How to choose glass thickness for wind load

Step 1: fix the design load

GlassLoad.com does not work out wind load. Take the design wind pressure for the pane from your project, from the building code and the wind standard it names. It depends on the height, the exposure and the zone of the facade where the pane sits. Corner and edge zones carry more pressure than the middle of a wall.

Then follow the load rules of the glass standard. For E1300 you enter one design load, in psf or kPa. For AS 1288 you enter an ultimate pressure and a serviceability pressure. For EN 16612 you enter characteristic loads, and the partial factors of the standard are applied for you.

Step 2: fix the size, support and glass type

Enter the long and short dimension of the pane and say how its edges are supported. Four supported edges are stiffer than two. Choose annealed, heat strengthened or fully tempered glass. Choose monolithic, laminated or insulating glass where the standard and the tool allow it.

Wind is a short duration load, but snow and self weight last longer. If a pane carries both, the load duration can change the result, so enter it as the standard asks.

Step 3: try a thickness

Pick a trial nominal thickness and run the check. If the load resistance is lower than the design load, the pane fails. You then have three choices. Use thicker glass. Use a stronger glass type, such as heat strengthened or fully tempered glass. Reduce the span with another support or a smaller pane.

Remember that nominal thickness is a name. The calculation uses the thickness the standard gives for that name, which is usually a little less. E1300 lists it in Table 4. AS 1288 lists thicknesses in Table 4.1.

Step 4: let the tool find the minimum thickness

The minimum thickness finder runs the check for every thickness the standard offers and marks the thinnest one that passes. It needs a free account. The result is a starting point. The final choice also depends on stock sizes, cost, the glass supplier and the wishes of the design team.

Step 5: check deflection

A pane can carry its load and still bend too much. Check the deflection against the limit your project uses. The E1300 deflection in Appendix X1 is approximate and can differ from the true value by about 10 percent. The AS 1288 check uses its own deflection limit in Section 4. EN 16612 compares the deflection with an allowable value that you can change.

Step 6: record the result

Download the PDF report. It lists the inputs, every step and the warnings. Read the warnings, because some tell you that the pane is outside the range of the method. Results are to be verified by a qualified professional before anyone builds from them.

See it worked

The worked examples run each standard on the examples it prints. See E1300 24 Example 1 for a load resistance, AS 1288 Example 2 for a minimum thickness and EN 16612 Example 1 for strength and deflection. Then open the calculator and try your own pane. The guide to load resistance explains the E1300 steps, and the guide to AS 1288 and EN 16612 covers the two other standards. See also the questions and answers.