Drawing 2D: Projection and Section

What is 2D architectural drawing

Architectural drawings are essentially two-dimensional projections or sections of three-dimensional objects. All of these are parallel views, meaning that the viewing lines are all parallel. This makes it easier to construct them and measure distances between various elements in the drawing.

Projection: Most common projections are elevations and master plans. Elevations are just views from outside which show facades of the building; Masterplan is the top view of a large range of buildings and the environment.

Section: Plans are in fact horizontal sections of a building with the view towards the floor. Sections are in general vertical sections of the building which show relationships between different floors.  there are usually four of them.

Additionally, to these, other projections like for example axonometry show the building from different angles.

Section drawings

Plan

1. The horizontal section of a plan is usually 1.2 m above the floor surface.
2. Draw axis and columns (if there are any).
3. Draw centerlines of walls.
4. Recognize which lines are cutting line and which lines are viewing line. Then offset the centerline according to the thickness of the wall. Cutting lines are thicker than viewing lines.
5. Add windows. The wall line of the cut window is the viewing line, and the glass line is the section line. There are several methods of drawing the window. The window higher than the section surface could be marked by dashed lines.
6. Add furniture and stairs.
7. Add text and height marks.

Section

1. Draw the section cutting line on the plan, and rotate the plan to the direction that matches the section. Note the direction of section mark: The section mark is generally composed of one long line and one smaller line, they are mirrored to both sides of the building plan. The longer line indicates the position of the cutting plane, the shorter line shows the direction of observation.
2. Add the reference lines according to the plan.
3. Draw centerlines of walls and floors.
4. Recognize which lines are cutting lines and which are viewing lines, then offset them.
5. Add windows, furniture and stairs.
6. Add text and height marks, the style of the height marks is the same as elevation drawings.

Projection drawings

Elevation

Notice that we handle drawing an elevation without a 3D model.

Workflow is similar to section drawings.

1. Choose the drawing facade.
2. According to the plan, draw reference lines along with the turning point of the elevation.
3. Mark the height line for each part of the elevation.
4. Draw the overall shape of the facade, do not forget the component behind the cutout part.
5. Add windows, doors, glass frames, and other details such as material texture if needed.
6. Add shadow if needed.
7. Mark the height on one side of the building. The elevation mark is a downward-facing triangle with height data marked on the extension line of its upper edge.

Master plan

1. Choose drawing range.
2. Add map building outlines, roads, contours, trees,  and other needed details. The detailed content of the drawing depends on the purpose of the drawing. Construction drawing requires very detailed information, while other drawings may only emphasize the important information for the design. Masterplans of some cities are public resources (such as Helsinki map) that could be download online.
3. Mark the project. There are many ways to address your building (or area), such as shade the roof, add shadow to the designed area, draw the outline of the building, etc.
4. Add additional information, such as compass, scale, material mark, text, etc. Additional information also depends on the purpose of the drawing. Sometimes the master plan is combined with the overall description. The most important thing is to determine what the drawing wants to express.

Chapters

I Digital Drafting Basics

II Drawing 2D: Section and Projection

III Drawing 3D: Axonometry

IV Drawing 3D: Perspective Section