinn | Nov 02, 2007 03:07pm | #5

    48" isn't common but can be done. Ilevel or their subsidiaries engineering department should be able to come up with a design for this. You may end up using microlams or a combination microlam/I joist for this. The back span is what is critical here, as the amount of weight from the cant. will want to "pick up" the floor at the endspan of the joists (on interior/inside). These should be tied down at bearing (probably at least 10' back of your walkout wall over bearing). Also, consider moisture content on the outside spans, you may need a treated material which will affect what is used here).

    1. fly840 | Nov 02, 2007 04:12pm | #6

      Thanks all for your quick responses.  I am on my way to the supplier now and I believe in the interest of conservatism, I will pull the cantilever back to two feet if he can't give me a definitive answer.

      Again, I appreciate all the help.

      Bill

      1. Framer | Nov 02, 2007 04:23pm | #7

        Bill,If you really want the 4' cantilever, you can ask about using 3-1/2" x 16" or 5-1/4" x 16" microlams for that section.Joe Carola

        Edited 11/2/2007 9:28 am ET by Framer

        1. fly840 | Nov 02, 2007 04:28pm | #8

          Thanks Joe,

          I think I will have plenty of room with the two feet, I was being greedy:)  It is a lake house after all and we will only be sleeping in this part anyway.  Thanks again for the help.

          Bill

          1. User avater
            Gene_Davis | Nov 02, 2007 05:19pm | #9

            Have you read and understood the tech info available from I-Level as downloads from their site?

            Cantilevered spans, loadings, and details are presented there.

            I am surprised you would ask here, in a forum of mostly words, spoken by strangers with unknown qualifications.

            You need drawings, tables, charts, and specs.  All are available from I-Level.

          2. Jim_Allen | Nov 02, 2007 05:51pm | #10

            Gene stop it.You prefer charts, I prefer seat of the pants engineering. Of course, I've been involved in some serious fixes of engineering that was scientifically done and screwed up royal.
            FKA Blue (eyeddevil)

          3. fly840 | Nov 03, 2007 02:21am | #11

            I don't find them the easiest to understand, and yes, I have downloaded and studied them all.  But hey, I'm only an airline pilot:)  I'm going with the 2 foot cant. and hoping for the best.  Well, with my architects blessing.

            Bill

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

A New Approach to Foundations

Discover a concrete-free foundation option that doesn't require any digging.

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

  • Old House Air-Sealing Basics
  • A Drip-Free, Through-Window Heat Pump
  • Insulation for Homes in the Wildland Urban Interface
  • An Impressive Air-to-Water Heat Pump

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
  • Old House Journal – August 2025
    • Designing the Perfect Garden Gate
    • Old House Air-Sealing Basics
  • Issue 329 - Feb/Mar 2025
    • Smart Foundation for a Small Addition
    • A Kominka Comes West
    • Making Small Kitchens Work

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