9.2 Specification Writing Methods & the Drawings–Specifications Relationship

1. Specification Writing Methods

Landscape architects utilize four distinct specification writing methods, each distributing design liability, quality assurance, and competitive pricing differently:

                               SPECIFICATION METHODS
                                         |
        +-----------------+--------------+--------------+-----------------+
        |                 |                             |                 |
   Proprietary       Descriptive                   Performance       Reference Standard
 (Brand/Model)     (Properties)                   (End Results)       (ASTM/ANSI/AASHTO)
        |                                               |
   +----+----+                                     Transfers Design
   |         |                                      Risk to Contractor
 Closed    Open ("or approved equal")

1. Proprietary Specifications

Proprietary specifications designate specific manufacturer brand names, product models, and catalog numbers:

• Closed Proprietary (Sole-Source): Names a single manufacturer and model, permitting no substitutions. Used when matching existing materials on a historic campus, maintaining single-source maintenance inventory, or meeting proprietary client technology.
  • Public Bidding Restriction: Strictly prohibited on most public works projects by federal, state, and municipal competitive bidding statutes to prevent monopolies and price inflation. If sole-sourcing is necessary in the public sector, the public agency must execute a rigorous administrative "sole-source justification" proving no viable alternatives exist.
• Open Proprietary: Names one or more acceptable manufacturers and products, but includes an "or equal" or "or approved equal" clause. This allows bidding contractors to propose alternative products, provided they submit documentation during the bidding phase proving the substitute matches or exceeds the specified product's aesthetic, physical, and functional characteristics.

2. Descriptive Specifications

Descriptive specifications detail all physical, chemical, dimensional, and aesthetic characteristics of materials, along with the precise process of fabrication and installation, without referencing any manufacturer brand names:

• Example: Specifying a custom site bench by describing 2-inch by 2-inch square tubular 316 stainless steel framework with 0.120-inch wall thickness, all joints fully welded and ground smooth, finished with FSC-certified sustainably harvested ipê hardwood slats measuring 1.5 inches by 3.5 inches with radiused edges.
• Risk / Liability Allocation: The landscape architect retains full design liability. If the contractor builds the product exactly in accordance with the descriptive specifications, but the bench flexes or rusts under normal use, the landscape architect bears professional responsibility for the defective specification.

3. Performance Specifications

Performance specifications define the required end results, operational criteria, structural loads, and testing standards, leaving the choice of materials, engineering design, and fabrication methods entirely to the contractor or manufacturer:

• Example: Specifying a segmental retaining wall to withstand a surcharge load of 250 psf, retain a 12-foot vertical soil height, achieve a minimum safety factor of 1.5 against sliding and overturning, utilize non-corrosive geogrid reinforcement, and withstand 100 freeze-thaw cycles per ASTM C1262 with < 1% mass loss, requiring the contractor to submit signed/sealed engineering calculations by a licensed structural engineer.
• Risk / Liability Allocation: Transfers design and fabrication liability to the contractor/manufacturer. The contractor guarantees the final assembly meets the prescribed performance thresholds.

4. Reference Standard Specifications

Reference standard specifications incorporate established consensus standards published by recognized testing and professional organizations, such as:

• ASTM International (e.g., ASTM C936 for Solid Concrete Interlocking Paving Units; ASTM C33 for Concrete Aggregates)
• ANSI (American National Standards Institute)
• AASHTO (American Association of State Highway and Transportation Officials)
• AmericanHort (publishers of ANSI Z60.1 American Standard for Nursery Stock, the authoritative standard for root ball dimensions, caliper measurements, container sizes, and plant form)
• CMHA (Concrete Masonry & Hardscapes Association)

Reference standard specifications are legally defensible, concise, and widely understood by commercial contractors. When citing reference standards, the specifier must ensure that the standard applies directly to the specific application and verify whether optional grades or testing criteria within the standard must be explicitly designated.

---

2. Relationship Between Drawings and Specifications

A fundamental doctrine of construction law is that Drawings and Specifications are legally complementary. What is required by one is as binding as if required by both. They are designed to work together as a unified set of Contract Documents without unnecessary duplication.

The Danger of Duplication

Landscape architects must avoid duplicating specification requirements on drawing sheets (e.g., writing elaborate soil amendment chemical recipes or asphalt mix designs directly on detail sheets). When information is duplicated, any design revision that modifies the specification without simultaneously editing the drawing note creates an inherent document discrepancy, exposing the owner to contractor change order claims.

Resolving Discrepancies and Order-of-Precedence Clauses

When a direct conflict occurs between drawings and specifications (e.g., the drawings show 60mm unit pavers, but the specifications require 80mm heavy-vehicular unit pavers), how is the conflict resolved?

1. The Modern Standard AIA Position (AIA A201 Section 1.2.1): Standard AIA contracts do not include an arbitrary order-of-precedence clause stating specifications automatically supersede drawings. Instead, the contract documents are complementary, and the contractor has an affirmative duty to review documents and immediately submit a Request for Information (RFI) to the landscape architect for professional clarification before proceeding.
2. Customized Public Order-of-Precedence Clauses: Many municipal, state, and institutional contracts include an express Order-of-Precedence Clause to establish a rigid legal hierarchy. A common public agency hierarchy is: $\text{Signed Agreement} > \text{Addenda} > \text{Supplementary Conditions} > \text{General Conditions} > \text{Specifications} > \text{Drawings}$ Within drawings, large-scale details typically govern over small-scale plans, and figured (written) dimensions govern over scaled measurements.
3. The "Higher Quality / Greater Quantity" Rule: Many public and commercial contracts contain a standard protective provision stating: "In the event of an irreconcilable conflict between drawings and specifications, the contractor shall be deemed to have estimated the work based upon the greater quantity, the higher quality, or the more stringent requirement."

---

3. Specification Writing Methods: Comprehensive Comparison

---

4. Real-World Case Scenario: The Permeable Paver Discrepancy

Scenario: A landscape architect designs a high-traffic pedestrian transit plaza for a municipal agency. On Sheet L-501 (Paving Details), the graphic detail section for permeable unit pavers shows a paver depth of "60 mm (2-3/8 in)" with an annotation calling for pedestrian loading. In Section 32 14 13.19 (Permeable Interlocking Concrete Paving) under Part 2 - Products, the text explicitly specifies: "Permeable interlocking concrete pavers shall be 80 mm (3-1/8 in) thickness, conforming to ASTM C936, suitable for intermittent maintenance and emergency vehicular loading." During bidding, no contractor submits an RFI regarding the paver thickness. The winning contractor orders and installs 60mm pavers. During a pre-final inspection, the landscape architect notices the thinner pavers, rejects the installation, and directs the contractor to remove and replace them with 80mm pavers at the contractor's expense. The contractor files a formal claim, arguing that the drawings govern because they depict the physical installation.

Analysis & Contract Resolution: Under the contract's Supplementary Conditions and standard municipal procurement provisions:

1. Technical specifications govern qualitative standards, material performance, and material grades, whereas drawings establish layout, geometry, and location. Paver thickness and load-bearing rating (ASTM C936) are qualitative material properties governed by the technical specifications.
2. The contract contained a standard conflict clause establishing that "where specifications and drawings conflict regarding material quality or dimension, the contractor is obligated to provide the higher quality or more stringent requirement." An 80mm paver rated for vehicular loading is structurally superior to a 60mm pedestrian paver.
3. The contractor had a contractual duty under AIA A201 Section 3.2 to study the contract documents and report discrepancies. By failing to submit an RFI during bidding, the contractor assumed the financial risk. The landscape architect acted fully within contractual authority to reject the non-conforming 60mm pavers.

---

5. Exam Traps & Pitfalls

1. The 16-Division Legacy Trap: Exam questions may attempt to confuse candidates by referencing obsolete 16-division numbering, such as placing planting or irrigation under "Division 2: Site Work." In modern MasterFormat, earthwork is Division 31, exterior improvements (paving, fences, irrigation, planting) are Division 32, and civil storm drainage is Division 33.
2. Part 1 vs. Part 2 vs. Part 3 Misplacement: A favorite LARE question tests where specific items belong within the 3-part SectionFormat:
   • Warranties, Mockups, Installer Qualifications, Submittal Procedures: Belong in Part 1 - General.
   • Manufacturer Lists, Material Grades, Concrete Mixes, Soil Ratios: Belong in Part 2 - Products.
   • Substrate Inspection, Preparation, Compaction Testing, Cleanup, Protection: Belong in Part 3 - Execution.
3. Closed Proprietary Specs in Public Bidding: Candidates often assume that naming a single proprietary brand is acceptable in public contracts if the designer believes it is the best product. Closed proprietary specifications are illegal on public projects unless an official sole-source exemption has been formally executed.
4. The Order-of-Precedence Assumption: Candidates often assume that specifications always legally supersede drawings under standard AIA contracts. Standard AIA Document A201 establishes that documents are complementary and assigns no automatic precedence, requiring the design professional to interpret ambiguities upon inquiry.