Field Sketching, Redlines, and Requests for Information

Why Field Sketching and RFIs Matter

On a structural steel job site, the printed drawing set is the legal document of record. But drawings are created months before steel is cut, and the field rarely matches the office perfectly. Dimensions get omitted, weld symbols conflict with the bill of materials, or a detail simply does not exist for a condition that showed up during erection. When that happens, welders and ironworkers do not guess and they do not proceed on assumption — they document the problem and get an answer in writing. Two tools make that happen: the field sketch and the request for information (RFI).

As a welder in the building and construction sector, you will be expected to read, mark up, and sometimes produce simple freehand drawings. You will also be expected to recognize when something on a drawing is wrong or missing and to communicate that clearly. These skills appear in NCCER Welding Level 2 coursework and are directly relevant to working under AWS D1.1, which requires that welds conform to qualified procedure specifications and approved drawings.

Field Sketching Conventions

A field sketch is a freehand drawing made on-site to record existing conditions, proposed changes, or details that are not shown in the contract documents. It does not need to be artistic, but it must be legible, labeled, and dimensioned.

Use these conventions every time:

• North arrow: Include one on any plan-view sketch so orientation is clear to anyone reading it later.
• Grid lines and column references: Reference the nearest structural grid intersection (for example, "Col. Line B/4") so the reviewer can locate your sketch on the contract drawings instantly.
• Scale notation: Freehand sketches are never truly to scale. Write "NTS" (Not To Scale) in the title block, or note an approximate scale such as "approx. 1 in = 1 ft" if you deliberately paced out proportions.
• Cloud-and-delta revision marks: Any change or addition to an existing drawing is circled with a freehand cloud shape. A small triangle (delta, Δ) containing a revision number sits outside the cloud. This is the industry standard way to show what changed and when.
• Title block information: Every sketch needs a title, your name, the date, the project name, and a sheet reference or unique sketch number.
• Dimensions: Write all dimensions with arrows pointing to the feature. Never leave a dimension implied.

AWS A2.4 Welding Symbols on Sketches

Whenever your sketch includes a weld, you must use the symbol system defined in AWS A2.4, Standard Symbols for Welding, Brazing, and Nondestructive Examination. Inventing your own notation is not acceptable on a structural project.

For a fillet weld — the most common weld in structural steel fabrication — the symbol elements you must show are:

1. Reference line: A horizontal line is the backbone of every welding symbol.

2. Arrow: Drawn from one end of the reference line, pointing to the joint. The side of the joint the arrow touches is the arrow side; the opposite side is the other side.

3. Weld symbol: A right triangle placed on the reference line. If it is below the line, the weld is on the arrow side. If above, it is on the other side.

4. Weld size: A number to the left of the weld symbol, indicating leg size in inches (for example, 5/16).

5. Weld length: A number to the right of the weld symbol, indicating the total length of weld in inches. If the weld is continuous and runs the full joint length, the length may be omitted, but it is good practice to include it.

6. Tail (if needed): A fork at the opposite end of the reference line is used to reference a welding procedure specification (WPS) or note.

On a T-joint field sketch, always double-check: Is the weld on one side or both? The symbol must match the physical condition.

Marking Up a Drawing — Redlines

A redline is a markup of a contract drawing done in red ink to show discrepancies, field-installed conditions that differ from the drawing, or proposed changes. Redlines are legal documents on most projects. Follow these rules:

• Use red ink only for changes; do not re-draw the entire sheet.
• Cloud every area you changed.
• Add a delta with a revision number and your initials and date.
• Never erase or white-out the original drawing information — cross it out with a single red line so the original is still readable.
• Write a brief note explaining each change: "DIM. CONFLICTS WITH DETAIL 4/S3 — SEE RFI-007."

Writing a Formal Request for Information

An RFI is a written question submitted by the contractor or subcontractor to the engineer of record (EOR) or architect when something in the contract documents is unclear, missing, or contradictory. It creates a paper trail and protects everyone.

A standard RFI form includes:

• RFI number: Sequential, starting at RFI-001 for the project.
• Date submitted and date answer required: Typically 5–10 business days is standard, but check the project's contract.
• Project name and number.
• Drawing sheet and detail reference: Pinpoint exactly where the problem is — for example, "Sheet S4, Detail 7, Grid B/3."
• Description of the discrepancy: State the facts plainly. "Weld symbol on Detail 7 calls for a 3/8-inch fillet weld. General note GN-5 on Sheet S1 states maximum fillet weld size for 1/4-inch plate is 3/16 inch. These requirements conflict."
• Contractor's suggested resolution (optional but helpful): "Contractor suggests conforming to GN-5 (3/16-inch fillet weld) pending EOR confirmation."
• Attachments: Attach the relevant drawing detail and your redline or field sketch.

Do not proceed with welding in the discrepant area until you receive a written answer — a verbal answer on the job site is not sufficient.

Safety Note

When walking a structure to gather field measurements for a sketch, you are working in an active construction zone. Wear your full PPE: hard hat, safety glasses, steel-toed boots, and high-visibility vest. Do not remove PPE to handle drawings or write notes. If you are near any welding operations, add appropriate eye protection. Never rest on or step over welded connections that have not been inspected and accepted.