Safe insulating glass units produced using safe glass.
Safe glass is laminated, tempered or reinforced glass.
When making design of windows and outside doors, the following should be taken into consideration:
- purpose of use of the building premises and intensity of activity of their users, i.e. number of persons who can access glazing in critical areas and their activity;
- resistance of glass against strokes and way of breakage;
- measurement of glass in critical areas.
Glass safety is described by classes of glass resistance to strokes and type of breakage.
Glass properties and classes defining glass properties in accordance with LST EN 12600:
| Glass property | Glass class | Remarks |
| Resistance to stroke | 3, 2, 1 | 3 class glass – lowest resistance to strokes, 1 class – highest resistance to strokes. |
| Type of glass breakage | A | Glass breaks up into multiple different-sized sharp-edged pieces. This feature of glass breakage is typical of the ordinary glass hardener thermally and chemically. |
| B | Glass can crack or break, but glass pieces remain stuck to the film. This feature of glass breakage is typical of laminated glass covered with films and wire grid. |
|
| C | Glass breaks into multiple small pieces which are relatively harmless. This feature of glass breakage is typical of thermally hardened glass. |
The use of safety glass in Lithuania is regulated by Technical Regulations for Construction STR 2.05.20:2006 “Windows and outside doors”.
The following standards are used for classification of safety glass:
- LST EN 12600:2003. Construction glass. Pendulum test. Method and classification of shock test for sheet glass. This standard defines resistance of glass against strokes and type of breakage. Classification is applied for laminated and tempered glass (see Table 1.1 and 1.2).
- LST EN 356:2002. Construction glass. Protective window glass. Test of resistance against hand-stroke and classification. Glass classified according to this standard show the level of safety against break-in or fall. Only laminated glass is classified as safe according to this standard (see Table 2.1 and 2.2).
Glass classification according to EN 356 standard.
Marking of safety glass according to the classification by standard LST EN 356:2002.
| PVB laminated glass code |
PVB film thickness, mm | Glass thickness, mm |
Class according to EN 12600 |
| 33.1 | 0.38 | 6.4 | 2(B)2 |
| 44,1 | 0.38 | 8,4 | 2(B)2 |
| 55,1 | 0.38 | 10,4 | 1(B)1 |
| 33,2 | 0.76 | 6,8 | 1(B)1 |
| 44,2 | 0.76 | 8,8 | 1(B)1 |
| 44,4 | 1.52 | 9,5 | 1(B)1 |
| 44,6 | 2.28 | 10,3 | 1(B)1 |
| 55,2 | 0,76 | 10,8 | 1(B)1 |
| 66,2 | 0,76 | 12,8 | 1(B)1 |
| 88,2 | 0,76 | 16,8 | 1(B)1 |
Marking of tempered glass in accordance with the classification of standard LST EN 12600:2003.
| Thickness of tempered glass |
Class according to EN 12600 |
| 4 mm | 1(C)2 |
| 6 mm | 1(C)2 |
| 8 mm | 1(C)2 |
| 10 mm | 1(C)1 |
| 12 mm | 1(C)1 |
Glass classification according to EN 356 standard.
Marking of safety glass according to the classification by standard LST EN 356:2002.
| PVB laminated glass code |
Thickness, (mm) |
Weight (kg/m²) |
Class according to EN 356 |
Height, (mm) |
Number of throws* |
| 33.1 | 6.4 | 16 | – | ||
| 33,2 | 6,8 | 16 | P1A | 1500 | 3 |
| 44,1 | 8,4 | 21 | – | ||
| 44,2 | 8,8 | 21 | P2A | 3000 | 3 |
| 33,4 | 7,5 | 17 | P4A | 9000 | 3 |
| 44,4 | 9,5 | 22 | P4A | 9000 | 3 |
| 44,6 | 10,3 | 22 | P5A | 9000 | 3×3 |
| 66,6 | 13,5 | 32 | P5A | 9000 | 3×3 |
*Test with steel ball of 4.1 kg.
Data based on technical information of glass suppliers.
Marking of safety glass according to EN 356 Resistance against hand stroke (axe test).
| Class according to EN 356 |
Resistant to axe strokes | Thickness, (mm) |
Weight, (kg/m²) |
| P6B | 30-50 | 15 -:18 | 33 -: 42 |
| P7B | 51-70 | ~ 23 | ~ 53 |
| P8B | >70 | 28 -: 50 | 63 -:11 |