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

Cutting tempered glass

| Posted in Construction Techniques on October 17, 2003 03:13am

Not really cutting, but read on…

Just had a large reputable glass co install some large picture windows.  About 6’8″ h x 8’6″ wide, two layers of 1/4″ tempered glass with an insulation gap.  Took 6 guys, they estimated it weighed about 525#.  The glass was made to the exact size specified (they did the measuring) and the frames were made to the same size, thus there was essentially no room to get the glass into the frames.  The lead guy, 20+ yrs experience, took out his RO sander and shaved down the top edge of the glass, and they were able to squeeze it in.  I asked him later about what he did, and he said that since the glass breaks into 1/4″ pieces they can take off as much as 1/8″ if necessary.  I didn’t know that…is he right?  In my case, all he really did was clean off the excess glue and goop from the edge of the sandwich.

 

Do it right, or do it twice.

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

Replies

  1. WayneL5 | Oct 17, 2003 04:00am | #1

    I believe he's asking for trouble.  I was an engineer designing a process to temper glass windows for a specialty product.  I'm not a ceramic engineer by education, so I learned a lot from others.  In thermally tempered glass the compressive surface layer is about 1/4 of the thickness.  So, for a 1/4" thick pane, the layer is about 1/16".  If you go deeper than that the glass shatters.  As for the edge, I never had to deal with that in my situation, so I never asked how deep along the edge it goes.  So, not knowing, if it were me I would not do it.

    Of course, he may have done it successfully before.  Even if he did not understand what he was doing, his experience may have told him it was ok.  His reasoning based on the size of the pieces is certainly all wet, though.

    I would not jam glass into a frame so tightly.

  2. junkhound | Oct 17, 2003 04:31am | #2

    really did was clean off the excess glue and goop .....

    ou ought to be OK then.

    when a kid, tried to cut/grind/drill tempered glass, always a shattering experience.

  3. HeavyDuty | Oct 17, 2003 04:47am | #3

    >>he said that since the glass breaks into 1/4" pieces they can take off as much as 1/8" if necessary

    Did you really believe him? That's funny though.

    If he takes off as much as 1/8", then if the glass does break, the pieces along the edge would be 1/8" instead of 1/4". Now do you believe this?

    Is this a residential installation? That's a monster piece of glass.

  4. nigelUsa | Oct 17, 2003 04:55am | #4

    The glass is that tight in the frame? hope it does not move or settle much.

    1. FastEddie1 | Oct 17, 2003 05:07am | #5

      Here's a pic.  The client wanted a clear view of the ranch...the dining room table will be in front of the glass.

      I didn't really believe him, although he didn't appear to be BS'ing me...I think he was telling what he really thought.  He did explain that the glass was not jammed into the frame, but there was barely enough clearance to get it in...once in it was fine.  And it's warrantied for 5 yrs so hopefully any problems will show before then.

      Well, my picture allowance is used up...now I get to figure out how to delete attachments.  I read the current thread and will try that.

      Do it right, or do it twice.

      Edited 10/16/2003 10:07:56 PM ET by ELCID72

      1. joeh | Oct 17, 2003 05:20pm | #10

        Came with a warranty that covers beltsander modifications?

        Joe H

      2. don26299 | Oct 18, 2003 05:28am | #19

        ELCID72,

        What is "the current thread"? I just had the same "used up" problem come up & haven't been able to get a reply.

        1. FastEddie1 | Oct 18, 2003 06:19am | #20

          Fonz..."deleting old attachments" in General Discussion.Do it right, or do it twice.

    2. hasbeen | Oct 18, 2003 06:33am | #22

      Reminds me of a shed I saw on a piece of land that was for sale.  The owner had taken a piece of tempered glass about three feet high and four feet wide, installed it with only one flat 2x4 of knotty rough sawn lumber as a "header" with rafters right on top of it.  (Shed was about 10 feet wide)   A FIVE FOOT WET SNOW DIDN'T BREAK IT!!! 

      Structural glass?Any jackass can kick down a barn, but it takes a carpenter to build one.

  5. User avater
    IMERC | Oct 17, 2003 05:11am | #6

    Sorry to say that the glass is now under compressive tension and it's gonna break at the slightest provocation... That glass needs expansion room. It's too tight in the frame.

    BTW glass is nick sensitve.

     

    Who ever invented work didn't know how to fish....

    1. junkhound | Oct 17, 2003 05:45am | #7

      compressive tension .....

      please explain that term, as in tension compressed concrete???

      1. User avater
        IMERC | Oct 17, 2003 07:18am | #8

        It is what it says 

        Who ever invented work didn't know how to fish....

        1. FastEddie1 | Oct 17, 2003 02:53pm | #9

          Maybe compressive stress?  Compressive tension seems to be like a double negative in English, and that'll get red marks on the paper.

          Do it right, or do it twice.

          1. User avater
            IMERC | Oct 17, 2003 06:57pm | #12

            OK... 

            Who ever invented work didn't know how to fish....

  6. PhillGiles | Oct 17, 2003 06:30pm | #11

    I don't know if this would apply to a sealed unit, like you're described; but, the mirror guys 'scribe-fit' wall-to-wall mirrors with a belt sander all the time. The ones I've seen all use those little 1" wide portable belt units.

    .

    Phill Giles

    The Unionville Woodwright

    Unionville, Ontario

    1. NormKerr | Oct 17, 2003 07:06pm | #13

      Phill, I think those mirrors are all plate glass.

      Plate glass is very soft and easy to work with (belt sanding the edges works fine).

      Tempered glass is highly stressed and that gives it the strength, but even the tinyest nicks can provide a place for that stress to go above the limit of what the glass material is capable of resisting and then it shatters.

      When tempered glass shatters the chip size is made by the shock wave as it bounces from one face of the glass to the other. The thickness of the tempered surfaces (think of the glass as a glass sandwich, the hardened glass is the bread and the meat is untempered "plate" glass). When the tempering is done evenly the chips are all the same size.

      Since the tempered glass provides its own stress, it only takes a nick (no need to apply any outside load, just a nick) and off it goes!

      Norm

  7. geob21 | Oct 18, 2003 02:44am | #14

    First glass that size should be sitting on at least 1/4" rubber pads.

    I replace alot of insulated glass and clearence should never be an issue. Many units when made in a shop are slipped, meaning both glass sheets are not perfectly in line. this is ok because clearence around all edges on a unit that size should be no less then 3/8".

    Cleaning off high spots in the with a razor blade is not a problem but grinding the glass tells me it's not the correct size. Any settlement, expansion or contraction is going to spell trouble. If you don't get broken glass I'll bet you'll get seal failures but it'll take more then 5 years for them to really show themselves.

    The glass breakage size is really some left handed BS that he obviously had to learn in the 20 years he hasn't been able too master reading a tape.

    _________________________________________________________

    If you were arrested for being a quality builder would there be enough evidence to convict you?



    Edited 10/17/2003 8:04:05 PM ET by GEOB21

  8. Clay | Oct 18, 2003 03:19am | #15

    The glass does need room around it for movement.  They make rubber pads for this purpose that are about 1/8" thick.  Glazing suppliers have them.  You should have either reordered the glass or routed out the frame to fit it.  It will likely have a very short lifespan now.  If the glazing company did the measuring make them change it out. 

    1. FastEddie1 | Oct 18, 2003 04:02am | #16

      I did absolutely nothing except call them to the site and writte a check.  On things like this, I don't want any involvement in case something happens, so they can't say I gave the wrong dim or whatever.

      Here's a pic...

      Do it right, or do it twice.

      1. User avater
        JeffBuck | Oct 18, 2003 04:36am | #18

        got some news for ya...

        you wrote the check ...

        you are now the glass GC ...

        it's your problem now.

        You bought the responsibility with that check.

        Hope you added your 15% to their total to pay for the time you have to spend to fix their mistake and make things right now.

        JeffBuck Construction   Pittsburgh,PA

         Fine Carpentery.....While U Waite                  

        1. FastEddie1 | Oct 18, 2003 06:22am | #21

          Jeff, you're right with respect to my relationionship between the owner and the glass co.  But my point was that I let the glass co do everything their own way, so the measure and fab and installation is all their responsibility.  And what do you mean 15%?  I add way more than that.

          Do it right, or do it twice.

    2. SonnyLykos | Oct 18, 2003 04:27am | #17

      Back around 1977 I had a patio door glass shatter after about 2-3 years of installation in the house I built for us. It shattered for no aparent reason and was on an inside porch that was screened in so no sun hit it and no birds or stones hit it. I was in the kitchen where the door was when it happened. The glass company said it was from "tension compression" from when it was assembled at the factory with too little of a clearance.

      I was surprised since it was an aluminum door because I assumed the frame would deflect before it would have shattered. The guy from the glass company said one never knows "exactly" how glass is effected when under compressed tension in any particular situation.

      If that was the case, and is the case in this installation, I sure hope when/if it does shatter down the road, there are no people (or pets) standing next to it. Lawsuit heaven.

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

FHB Summit 2025 — Design, Build, Business

Join some of the most experienced and recognized building professionals for two days of presentations, panel discussions, networking, and more.

Featured Video

How to Install Cable Rail Around Wood-Post Corners

Use these tips to keep cables tight and straight for a professional-looking deck-railing job.

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