Tempered glass
Tempered glass (sometimes referred to as toughened glass) is a type of safety glass that, when it breaks, shatters into small, relatively even pieces that do not have sharp edges. It can also withstand moderate heat.
It is used in situations where large shards of broken glass could cause a hazard, such as in shower doors, frameless glass doors, phone booths, mobile phone screen protectors, diving masks, and car side windows, or in situations where heat may be present, such as in fireplaces.
It is manufactured by a process of extreme heating and rapid cooling, or by a chemical toughening process, that induces compressive stresses in the surface of the glass and tensile stresses in the body of the glass. The internal portion of the glass remain fluid for longer than the outer surfaces during the manufacturing process. This means that an equal amount of tensile and compressive stresses are formed across the glass which allows it to become in the order of four times as strong as annealed glass.
Heat soaked tempered glass may be used in safety critical situations, such as glass railings. Tempered glass panes are heated to a temperature of around 550 degrees Fahrenheit for a few hours. This causes any unstable nickel sulfide inclusions (imperfections that may cause spontaneous breakage of the pane) to expand disproportionately to the glass, making the glass break. Only glass that has not broken is then used.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
The context, schemes, standards, roles and relevance of the Building Safety Act.
Retrofit 25 – What's Stopping Us?
Exhibition Opens at The Building Centre.
Types of work to existing buildings
A simple circular economy wiki breakdown with further links.
A threat to the creativity that makes London special.
How can digital twins boost profitability within construction?
The smart construction dashboard, as-built data and site changes forming an accurate digital twin.
Unlocking surplus public defence land and more to speed up the delivery of housing.
The Planning and Infrastructure Bill
An outline of the bill with a mix of reactions on potential impacts from IHBC, CIEEM, CIC, ACE and EIC.
Farnborough College Unveils its Half-house for Sustainable Construction Training.
Spring Statement 2025 with reactions from industry
Confirming previously announced funding, and welfare changes amid adjusted growth forecast.
Scottish Government responds to Grenfell report
As fund for unsafe cladding assessments is launched.
CLC and BSR process map for HRB approvals
One of the initial outputs of their weekly BSR meetings.
Architects Academy at an insulation manufacturing facility
Programme of technical engagement for aspiring designers.
Building Safety Levy technical consultation response
Details of the planned levy now due in 2026.
Great British Energy install solar on school and NHS sites
200 schools and 200 NHS sites to get solar systems, as first project of the newly formed government initiative.
600 million for 60,000 more skilled construction workers
Announced by Treasury ahead of the Spring Statement.
The restoration of the novelist’s birthplace in Eastwood.
Life Critical Fire Safety External Wall System LCFS EWS
Breaking down what is meant by this now often used term.
PAC report on the Remediation of Dangerous Cladding
Recommendations on workforce, transparency, support, insurance, funding, fraud and mismanagement.
New towns, expanded settlements and housing delivery
Modular inquiry asks if new towns and expanded settlements are an effective means of delivering housing.