Blueprint Reading & Layout Flashcards

A site plan shows a contour line labeled 98.5 and the next line labeled 99.0. What does the difference in elevation between these lines represent?

Answer: 0.5 m vertical change in terrain

Contour lines connect points of equal elevation. The difference between adjacent contour lines (0.5 m in this case) is the contour interval — it represents 0.5 metres of vertical change in the terrain.

What drawing symbol indicates 'not to scale' (NTS) and when is it used?

Answer: A note reading 'NTS' placed near the detail, used when a drawing is schematic or diagrammatic

NTS (Not to Scale) is a written notation placed near a detail or dimension when the drawn image is schematic, conceptual, or distorted for clarity. Dimensions still apply — only the visual proportions may be inaccurate.

On a framing plan, what does 'BM' typically abbreviate?

Answer: Beam

On framing plans and structural drawings, 'BM' is the standard abbreviation for Beam. The drawing legend should always be checked, but beam is the most common usage in structural framing contexts.

What is the purpose of a revision cloud on a construction drawing?

Answer: To highlight areas of the drawing that have been changed since the previous issue

A revision cloud is a series of arcs forming a cloud-like shape drawn around areas that have been modified. It is paired with a revision triangle and number/date to track what changed and when.

A floor plan specifies a partition wall with the note 'STC 50'. What does STC refer to?

Answer: Sound Transmission Class — a rating of how well the wall blocks sound

STC (Sound Transmission Class) is a single-number rating measuring a wall assembly's ability to block airborne sound. STC 50 means speech is barely audible or inaudible through the wall. The National Building Code references STC minimums for party walls.

When a drawing shows 'EQ' between two dimensions, what does it mean?

Answer: The spaces are equal — divide the total evenly

'EQ' means Equal — the space or dimension is to be divided equally without specifying individual measurements. For example, three studs with 'EQ' spacing means divide the total length into three equal spaces.