Laminated or tempered?

A laminated pane consists of two or more sheets of glass with an interlayer between them. When it breaks, the fragments largely stay held on the interlayer.

Tempered glass has been heat-strengthened, and when it breaks it disintegrates into many small pieces rather than into large sharp shards. The choice follows from the position, the use, the dimensions and the safety requirements.

Both are safety glass; they differ in how they break. Laminated glass is made of two or more panes with an interlayer between them, and after breakage it holds the fragments and largely stays in the opening — which is why it is required in overhead glazing, in atriums, glass roofs and canopies, and in glass balustrades. Tempered glass has been heat-strengthened and breaks into many small pieces instead of large sharp blades. Classification is to EN 12600, and the choice follows from position, use, dimensions and the safety requirements.

Where each is required

Overhead glazing — atriums, glass roofs, canopies: laminated on the underside, so that fragments are held by the interlayer.
Balustrades and glass railings: laminated, because after breakage the pane has to stay in place.
Doors and surfaces at impact height: tempered or laminated depending on the requirement; the classification is to EN 12600.

Two details that are rarely mentioned

Toughened glass (EN 12150) can, rarely, break spontaneously because of nickel sulphide inclusions. The risk is reduced by heat soak testing to EN 14179 — asked for where a failure would be dangerous or expensive. Laminated glass (EN ISO 12543) has two further advantages that have nothing to do with safety: it cuts almost all ultraviolet radiation and improves sound insulation.

Laminated and tempered side by side

	Laminated	Tempered
Structure	Two or more sheets with an interlayer between them	A single heat-strengthened sheet
Behaviour on breakage	The fragments largely stay held on the interlayer	Disintegrates into many small pieces rather than large sharp shards
Stays in the opening?	Largely yes	No
Contributes to noise reduction	Yes, particularly in asymmetric build-ups	Only to a limited extent

Both are safety glass. The choice follows from the position, the use, the dimensions and the safety requirements.