|An architectural section is subset of orthographic projection drawings wherein the projection plane is positioned intersecting the objects or space of interest. Objects are depicted according to their relationship to this (typically vertical) 'cut plane'. Sections can reveal the interior composition of wall systems, the interrelation of adjacent spaces, and the relationship between a building and its surrounding context.|
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A special case of parallel projection , and more specifically a type of orthographic projection, a section may be conceptualized as a (typically vertical) cut through an object or building. Most aspects of an architectural section drawing closely follow the conventions of orthographic projection, while others aspects (such as the way the interior of walls and roofs are depicted) are notational.
This drawing depict spaces inside and outside a building. Context for the surrounding spaces (trees, buildings) as well as people (silhouettes) are often included to help visualize the space. Typical Scale: 1/8"=1' to 3/8"=1'.
This section explains the construction systems and material choices by isolating just the wall, floor, and ceiling attachments on one side of the building. Wall sections detail the foundations, interior and exterior surface material thickness, and wall composition. Typical Scale: 1/2"=1' to 1"=1'
This is a vertical cut through the context of the surrounding site, which may include other buildings, trees, water, or other landscape features to explain the nearby adjacencies.
A partial or call-out section magnifies the scale of a small portion of a larger section in order to show more highly detailed information. These drawings typically range from 1" = 1' to full scale.
A section perspective is a composite drawing which combines a section through the building, room or detail, with the perspective view that would appear beyond that cut. Not generally used in actual documentation, they are a valuable tool for presentation drawings and process and study work. They are good at illustrating the project narrative (much like a rendering) and, in place of conventional section, they may be more dynamic in conveying the relationship between spaces.
Conventions of Line Weight and Type
Line weight , or the visual lightness or darkness and width of a line, are conventionally employed in section drawings as follows:
Elements which intersect the cut plane of the section are demarcated by the heaviest line weight, by a hatch or with poche.
The middle line weight is used to show physical objects that are shown in elevation beyond the cut. This may include wall edges, doors, windows, etc.
The lightest line weight represents material, finish or texture on physical objects in elevation. It can also be used to context or building elements that are far beyond the section cut.
Dashed lines in section represent objects that are not 'visible' in that cut, either lying behind the cut plane or obscured by other elements, but may be important to show.
Dashed lines at different spacing, or dotted lines can be used to show range of motion for operable components or to represent other non physical phenomena such as light throw from openings and fixtures or sight lines from various locations in the space.
Section drawings may contain several other line weights as well, depending on the depth you want to convey. Major cuts, through shear walls or other large built components may be in a dark poche , whereas cuts through smaller interior elements may be of a slightly lighter line weight or lighter poche .
Where to Cut a Section
Where NOT to Cut a Section
There are a number of online resources that document the process of constructing plan drawings.
- How to Draw a Wall Section
- This is a helpful introduction video to Wall Sections that clearly explains the role it plays in the construction process.