How to Read a Drawing Plan With Details

Establish a drawings orientation relative to its proposed site -- if at the construction site, turning the drawing in your hands to orientate it with the actual construction may make it easier to identify some of the elements on the drawing that have already been constructed. Look for any legends or keys on the drawing that may explain how certain elements are represented in terms of hatching patterns and line weights.

Identify key elements of a drawing; start with the walls, which are normally the most prominent elements. Move around the building's perimeter to see if you are able to identify door openings, which are often indicated by a quarter circle adjacent to the door; this indicates the door's swing. Similarly, look for window openings within the plane of the wall and see if you can identify the box rectangular window frames and line between them to represent glass. Look for the cavity insulation within the plane of the wall; it usually has a distinctive hatched pattern.

Develop the mindset of imagining how something would look if you were to cut through it. For instance, a door when viewed in plan will appear as an elongated rectangle; a window frame as a small rectangle at its simplest, or a more elaborate rectilinear shape at a larger scale where drawings show greater detail. Cut timber stud frames are often indicated by a rectangle with a cross in them; metal studs are indicated differently, often indicating the cut profile of the metal.

Look for columns and posts, which often stand alone and away from walls. You may see lines indicating a grid between them. Steel columns are relatively easy to identify because they appear as the shape of the letter H for a regular steel column, and as a square with rounded edges for a hollow steel section. Building structure is also usually identified with a bolder line weight. Pipes that travel vertically through the building may be seen as circles; sanitary pipes are normally indicated in the corners of rooms -- often boxed in a duct for concealment.

Look at larger scale drawings that show greater detail and how components interface with one another. Look for primary elements first, such as walls and columns, then work down to smaller elements such as doors, windows, insulation, ties and membranes. If you are unable to understand something on a small scale drawing, try looking at a larger scale drawing -- they normally have greater detail.