How to read a structural engineer’s drawings

The structural drawings are the ones that keep a building standing. Here is a plain-English guide to what is on them.

On most residential jobs there are two sets of drawings: the architectural set (layout, dimensions, finishes) and the structural set from the engineer. For framing, the structural set is the source of truth for anything that carries load — and it overrides the span tables where it applies.

Beams and posts

Steel beams are usually called up as a UB (universal beam), UC (universal column) or PFC with a size, e.g. "200 UB 25". Posts and columns carry those beams down to a footing. The structural drawings show the size, the bearing points and how each connects — build to them exactly.

Lintels

Lintels span over door and window openings. The engineer sizes them to the load above; the schedule tells you the member and how far it bears each side. Undersize a lintel and the opening sags — this is not the place to guess.

Floor systems

For suspended floors, the structural set specifies bearer and joist sizes, spacings and spans — often LVL or I-joists. Where the drawings give sizes, use them; where AS 1684 governs, size to the span tables and add support at the span break.

Tie-down and bracing

The structural drawings also set out wind bracing and hold-down/tie-down — how the frame is stopped from lifting or racking. It is easy to overlook and critical for sign-off.

When in doubt, ask

If the architectural and structural sets disagree, the structural set wins for load — but the right move is to query it, not guess. That is exactly how we work at AWA.

Need a crew that reads the structural set properly and builds to it? See what we do or get a quote.