DA DB-SUA / 1 – Classification of Glass Impact Performance and Breakage Patterns
The DA DB-SUA / 1 is a technical support document issued by the Ministerio de Fomento through the Secretaría de Estado de Vivienda y Actuaciones Urbanas in Spain. Published in June 2011, it serves as an official interpretive guide for the Código Técnico de la Edificación (CTE), specifically complementing the Documento Básico DB-SUA (Safety of use and accessibility). The document provides technical clarification on the application of the UNE-EN 12600:2003 standard regarding the classification of flat glass products used in buildings based on their performance under impact and their specific breakage characteristics.
The regulatory scope of this document centers on section SUA 2, which addresses safety against the risk of impact or entrapment, particularly subsection 1.3 concerning impact with fragile elements. It establishes the criteria for selecting glass to limit risks of laceration and accidental falls through glazing where height differences exceed 55 cm. The text details the X(Y)Z classification system, which maps to the α(β)φ parameters defined in the European standard, and describes the standardized pendulum test used to simulate human impact against glass surfaces.
This reference document provides the necessary technical thresholds for architects and engineers to specify glass types—such as laminated safety glass or thermally toughened soda lime silicate safety glass—that meet Spanish building safety requirements. It defines the relationship between physical glass properties, tested performance levels, and the specific hazards present in different architectural configurations.
The X(Y)Z Classification System
The document defines glass performance using the three-part X(Y)Z notation, which corresponds to the α(β)φ parameters of the UNE-EN 12600 standard. These values indicate how the material behaves during a standardized pneumatic pendulum impact test.
- Parameter X: Represents the drop height (1, 2, or 3) at which the glass either does not break or breaks according to specific safety criteria. Value 1 represents the highest resistance.
- Parameter Y: Refers to the mode of breakage, determined by the glass manufacturing process (Type A, B, or C).
- Parameter Z: Indicates the drop height at which the glass breaks specifically with the characteristics of laminated glass. This value can be 0 if the glass breaks without meeting these conditions at the lowest test height.
Classification of Breakage Modes
Glass is categorized into three types based on the fragments produced upon failure. This classification is independent of impact resistance and depends solely on the material's manufacturing and treatment.
- Type A: Characterized by numerous cracks and large, sharp fragments. Typical of annealed glass, heat-strengthened soda lime silicate glass, and chemically strengthened glass.
- Type B: Characterized by numerous cracks where fragments remain adhered and do not separate. Typical of laminated safety glass, wired glass, and annealed glass with reinforced film.
- Type C: Characterized by disintegration into small, relatively harmless particles. This breakage mode is typical of thermally toughened soda lime silicate safety glass.
Impact Risk and Height Thresholds
The document establishes requirements based on the difference in floor level (cota) on either side of the glass. The primary objective is to prevent cutting and, in cases of significant height differences, to prevent falling through the opening.
- Level difference < 0.55 m: The primary risk is cutting. Glass must have a Type B or Type C breakage mode. Parameter X must be at least 3.
- Level difference ≥ 0.55 m: Risks include both cutting and falling. Glass must be Type B or Type C. For this category, parameter Z is critical and must be at least 1 or 2 to ensure the glass provides containment or breaks safely.
In areas where the drop exceeds 12 meters, the document specifies more stringent requirements, such as the use of glass classified as 1(C)1 or 1(B)1.
Frequently Asked Questions
What does the Parameter Y indicate in glass classification?
Parameter Y refers to the breakage mode (Type A, B, or C) determined by the manufacturing process, such as whether it is laminated, tempered, or annealed.
What glass classification is required for a drop height of less than 55 cm?
Glass must be classified as at least 3(B)3 or 3(C)3 to ensure it breaks safely and minimizes the risk of cuts.
When is Parameter Z relevant in building safety?
Parameter Z is relevant when there is a risk of falling from a height of 0.55 m or more, as it identifies glass that maintains containment or breaks with laminated characteristics.
What are the characteristics of Type C breakage?
Type C breakage involves the glass disintegrating into many small, relatively harmless particles, which is characteristic of thermally toughened safety glass.
Can annealed glass be used in high-risk impact areas?
Annealed glass, which has a Type A breakage mode, is generally not permitted in risk areas unless it is treated with a reinforced film to achieve Type B characteristics.
How is glass impact resistance tested according to DA DB-SUA / 1?
Impact resistance is tested using a pneumatic pendulum dropped from three different heights against a glass specimen fixed in a frame, as per UNE-EN 12600.
