architectural and interior design presentation

drawing to "scale"

If you have a brick that is 8" x 3 3/4" x 2 1/4" in actual size and you make a drawing of the brick that measures 8" x 3 3/4" x 2 1/4" you have made your drawing "full size." For small objects, full size drawings are OK. However, if you are drawing larger objects, like rooms and buildings, full size drawings are too big and are hard to use. Therefore, these types of larger objects are drawn at a fraction of their original size. This process is called "drawing to scale."

For example, you can draw objects "half size", where 6" on the drawing equals 1 foot (12") on the real object. If we were to draw the object one forth size, it would be at "the scale of" 3"=1' 0". The "scale" 1"=1' 0" is 1/12 actual size. If the drawing were done at the scale 1/2"=1' 0" it would be 1/24 actual size. And if it were drawn at 1/4"=1' 0" it would be 1/48 actual size. "One Inch", "One half Inch", and "One quarter Inch" are common architectural scales, as well as "One eighth Inch" scale.

For really large projects, smaller scales are used. The following is a list of scales used for very large projects:

1"=10 Ft. 1"=100 Ft.
1"=20 Ft. 1"=200 Ft.
1"=30 Ft. 1"=300 Ft.
1"=40 Ft. 1"=400 Ft.
1"=50 Ft. 1"=500 Ft.
1"=60 Ft. 1"=600 Ft.
1"=80 Ft. 1"=800 Ft.

In architectural use the major units of measurement are feet, inches, and fractions. When written, as in 12' 7 1/2", the feet are indicated by a single mark, similar to a prime mark, or 12'. Inches are indicated by two marks, or 7". If the dimension is an full number of feet (no inches), it is customary to indicate the distance as 12` 0". Fractions are added after the inch number but before the inch mark, or 12' 7 1/2". The hyphen is always present between the single footmark and the inch number.

A house which is 24 feet wide and 32 feet long would not fit on a piece of drafting paper unless it was drawn reduced in size. This reduction can be accomplished mathematically or with the use of an architect or engineer's scale.

For an example or two, we will use a scale listed as 1/4"=1' 0". 1/4"=1' 0" is an architect's scale because it is listed with a fraction equals 1' 0"; engineer's scales are listed as 1 equals a distance in ten foot increments, such as 1"=20' 0".

Find the 1/4" scale (as it is sometimes referred to) on the first of the two sample scales sheets, it is underlined and is the fifth scale down from FULL scale. Note that one foot at this scale would be drawn an actual length of 1/4 of an inch, or 1/4". Find the number 24 on the right side of this scale. This represents the 24' 0" distance (from the zero to the 24' mark) of the width of the example house. To find the 32' 0" scale distance, you must use the 16' mark and double the distance. You can now see how big the pencil drawing will be and can select a piece of paper accordingly.

Notice the 24' marks on the two scales above the 1/4"=1' 0" scale. The distances are shorter from the zero to the 24' mark and will give a pencil drawing smaller in size than the 1/4" scale. The scales under the 1/4" scale will give a pencil drawing larger than our sample 1/4" scale. All these other scales are labeled with their fractional names.

Say the building we needed to draw was not 24' 0" x 32' 0", but 100' x 200'. At 1/4"=1' 0" the pencil drawing would be very large (you would need a piece of paper at least 25" x 30"). That is why the other scales above the 1/4" scale are used; to reduce our pencil drawing to a nice size. The size must be small enough to fit the drawing onto the paper, but also the size must be large enough to fit all the furniture, notes, dimensions, etc. into the drawing. There are times that you would want a drawing to be drawn in a larger scale to show a tradesman how to specifically build a small portion of a building, this is known as a detail. Details are drawn in 3/4", 1", 1 1/2", and 3"=1' 0" scales.

Mathematically you must realize that each one quarter inch represents one foot at 1/4" scale. 100 feet would be represented by 100 one quarter inch spaces (100 times 1/4") or 25". Similarly the 120 feet would be represented by 120 one quarter inch spaces (120 times 1/4") or 30". 1/8"=1' 0" scale uses one eighth spaces, 3/4"=1' 0" scale uses three quarter spaces, and so on. In order to avoid calculating each dimension, an architect's scale is used which gives direct proportional readings in several accurate scales. The length of every foot in the actual building is reduced to a constant fraction so that all of the parts of the building are in exact relationship to each other.

Architect's scales are calibrated into feet and inches in standard sizes (1/16"=1' 0" through 3"=1' 0") so that large drawings, details, renderings, and models can be conveniently drawn and constructed in manageable sizes.

In order to read measurements which are less than one foot on the 1/4" scale, it is necessary to use the space to the left of the line marked zero. This space is divided into twelve parts, each representing one inch. I have put marks at the 5" and 10" designations. Find the 5" mark on the 3/8"=1' 0" scale to see it a bit better. These spaces representing parts of a foot are sometimes divided into only four or six parts, designating 3 inches or 2 inches to scale. If it were divided into twelve parts, the spaces would be so small that they would be difficult to distinguish. Other scales are divided into twelve parts besides the 1/4" scale. Still other scales are each divided again into half spaces and quarter spaces designating one half and one quarter inch measurements. Look at the 3/4" and 1 1/2" scales as an example.

Civil engineer's scales are always recorded in feet and decimal parts of a foot, rather than in feet and inches. This is because engineers are dealing in calculations more than architectural spaces, and it is easier to multiply and divide decimals than fractions. The one inch unit on the 1"=10' scale would have 10 divisions, and the inch unit on the 1"=20' scale would have 20 divisions. If a scale of 1"=100' were needed, the 1"=10' scale could be used by merely letting each small unit represent 10' instead of 1'. This method applies to other scales as well.

One very important thing to remember about scales and scaling is that the scale can be used only on the original drawing itself, not on a print or copy of a drawing. Any measured or scaled dimensions on a print can be only approximate. Paper shrinkage, caused by the varying moisture content or heat of the printing proceed, can result in a line measurement that is off as much as two inches at 1/4"=1' 0". This is why it is a poor practice to scale a print, rely instead on the written dimensions given in a print. This is very important in actual construction or in redrawing a drawing without the original present.