The following list of architectural dimensioning standards ...

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The following list of architectural dimensioning standards is taken from “Architectural Working Drawings”, by Ralph W. Liebing and Mini Ford Paul (Wiley - Interscience, 1983).

Dimensions, Notes and Titles

Dimensions, notes and titles contribute a great deal to the complexity of a drawing.

Notes and dimensions should not be placed in a haphazard manner merely to fill gaps; they must be done in a methodical way and with due thought given to their placement and extent.

Dimensions:

The purpose of dimensioning is to define size and location of the various materials and components.

1. Dimensions should be read across the sheet and are usually placed at the bottom; vertical dimensions must be readable from the right-hand edge.

2. Dimension lines should be set apart from object lines by spacing and line weight so that the chance of their being mistaken becomes minimal; extension lines are taken perpendicularly from the building lines out to the dimension lines. Extension and dimension lines should be kept light in value but should have enough line weight to reproduce in their entirety.

3. All dimensions are placed above the dimension lines and should always be given in feet and inches; the exception to this rule applies to dimensions of less than 12 inches. The draftsperson must decide whether to use 12 inches or the symbols for feet and inches (12” or 1’-0”). Anything larger should be referred to in feet and inches.

4. Fractions should be shown with a diagonal slash by which the numbers are separated for greater clarity.

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5. There are usually three dimension lines: the line closest to the building should describe its small elements - for example, piers, door widths, and window openings; the second line should carry some of the small dimensions and reflect major features such as a wing, section or offset; the third line (farthest from the building line) should be an overall dimension that will show the total distance from outside face to outside face of the building. Various types of construction will demand slight changes in dimensioning; for instance, wood frame dimensioned from face of stud to face of stud.

6. In surveys, site plans, or other engineering-oriented drawings, dimensions may be shown in feet and decimal parts of a foot, usually carried to two places; for example, one foot and seven inches would appear as one point five eight feet (1’-7” = 1.58’).

7. Dimension lines should be defined by an arrowhead or some other symbol. The arrowhead or other designator should point to an exact extension line. Dimensions are definite measurements from one point to another.

8. Similar dimensions or the same dimensions may be required several times on different drawings. Similar dimensions should, however, never be duplicated on the same drawing. Needless repetition should be avoided.

9. The clarity of the drawing can be improved if extension and dimension lines do not cross. In some instances crossed lines cannot be prevented, but placement should be made with the greatest care possible to obviate confusion.

10. Dimensioning of architectural drawings involves actual sizes, regardless of the scale employed. A note may contradict the dimension given; for example, a 2x4 stud may show a measurement of one and one-half inches (1 ½”) by three and one-half inches (3 ½”).

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11. Obvious dimensions may sometimes be eliminated. A door place in a narrow hallway does not necessarily have to be dimensioned, the inference being that the door will be centered.

12. To avoid needless dimensions or crowding, door and window sizes are often eliminated by the use of marks and a scheduling system; The contractor can then apply the correct size to any given location.

13. Beams and columns are located by their centerlines. A column, for instance, would have a centerline running in both directions.

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14. To increase legibility, identical units, spaces, or solids should be dimensioned at one element of the series, and by a note in a specific area should be shown as repetitive. This will eliminate the need to repeat each unit from start to finish of the series. The limits of any series should be marked by showing their extension and dimension lines and arrowhead designators.

14. The dimensional system cannot be left hanging in limbo; it must be tied to tangible usable items apparent in the construction. The building line, or perimeter of the structure, can be used for this purpose. Items are often referenced one to another.

Notes:

1. Notes and dimensions must be planned together so that one will not obscure or interfere with the other.

2. Long leader lines between notes and their points of application should be avoided.

3. Notes can be placed inside dimension lines; that is to say, between the dimensions and the object drawn.

4. Notional items include room names, identification of materials, reference marks for schedules, and titles. They may also show specific locations or references.

5. It is a good idea to group notes around the construction to which they refer. For instance, in a wall section, all notes that have reference to the floor slab should be placed in one general area close to that section; notes that apply to the wall construction above the slab should be grouped elsewhere to avoid being mistaken or interchanged.

6. Notes can sometimes be placed close together. The spacing between the notes must be greater than the spacing between individual lines. The minimum should be a full line height or half the height of the lettering.

7. For better readability and neatness, notes can be aligned at the left to present an even margin. Notes can also be staggered along a slanted imaginary line.

8. Notes should be as close to the point of application as possible; for example, the topmost note directed to the floor slab should describe the topmost material in the floor slab construction, and so on down the line. This will result in an uncomplicated system of leader lines.

9. Leader lines may be drawn freehand in sweeping curves or drafted in some sort of angle.

10. Leader lines should point away from the first or last line of a given note, never from the center, and should connect with the material to which it refers.

11. When notes contain nomenclature, it is important that the same terminology be used throughout. What appears on the plans should appear on the elevations, wall sections, and so on. All drawings should agree - most of all with the specifications.

12. Some notes of instruction are often necessary; they will let the builder know that a certain condition must be met - “Match existing wall construction”.

13. A note can also clarify intention; a good example is “slope floor to drain”.

14. Notes should always be concisely phrased to make a point that could be difficult and cumbersome to display in a drawing.

15. It is important that each space be identified with name or number for specific purposes such as scheduling or reference.

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