Design and Specification
What this domain tests
Domain 3 tests translating site facts and code requirements into coordinated drawings and specifications that can be bid, permitted, and built. Questions focus on basis of design, document hierarchy, substitutions, and constructability.
Core rules
- Basis of design. Record loads, environmental criteria, occupancy, performance targets, and assumptions.
- Drawings versus specifications. Drawings show geometry; specifications set quality, submittals, testing, and execution. Both are contract documents.
- Prescriptive versus performance. A performance specification sets outcomes; the contractor's submittal must demonstrate a compliant system.
- Substitutions. Require a written request, evaluation against specified criteria, and written approval. 'Or equal' is not automatic.
- Coordination. Resolve structural, electrical, mechanical, fire, and architectural interfaces; state tolerances and hold points.
- Order of precedence. Follow the contract's stated hierarchy; do not resolve document conflicts by personal preference.
Worked example
A contractor proposes a substitute component with a lower fire rating but faster delivery. Reasoning: compare the proposed item to the specified rating, listing, assembly, and AHJ acceptance. Delivery speed is not a technical basis. Reject it unless an approved alternate demonstrates equivalent performance and is accepted in writing.
Traps that cost marks
- Unit conversion errors in loads or dimensions.
- Specifying a product not listed for the intended use.
- Approving a substitution verbally or after installation.
- Missing interface details between trades.
- Letting a vendor drawing replace the design document.