Drafting for Interior Design

The proportional scale doesn’t get much mention in drafting classes, but it’s a handy tool.  With it, you can enlarge or reduce a picture by a specific percentage. Examples of uses: to copy/reduce a photo to fit in a mat, or copy/enlarge a drawing to use in a floor plan or other architectural drawing.

The scale has a small wheel on top of a large wheel. To enlarge a 10” tall drawing to 14” tall, spin the small wheel until its 10” (the “before” size) mark lines up with the outer wheel’s 14” mark (the “after” size). The center window then shows the percentage needed to enlarge (in this case, 140%). Set the copy machine’s zoom feature to that percentage. 

The drawing you’re enlarging/reducing doesn’t have to have a known scale. Just draw a line across its length, and measure that line in inches. That’s the “before” size.

Read about the proportional scale in my book,  Architectural Drafting for Interior Designers

Beginning drafters, this is how to draw a straight line. Use a parallel bar! To draw a straight vertical line, rest a triangle directly on the parallel bar. DON’T do this:

This “eyeballing” will not result in a straight line, much less parallel straight lines.

Photos from my book, Architectural Drafting for Interior Designers.

This photo shows drafting and clutch pencils. The drafting pencils are on the right. They come in .03, .05, .07 and .09 mm sizes (the size of the hole at the tip). They’re filled with sticks of graphite that come in different degrees of hard and softness (light and dark). It’s good practice to keep a .07 filled with a dark lead (such as HB) and a .05 filled with a light lead (such as 4H), to maintain a strong contrast between object and construction lines. Clutch holders are for 2 mm size leads, which are sharpened in a lead pointer (stick the pencil in it and rotate) or by rubbing on a sandpaper block. While a greater variety of pencil strokes can be obtained with them, the constant sharpening they require is tedious. The smaller drafting pencils work just fine. Don’t confuse them with the very cheap mechanical pencils bought in a pack for a dollar, though. The difference is in the design at the tip. You will get better drafting results with a bona fide drafting pencil.

Read more in my book, Architectural Drafting for Interior Designers.

These drawings, from my book Architectural Drafting for Interior Designers, show how to draw multiple parallel, angled lines using two triangles. This technique also works to draw perpendicular lines. Handy for when you don’t have an adjustable triangle.

Align a triangle with the line you wish to draw lines parallel to. In this case, the line is the wall the door is on.

Brace the triangle with a second triangle. You can also brace it with a scale.

Slide the first triangle back and forth on the second one to draw parallel lines. Or to draw lines perpendicular to the line the first triangle was aligned with.

You need the right tools to do the job! This photo, from my book Architectural Drafting for Interior Designers, shows most of what you’ll need to do a drafting project. Your instructor will have personal preferences, such as as French curve instead of the flexible curve.

If your college doesn’t sell tools bundled as a kit, online stores sell them at competitive prices. I like utrecht.com and cheapjoes.com.