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Curtain Wall Mullion Tributary Dead Load Calculator

Calculate the glass dead load carried by a curtain wall mullion from its tributary area.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-27 · v1.1.0

Market
Imperial · sales tax
4.92 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Mullion tributary dead load

248.02 lb

High confidence

For the dimensions entered, expect a mullion tributary dead load of 113 kg. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Mullion tributary dead load = tributary width × tributary height × glass weight per unit area, the standard tributary-area method for assigning distributed load to a supporting structural member

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Frequently asked questions

What is a mullion's tributary area?
It's the portion of the surrounding glazed wall area that a given mullion is assumed to support — typically extending halfway to each neighboring mullion or support, using the standard tributary-area load-distribution method.
Does this include the mullion's own self-weight?
No — this calculates the glass dead load carried by the mullion from its tributary area only. The mullion's own weight and any additional attached components (gaskets, pressure plates, etc.) are separate and should be added if needed for a full dead load total.
How do I find the glass weight per area for my makeup?
Use the actual surface density of your specified glass makeup — for example, 10mm monolithic glass is roughly 25 kg/m². For laminated or insulated glass units, sum the surface densities of each pane and interlayer, or use the manufacturer's stated unit weight.