Tempered vs heat-strengthened glass. Did You know

[@sweepEaway]

I didn't know! I'm a licensed c-17 glazier. I knew the strength differences. but I did not know that in hi/rise heat strengthened would be better? It still seams dangerous if they were to fall? Or is tempered recommended in hi-rise. I always thought tempered was best for safety..?

[@LearnGlazing]

Hello SweepEaway, that's a great yet complicated question. It all comes down to codes and the safety requirements of the building. Typically, all the players involved and the engineers must determine if falling glass poses a danger to people passing by. When broken, tempered glass is highly likely to fall, whereas HS glass tends to only fracture. So unless some sort of projectile hit the glass creating a void all of the glass is typically present to hold itself in place. You are right, tempered glass is safer for impact and falling debris. But, there are specific rules for when impact-resistant glass is needed. In the code's eye, not all glass is likely to see an impact. HS glass has outstanding thermal stability, its flatness and light transmission is close to that of annealed glass and much better than that of tempered glass. HS Glass is 3 times more resistant to thermal stress in comparison to normal annealed glass. Basically, It has some of the strength of tempered glass, but without the optical distortion. This makes heat-strengthened a great choice for windows in high-rise buildings, which must be able to resist high winds, while still providing optical clarity

[@sweepEaway]

@@LearnGlazing thank you

[@LearnGlazing]

@@sweepEaway Not a problem at all. Thank you for watching our video.

[@aynafishka7220]

@@LearnGlazing thank you! that's a great explanation with details!

[@LearnGlazing]

@@aynafishka7220 Thank you and thanks for the support.

[@bugbunny1306]

What glass would you use on boat portlightis 5"x15"?

[@gregcorwin8316]

polycarbonate

[@bay1795]

Can heat strengthened glass be cut?

[@gregcorwin8316]

The short answer is no. The long answer is that by definition, tempered glass has a minimum surface compression of 10,000 psi or greater, while heat strengthened has a surface compression range of 3,500 to 7,500 psi. IF the heat strengthened glass is at the very low end of the surface compression range then it MIGHT be possible to successfully cut it but it's going to be hit or miss at best.

[@LearnGlazing]

Greg is correct. Once you change the surface to internal molecular structure of glass by heat treating it, then it’s a huge gamble that would is likely to pop.

[@gregcorwin8316]

@@LearnGlazing Yep, and just to clarify that I was talking about the low end of the heat strengthened glass and not tempered. Tempered can never be cut or drilled or notched or so on...not with hand tools, not with lasers, not with waterjet....doesn't matter, can't do it.