Overview
- Primary topic
- Glass deflection calculator
- Engineering basis
- SLS deflection
- Review status
- Project-specific verification required
SLS Glass Deflection Review
VitraLab reports serviceability deflection separately from ULS stress. The result shows the calculated movement, selected limit and any warnings, making it easier to compare the pane response with the project criteria.
Span, Thickness, and Support Type
Deflection is sensitive to pane span, glass thickness, aspect ratio, and support condition. Four-edge, two-edge, and one-edge support models can produce very different results.
Deflection Review
Wind Load and Structural Glazing
Facade glass and curtain wall glazing are often governed by wind suction or pressure. Deflection should be checked together with stress, support details, and framing assumptions.
Laminated Glass Deflection
Laminated glass deflection depends on the ply thicknesses, interlayer assumptions and load duration. The entered build-up should match the project specification.
Vertical and Horizontal Glazing
Vertical glazing, rooflights, canopies, balustrades, and horizontal glass can have different serviceability expectations, drainage issues, and visual movement limits.
Engineering Use
Result Review
The output should be checked against project specifications, support stiffness, fixing details, local requirements, and engineering judgement before final design use.
Example Structural Glass Deflection Checks
Example VitraLab deflection outputs for laminated glass, DGU glass and balustrade-style support conditions.
Swipe horizontally to view more figures
Frequently Asked Questions
What is glass deflection?
Glass deflection is the movement of a pane under service load. It is usually reviewed separately from stress because a pane can be strong enough but still too flexible for the project.
What affects glass deflection most?
Pane span, thickness, support condition, load magnitude, aspect ratio, laminated glass assumptions, and selected serviceability limit all affect deflection.
What glass deflection limit should I use?
Use the limit required by the project specification and applicable design basis. VitraLab reports the selected limit and utilization, but the engineer must confirm that the criterion is appropriate for the glazing system and its supports.
Is SLS deflection the same as ULS stress?
No. SLS deflection reviews serviceability movement, while ULS stress reviews strength under design load combinations.
Can wind load govern glass deflection?
Yes. For facade and structural glazing, wind pressure or suction can control the deflection check even when stress utilization is acceptable.
Engineering content is prepared and maintained by VitraLab Engineering. Worked examples show how the current calculator treats a defined case; they do not replace project-specific verification.