Reading Architectural Plans: A Homeowner’s Visual Guide

Most home buyers feel uneasy reading architectural plans, but the conventions are quite consistent. Here is what each element means.

Floor plan basics

• Solid black lines: External walls (typically 270mm thick for brick veneer).
• Thinner solid lines: Internal walls (typically 90 to 120mm thick).
• Dashed lines: Hidden elements (overhead beams, hidden cabinetry, edge of roof line).
• Arc lines through openings: Doors. The arc shows which way the door swings.
• Parallel lines through openings: Windows. The shape shows the window type (single line: fixed, double line: openable).
• Hatched or shaded areas: Specific finishes, e.g., concrete (diagonal hatch), tiled areas, or new walls vs existing.

Reading dimensions

Dimensions in Australian residential plans are in millimetres. A 3500 x 4200 bedroom is 3.5m by 4.2m. Common minimum dimensions:

• Master bedroom: 4000 x 4500 minimum comfortable
• Secondary bedroom: 3000 x 3000 minimum
• Bathroom: 2400 x 2700 minimum
• Walk-in pantry: 1200 x 1800 minimum
• Kitchen island: 900 x 2700 minimum (longer for seating)

What is missing from most plans

Plans show layout, dimensions, openings. They typically do NOT show:

• How sunlight enters at different times of day (request shadow diagrams).
• Internal ceiling heights at different points (request a section).
• Door swing clearances (look for furniture conflict).
• Sightlines from one room to another (walk through mentally).

The walkthrough exercise

Stand in your hallway. Imagine walking the front door entry. Pretend it’s morning and you’re going from the master bedroom to the kitchen for coffee. Pretend it’s evening and you’re carrying a child to bed from the living room. Does the plan flow naturally for the routines you actually have?