A Buildability Review is Plumb's Tier 1 review: a systematic review of a shop drawing package for common drawing, documentation, coordination and fabrication issues. The question it answers is whether the package gives a competent fabricator enough information to build, finish, ship and install the work without guessing or calling the detailer.
It covers what is on the sheets: dimensions that chain and close, weld symbols with size, type and length, material grades and thicknesses, finish and coating callouts, bills of material that match the drawings, general notes that agree with details and schedules, pick points and weights, and by-others items called out. Every finding is placed on the sheet it came from, given one of five severities (Critical, Major, Minor, Comment, Advisory) and marked PE-Review-Required or not.
It does not cover engineering. It does not check whether a connection is adequate, whether a member is sized correctly or whether the design meets code. Anything that needs a licensed engineer's judgment is isolated and flagged for one, and the review approves, certifies and stamps nothing.
How Plumb uses the term
Tier 1 is the everyday review for any trade and any package, and every plan includes it. The full list is on /categories; a finished example is the sample review.