How to Read Your Home Plan

Reading home plans when you're not an architect or a builder can be genuinely frustrating. Unless you work with drawings regularly, it's hard to know what they're telling you. So let's break it down, starting with what an architect's plan actually is.

What is an architect's plan?

An architect's plan is a graphic, technical representation of how a building is designed to look once it's built. It's drawn in two dimensions, and it sets out the various characteristics of a house or building across a set of drawings.

Why architect's plans matter

The importance of a good plan is hard to overstate. It answers the what, why and how of a construction project. It serves as a form of agreement between contractors, workers and clients. And it helps estimate the cost of materials and labour, and build a construction schedule.

The three types of view

There are three types of view used to present a structure in technical drawing.

Plan view. A bird's-eye view of the structure, drawn on a horizontal plane, looking down from above. There's a plan view for each floor, including foundations, basements and the roof.

Elevation view. Used to show the appearance of the exterior of the building, drawn on a vertical plane. It can also show the interior.

Section view. Also drawn on a vertical plane, a section view cuts through the building to reveal what's inside, the location of wall studs, insulation and other elements.

Reading the lines

One of the basic skills of reading a plan is knowing what each type of line means. A quick guide to the common ones:

• —Object line. The visible edge of a building element. Bold, and the thickest line on the plan.
• —Hidden line. Short dashes showing surfaces hidden from view in person.
• —Centre line. Alternating short and long dashes marking the central axis of an element.
• —Dimension line. Two solid lines with arrowheads pointing in opposite directions, showing the distance between two points.
• —Extension line. A short line at the end of a dimension line, showing the limit of the dimension.
• —Leader line. A fine line with an arrowhead, connecting a note or number to the element it refers to.
• —Phantom line. Long dashes alternating with short ones, showing how an element could be moved to an alternative position.
• —Cutting plane line. A line with arrows at each end, dissecting an element to display an interior feature.
• —Break line. Used to shorten long uniform elements and save drawing space.
• —Section line. Multiple short parallel diagonal lines, showing where the surface of an object has been cut in a section view.

Understanding the sheets

To keep a set of plans organised, standard letter codes are combined with page numbers:

• —G sheets. General sheets, the plan index, cover sheet, title block and plot plans.
• —A sheets. The architectural plans, floors, walls, ceilings and building sections.
• —S sheets. The structural engineering, foundations, roof structure and framing.
• —E sheets. The electrical plans, location and use of electrical fixtures, outlets and so on.
• —M sheets. The mechanical plans, ductwork, piping and control wiring.
• —P sheets. The plumbing plans.
• —Specification sheets. A detailed description of the materials used in construction.
• —Door, window and finish schedule. Information on the style, size and materials of doors, windows and finishes.

Four tips for reading a plan

1. 01Start with the title block. It displays the project name, plan number, drawing date and location, the basics you need before anything else.
2. 02Study the legend. The legend decodes the symbols used across the plan.
3. 03Check the scale and orientation. Found near the legend, this tells you the relationship between the size of the drawing and the size of the finished building.
4. 04Look for the architect's notes. Tricky parts of a plan are often explained in notes, attached separately or written directly on the drawing.

If you'd like your plans walked through in person, get in touch. We're always happy to explain.