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Blast-Resistant Fenestration Rating Checker

Check whether a glazing's published blast hazard rating meets a project's required protection level.

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 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Achieved GSA performance condition

2 GSA Condition

High confidence

PASSES — the glazing's published performance condition meets or exceeds the project's requirement. Note: this tool only compares published, independently-tested GSA/ASTM F1642 ratings — it does NOT compute blast pressures, impulse loads, or dynamic rebound response itself. Full blast-resistant glazing design requires specialized SDOF/finite-element software (e.g. WINGARD, HazL) per UFC 3-340-02/ASTM F2248, performed by a qualified blast engineer.

Required condition
3 GSA Condition

For the dimensions entered, expect a achieved gsa performance condition of 2 GSA Condition. Of the working steps, required condition dominates at 3 GSA Condition. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

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

  • Full blast-resistant glazing design (dynamic rebound, pressure-impulse response) requires specialized SDOF/finite-element software (WINGARD, HazL) per UFC 3-340-02/ASTM F2248 — it cannot be reduced to a simple formula. This tool instead compares a glazing's already-published ASTM F1642/GSA hazard rating against the project's required performance condition, both on the standard GSA scale where a LOWER number is better (1 = best/no hazard, 5 = worst)

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Frequently asked questions

Does this tool calculate blast pressures or predict how the glass will actually respond to an explosion?
No. This tool only compares two already-established numbers — a glazing's published ASTM F1642/GSA hazard rating and the project's required performance condition. It does not model blast pressure, impulse, dynamic rebound, or fragmentation, all of which require specialized SDOF or finite-element software (e.g. WINGARD, HazL) per UFC 3-340-02/ASTM F2248, run by a qualified blast engineer.
Where do I find a glazing product's GSA performance condition?
It comes from independent ASTM F1642 test reports commissioned by the manufacturer, usually published on the product's technical data sheet or a GSA-approved product listing. Do not estimate or assume this value.
Why does a lower GSA condition number mean better performance?
The GSA scale is inverted from what you might expect: Performance Condition 1 represents no hazard (best), while Condition 5 represents the highest hazard (worst). A glazing 'passes' when its achieved condition number is equal to or lower than the project's required condition number.