National Building Granit Quarries Association Inc.
ASTM & GSA Specifications

As this specification does not include any reference to physical characteristics of granite, the Association recommends that the standards of ASTM and General Services Administration, which are identical, be followed.



Absorption by weight

0.40% max.




Density, Min:

160 lbs/CuFt
2,560 kg/m3




Modulus of Rupture, Min:

1,500 psi




Compressive Strength, Min:

19,000 psi




Abrasion Resistance, Min:





Flexural Strength, Min:

1,200 psi


The physical characteristics listed above represent strengths and abrasion resistance of granites tested dry on their strongest plane and have been historically used for building and structural use. Depending on the specific installation, there are many ways to test for the physical characteristics of granite including wet samples, dry samples and applying loads both perpendicular and parallel to the strongest plane.

See ASTM 615, Standard Specifications for Dimension Granite. Granite with strength or abrasion resisistance less than the minimum values listed above may be used provided that competent engineering evaluation shall consider both structural effects and material characteristics such as durability, permanent volume change, modulus of elasticity, thermal expansion and the like.

There is currently no test method recognized by ASTM for evaluation of the durability or performance over life cycle of a natural stone product. NBGQA recommends that whenever possible, existing installations of a particular granite be used as a measure of the material's ability to withstand the effects of environmental elements. The condition of the product after many years in actual service is a far more reliable indication of its ability to perform than an accelerated laboratory test. Most of the granites quarried by the National Building Granite Quarries Association, Inc. members have been in satisfactory use for many years and meet the above test criteria.

It is not within the scope of these specifications to address proper anchoring techniques or anchoring devices. The association recommends that all granite panels be adequately anchored using mechanical anchors. Reliance on adhesives without mechanical anchors is not recommended or endorsed by the association. Reference is made to ASTM Cl 242, Standards Guide for Design, Selection, and Installation of Exterior Stone Anchors and Anchoring Systems, and to ASTM C1201, Structural Performance of Exterior Dimension Stone Cladding Systems by Uniform Static Air Pressure difference, for information about suitability and use of various anchoring systems and devices.
Specifications for Architectural Granite Brochure
Specifications for Architectural Granite Brochure
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