As-builts and capstone: reading a full drawing set

A building is never built exactly as drawn. Pipes are rerouted around beams, walls shift to suit equipment, buried services find their way around boulders, and owners change their minds. At the end of the project, the owner needs an accurate record of what was actually built, so that the building can be operated, maintained, renovated and eventually demolished safely. That record is the as-built and record drawing set. This final lesson explains how as-built information is collected during construction and turned into record documents, and what owners receive at handover. It then brings the whole course together in a capstone: a systematic method for reading a complete drawing set, and a set of worked problems that combine the skills of every lesson, from scales and grids to schedules, structural callouts, elevations and coordination.

As-built drawings and record drawings

The terms are often used loosely, but they usually mean different things:

• As-built drawings (often called redlines) are marked-up copies of the construction drawings kept by the contractor and trades during construction, recording every deviation from the issued documents as the work is done.
• Record drawings are the final drawings prepared at the end of the project, usually by the designer or the contractor as the contract requires, incorporating the as-built information, revisions, instructions, change orders and RFI answers into a clean set.

The specifications (usually Division 01, in a section on project record documents or closeout submittals) say who keeps the as-built set, how often it must be updated, what must be recorded, and in what format the final record documents must be delivered. Many contracts make up-to-date as-built drawings a condition of monthly payment, because information recorded months later from memory is unreliable.

What to record

As-built drawings should record anything that differs from the issued documents or that will be concealed. Typical items include:

• Buried services: the actual location, depth and size of underground pipes, conduits, duct banks and structures, with dimensions tied to permanent features such as building corners or grid lines, and elevations of inverts and tops of pipe.
• Concealed work in walls, floors and ceilings: pipe and conduit routes, valves, cleanouts, junction boxes, dampers and access points that will be hidden.
• Changes in dimensions, locations and elevations of walls, openings, equipment and structure.
• Changes in products, materials and equipment, with references to approved substitutions and submittals.
• Field changes made in response to RFIs, instructions, change directives and change orders.
• Embedded items, sleeves, anchors and post-tensioning tendons, and openings cut after construction.

The test of good as-built information is simple: could someone who was not on site find the buried valve, avoid the conduit in the slab or locate the cleanout behind the finish, using only the record? Ties to two or more permanent points (triangulation), elevations or depths, and photographs taken before concealment make the answer yes.

Handover documents

At the end of construction, the owner receives a package of closeout documents, specified in Division 01 and the technical sections. Besides the record drawings, it typically includes:

• Operation and maintenance (O&M) manuals for equipment and systems, with product data, maintenance schedules and parts lists.
• Warranties and guarantees, with start dates and contacts.
• Approved shop drawings and product data.
• Test and inspection reports, commissioning reports, balancing reports and certificates, such as the fire alarm verification and sprinkler test certificates.
• Spare parts, extra materials ("attic stock") and keys.
• Training records for the owner's staff.
• A record BIM model and structured asset data, where required, for the owner's facility management systems.

Increasingly, owners require digital handover: a record model at LOD 500 for key elements, and asset data in a structured format such as COBie (Construction Operations Building information exchange), so that information flows directly into maintenance software rather than sitting in binders. Point cloud scans of ceiling spaces and walls before they are closed are another valuable record.

In the United States, closeout requirements usually come from Division 01 of the specifications and the contract (AIA A201 requires the contractor to keep at the site a record copy of the drawings, specifications, addenda, change orders and modifications, marked currently to indicate field changes, and to deliver it to the architect for the owner). Public owners and federal agencies often add detailed digital handover requirements such as COBie data.

Capstone: a method for reading a full drawing set

Throughout this course, you have learned to read each kind of drawing. On a real project, you must read them together, often under time pressure, to estimate, plan, build or check the work. A reliable method helps. The following sequence works for most building projects; experienced readers adapt it to their role.

• Orient: read the cover sheet, sheet index, general notes, abbreviations, legends and code summary. Note the issue status and revision of every sheet (Lessons 1 and 2).
• Site: read the survey, site plan, grading, servicing and erosion control drawings; note property lines, setbacks, finished floor elevation, utility connections and site constraints (Lesson 5).
• Building: read the architectural floor plans, roof plan, elevations and building sections to build a mental model of the building's size, shape, levels and spaces (Lessons 3, 4 and 6).
• Structure: read the structural general notes, foundation plan and framing plans; identify the structural system, grid, typical bays and critical elements (Lesson 7).
• Envelope and interiors: read wall sections, details, partition types and the door, window and finish schedules (Lesson 6).
• Systems: read the mechanical, plumbing, fire protection, electrical and technology drawings, starting with legends, single-line diagrams, riser diagrams and equipment schedules (Lessons 8 and 9).
• Specifications: read the table of contents, Division 01 and the sections for the work you are responsible for (Lesson 10).
• Questions and risks: record every question, apparent conflict and risk in a log, cross-check by grid area across disciplines, and turn genuine issues into RFIs (Lesson 11).

Questions to ask of every sheet

Capstone problems

The following problems combine skills from across the course, using a simple two-story office building with a 6 m (20 ft) structural grid of three bays by two bays, spread footings at columns and strip footings under the perimeter foundation wall.

Notice how much these problems depend on reading notes carefully and comparing disciplines. The arithmetic is simple; the skill is in finding the right numbers, knowing what they refer to, and noticing when they do not fit together.

Building your drawing-reading skills

Reading drawings is a skill that improves with practice. Ways to build it include:

• Reading every set you can get, including public tender documents, which many owners publish online.
• Walking a building under construction with its drawings in hand, comparing what you see with what is drawn.
• Doing takeoffs, even rough ones, which forces you to read every dimension and note.
• Sitting in on coordination meetings and RFI reviews, where experienced people discuss conflicts.
• Sketching details freehand to understand them, and asking designers and trades to explain what you do not understand.

The courses that follow build directly on this one: construction mathematics and measurement (CON-130), codes and regulations (CON-140), estimating (CON-200), scheduling (CON-210), building systems (CON-230), structures (CON-240) and construction technology and BIM (CON-260) all assume you can read a drawing set confidently.