How to Read an Architectural Scale

If you'd like to look like a pro at a building committee meeting, or would just like to know how to read an architectural scale for your own gratification, this simple how-to will show you how.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Architectural Scale
• Set of Building Plans

1. An architectural scale is roughly 12" long and has 6 different faces - two on each side of the scale. Each face has two scale factors, with the exception of the normal inch scale which reads from 0 - 12." With 3 sides and 6 total faces, you end up with 10 different scales plus the 1:1 scale.

2. If you lay the architectural scale on a flat surface and look at it, you will see the scaling factor at the left end of each face. If you see the fraction 1/8, that means that that 1/8 inch on the scale stands for 1' on a plan.

3. Each face on a side reads in opposite directions. For example, 1/8 and 1/4 may share a "face" on your architectural scale - with a face being half of a side. The 1/8 scale reads from left to right and the 1/4 scale reads from right to left.

4. People are often confused by the double numbers on each face of a scale, don't be! Let's use the 1/4 and 1/8 scales as an example. If you start at the left and look at the 1/8 scale, you will notice that the 0 is set slightly higher. As you read from left to right, all the numbers that are associates with the 1/8 scale are also set higher. When you read the scale using the 1/8 face, you can disregard all the number that are set lower because are used with the 1/4 scale.

5. Look at your scale again and know that each number that pertains to a scale represents feet. Again looking at the 1/8 scale, the numbers that you will see go up by 4's - 4, 8, 12, etc. Each of these numbers represent that many feet.

6. You will also notice small lines to the left or right of the 0 on each scale. Those lines each represent an increment of a foot. Using the 1/8 architectural scale again, you will see 7 lines with 6 total spaces in between them. Each of these spaces represents 2".

7. 
   Use Scale to Read Building Plans

   Now, get a set of building plans. See if a scale is listed. For example, it may say scale: 1/8" = 1' - 0". In this case, you know you can use your 1/8 scale. To look at dimensions on a plan, simply set your architectural plan down on the plan and measure the distance using your 1/8 scale.

8. If you have a set of building plans, but no scale is shown on them, you can figure out which scale to use if you know the dimension of anything on a building plan. For example, if you know a room is 10' X 12', you can simply set your scale down on the section that is supposed to be 10' and check it against the faces of your scale to see which scale matches with the 10' known dimension.

Tips & Warnings

• Here is a guideline showing how architects normally use scales:
• 3/32 and 3/16 faces: Floor Plans, elevations, roof plans
• 1/8 and 1/4: Seldom used for floor plans, foundations, exterior elevations, building sections, and mechanical
• 3/8 and 3/4: Sometimes used for same things as 1/8 and 1/4, but very infrequently
• 1/2 or 1" face: Sometimes used for large scale floor plans or blown up areas within a floor plan, also used for small details within a plan
• 1.5/3: This is used exclusively for small details

[mizchulita]

on 12/27/2008 This is an awesome article. I want to build a straw bale house, and you can buy plans online. Now I can read them!