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Al Whitley/3 min read

Understanding the Basement Plan Scale and Building Size Ratios

Blueprint Reading Essentials

Title Block

Project name, scale, date, drawing number.

Plan Views

Top-down view of each floor — walls, doors, windows.

Elevations & Sections

Vertical views and cuts revealing wall and floor construction.

Detail Drawings

Zoomed-in views of specific construction conditions.

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This tutorial walks through understanding the basement plan scale and building size ratios, covering essential tools and techniques for your projects.

Hello, let's continue on. You can see that I am back on the basement plan. And again, we have our A2.2 sheet.

We have our revision information. We have our keynotes. We have the bubbles that are in this area that are saying that we made modifications to the drawing with the delta number that reflects back on the revision date.

We have our notes in this area. We have our legend, which is showing us information such as wall types and so on and so forth. And again, we're showing the solid walls as our continuous studs.

We have our masonry walls with the hashes through them. We have our net pattern over here for the double stud walls. If I zoom into the bottom right, you can see that I'm showing it's the lower floor plan.

You can see that the scale is 3/16 of an inch. Now, this is relatively unusual to have scales such as 3/16 of an inch. But we had some requirements.

The requirements were we had to fit the building on a 22" × 34" sheet of paper. The building would have been too big to fit on the drawing at 1/4 of an inch. It would have shown too small if we'd said 1/8 of an inch.

We used 3/16 of an inch, which is halfway between 1/4 of an inch and 1/8 of an inch. And let's just talk about scale again. That if I have a drawing that's 1/4 of an inch represents a foot, that means that when I print the drawings one to one, that 1/4 of an inch represents 12 inches, which means that 1/4 of an inch represents a foot.

So, the building at 1/4 of an inch equals a foot. So, 1/4 of an inch is to 12. We cross multiply, we get 1 to 48, meaning a building that is drawn at 1/4 of an inch equals a foot is 1/48 of real size when printed on a piece of paper.

So, 1/4 of an inch equals a foot means a 1/4 of an inch represents 12 inches, which means that one inch represents four feet. So that's 1/4 inch. A 1/8 of an inch means a 1/8 of an inch represents a foot.

So, an eighth is to 12,1 is to 96. So again, a 1/4-inch drawing shows a building at 1/48 of real size. A 1/8-inch drawing represents a building at 1/96 of real size.

And so we're halfway in between.