The Method You Choose to Specify a Product Affects Competition, Quality, and Risk
When an architect writes a specification, the method used to describe a required product or material determines how much control the architect retains, how much competition exists among bidders, and where the responsibility for product performance lies. Four methods appear in ARE PDD content: proprietary, descriptive, performance, and reference standards. Each is legitimate; the appropriate choice depends on the situation, the owner's priorities, and the design team's level of product knowledge. Understanding the trade-offs helps architects make deliberate specification decisions rather than defaulting to one method.
Proprietary Specification
A proprietary specification names a specific manufacturer and product: "Provide Tremco Proglaze II silicone sealant at all exterior glazing joints." Advantages: precise control over product quality; useful when a specific product is essential to the design or has been tested by the architect or owner; reduces risk of substitution with inferior products. Disadvantages: may limit competition (raising bid prices), may be challenged by public procurement rules requiring competition. Proprietary specifications may be used as "basis of design" with "or approved equal" language to allow competition while setting a clear performance benchmark.
Descriptive Specification
A descriptive specification details the required physical and chemical properties without naming a brand: "Provide latex paint: VOC content less than 50 g/L, spreading rate minimum 400 sf/gallon, reflectance minimum 88% for white." Any product meeting all the stated characteristics is acceptable. Advantages: promotes competition; allows many manufacturers to bid. Disadvantages: difficult to write completely; may inadvertently describe only one or two products anyway; requires technical knowledge to specify all critical characteristics.
Performance Specification
A performance specification states the required end result or functional performance without describing how it is achieved: "Provide exterior curtain wall system with maximum air infiltration of 0.06 cfm/sf at 6.24 psf differential pressure and maximum water infiltration of 0 cfm/sf at 12 psf." Any system that can demonstrate it meets the performance criteria is acceptable - the contractor and manufacturer choose how to achieve it. Advantages: maximum contractor flexibility and innovation; responsibility for achieving performance shifts to the contractor. Disadvantages: loss of architect control over product type; requires rigorous testing and verification protocols to confirm compliance.
Reference Standard Specification
A reference standard specification requires conformance with an industry standard: "Provide Portland cement concrete conforming to ACI 318 for structural elements." Advantages: leverages established industry expertise; clear, defensible criteria. Disadvantages: standards may not address all project-specific requirements; must be current edition unless specified otherwise. Reference standards are often combined with other methods - a performance specification may reference ASTM test methods to define how performance is measured.
Comparison Summary
| Method | Specifies | Competition | Architect Control | Contractor Responsibility |
|---|---|---|---|---|
| Proprietary | Specific brand/product | Low | Maximum | Low |
| Descriptive | Physical properties | High | High | Moderate |
| Performance | Required outcome | Maximum | Low | Maximum |
| Reference standard | Industry standard | High | Moderate | Moderate |
Key Exam Points
- Proprietary: specific brand; maximum control; least competition.
- Descriptive: physical properties; promotes competition; requires complete description.
- Performance: end result; maximum contractor flexibility; shifts responsibility to contractor.
- Reference standard: cites industry standard (ASTM, ACI, ANSI).
- "Basis of design with approved equals" combines proprietary (for quality benchmark) with competition.
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