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4.0.0 PRELIMINARY (PENCIL) DRAWINGS

4.1.0  Applications of the various scales, and choosing the proper one
4.2.0  Sheet Layout
4.3.0  Procedure for preliminary plan drawings
4.4.0  Procedure for preliminary elevation drawings
4.5.0  Procedure for preliminary section drawings
4.6.0  Procedure for preliminary detail drawings
4.7.0 Paraline or "axonometric" drawings

4.0.0 PRELIMINARY (PENCIL) DRAWINGS

4.0.1 Preliminary drawings provide the means to identify and correct errors in measuring.  Once drawing has begun, errors in wall alignment, window placement, roof heights, for example, quickly become apparent, especially when plans are overlaid, elevations are matched with adjacent elevations and corresponding sections, etc.  Corrections are of course more easily made on pencillings than on ink drawings. 

4.0.2 A number of factors may contribute to the misalignment of drawings.  Plans will not line up if walls are not plumb; this is especially true if roof weight is causing walls to spread apart.  Adjacent elevations will not align if, for example, the end point of an eave line is visible on one elevation, but on the adjacent elevation the eave line is hidden by a gutter and not measured.  Also, improperly established or recorded datum lines and the use of different brands of measuring devices and drawing scales lead to mismatches.  Finally, variations in temperature and humidity cause vellum to change shape and size, so drafting film is recommended when highly accurate preliminaries are required.

4.1.1  At the outset of the project, the choice of scales for final drawings (as well as the level of detail required in field notes) is made according to the following criteria:

1.  Level of detail, amount of graphic and notational information required for the set.

2.  Size of the structures to be drawn.

3.  Available time and financial resources.

4.  Final sheet composition, compatibility with other sheets in a set.

4.1.2 In the foreseeable future, the metric system may replace the English system in architectural practice, as it already has in the sciences and such disciplines as archaeology. 

Although buildings designed in the English system should be recorded as such, prehistoric structures and sites should employ the metric system.  The basic units of both systems are presented in 15.0.0 Appendix G: English and Metric Systems.

4.1.3 Metric architectural scales.  The ratios represent centimeters to centimeters.
 

4.1.4  English System Architectural Scales¹
 

4.1.5  Drawings produced at larger scales display the highest degrees of accuracy, and can be the most aesthetically pleasing of HABS existing-condition drawings.  Measurements are obtained by hand and by using profile combs, rubbings and careful photography.  (Photographs must be taken with the camera film plane parallel to the picture plane of the object.  The delineator should note that 35 mm camera lenses and enlargement on photocopiers introduce degrees of distortion.  Hand measurement should be used for verification.)

Drawings at full scale may use texturing (stippling) to emphasize curvatures and the three-dimensional quality of bas-reliefs and other ornamentation.  This technique can be used very successfully in delineating carved wood, stone and cast plaster.

4.1.6  Mixing of scales among plans, elevations and sections is generally not recommended.  However, if it has been determined that, for example, that simple, repetitive plans of a very large structure can be drawn at 1/8" = 1'-0", but the elevations and sections need to display more detail, they should be drawn at 1/4" = 1'-0".  A corresponding increase from 3/16" = 1'-0" is to 3/8" = 1'-0". 

4.2.0 SHEET LAYOUT

4.2.1  A number of aesthetic and informational considerations should be kept in mind when laying out individual sheets of drawings.  The future use of the drawings--as determined by clients and communicated to project leaders--will determine the character and level of information to be imparted by the drawings. 

4.2.2  Drawings to be used by future restorers, adaptive reusers and preservation/maintenance workers will require thorough dimensioning, material and construction notes, and sufficient room on which these future users can make their own notations.  Drawings from the first half of this century--especially detail sheets--tend to condense a great deal of information.  Such sheets can be artistically exquisite compositions and suitable for exhibition and publication.  Sheet density is to be considered because drawings are later reduced for publication, portfolios, and transmission to the Library of Congress.

4.2.3  Some or all of the following items will add to the "size" of most drawings, and should be factored into sheet lay-out:  titles, dimensions, scales, north arrows, materials and planting lists, plan keys, areas dashed-in for reference such as roof lines and basements, details, reconstructions based on measured remains, and exploded views.

4.2.4  When more than one drawing is to appear on a sheet, the combination must enhance comprehension of the structure.  One should avoid completing a half-filled sheet with a drawing that cannot be referenced to its companion on the sheet.  The most common combinations are plan/plan, elevation/section, elevation/plan, elevation/detail.  (See Figure 4.10)

4.2.5  Drawings of sites and structures requiring match lines are often reduced to photographic negatives, then spliced together to produce composite plans, elevations, etc.  These drawings must be rendered with the utmost precision and consistency of line weight and texturing.  When drawing large site plans, one must plan match line cuts around, rather than through buildings, in order to facilitate splicing.

In addition to graphic scales and north arrows, site plans will often include planting lists, structure lists, historical and other descriptive notes, and vicinity and location maps.  Planning the sheet composition will include obtaining over-all site dimensions early in the project in order to choose a graphic scale. 

4.2.6  Elevations of more than one but less than two sheet lengths may be drawn on one sheet with match lines.  Another possible technique is to combine sections and elevations running continuously across two or more sheets. 

4.2.7  Title sheets generally include a location map, a statement of significance, and a project information statement.  In addition, title sheets often display rendered, drafted or photographically transferred images which represent the project. 

A statement of significance describes the architectural and/or historical importance of the project.  It is prepared by the project architectural supervisor or historian, and is then submitted to the HABS Washington office for review before inking.  It should be carefully proofread for grammatical, spelling and factual errors.

It is the responsibility of the project supervisor to compose a project information statement that briefly describes the conditions under which the documentation was carried out.  Credit should be given to sponsors and participants--including their titles and professional or academic affiliations.  This statement must also be approved by the Washington office. 

For HABS projects, texts are composed, typed with justification at the desired column width on a word processor, at a font size equivalent to the mechanical lettering template to be used (18-point type for 175 Leroy template.)  The printed text is then laid under the drafting film for tracing with ink.

4.2.8  Site plans are either incorporated into title sheets or drawn by themselves, depending on the site's extent and significance.  At a minimum, documentation will include the following information: 

1)  buildings designated by roof plan, and called out or
isted in a key; 

2)  trees showing trunk diameter at breast height and canopy, called out by abbreviations and listed  by common and botanical names;

3)  other significant plants, similarly identified;

4)  walls, fences, sculptural elements, street furniture, retaining walls, paving, utility poles; 

5)  water features;

6)  title, graphic scale, north arrow.

4.3.0 PROCEDURE FOR PRELIMINARY DRAWINGS

1)  Locate the appropriate reference points:  plan boxes and individual points from which to begin placing the exterior walls through triangulation.  Triangulated points are located by adjusting a compass to the desired distances on a scale, then drawing intersecting arcs;

2)  using wall thicknesses, locate the major lines of the interior spaces;

3)  complete interior space configurations by checking their diagonal measurements;

4)  overlay plans of other levels to check for plumbness of walls
nd general accuracy;

5)  complete door and window frames;

6)  complete remaining features (hearths, floor tiles), locate appropriate appliances and fixtures;

7)  mark points for dashed lines, floor boards and other simple, repetitive patterns;

8)  mark points for dimension lines.

Figure 4.2:  Layout of a second floor plan, Keeper's Quarters (East House), Devil's Island Light Station, Apostle Island National Lakeshore, Bayfield, Wisconsin.

4.4.0 PROCEDURE FOR PRELIMINARY ELEVATION DRAWINGS

Figure 4.3:  Layout of foreshortened elevation elements.
(left) Scotty's Castle, Death Valley National Monument, California;
(right) George W. Eckhart House, Wheeling, West Virginia.

1)  draw horizontal datum lines, preferably with a .19 mm (4x0) pen in order to maintain a thin, accurate line;

2)  if exterior walls, columns, etc. are not plumb, draw vertical datums as needed;

3)  draw major walls and roof lines, and other vertical and horizontal elements;

4)  draw major openings;

5)  project foreshortened elements  from plans (bay windows, spiral stairs, cylindrical structures), other elements angling or curving away from drawing plane (Figure 4.3);

6)  locate dashed elements (basements, hidden lines, removals for graphic clarity);

7)  locate marks for inking of siding, roof materials;

8)  create templates for repeating elements;

9)  notate areas to receive special treatment, such as stippling or other freehand techniques.

1)  clearly demarcate the section cut on the plan(s), making sure that it will be logical, illustrative of spatial relationships, and easily understood;

2)  copy the wall locations from the plan;

3)  if the wall planes are consistent between the section cut and the elevation it faces, trace the outline from that elevation;

4)  to minimize confusion between elements close to the drawing plane and those far behind it, draw the section on separate sheets as a series of slices through the structure, the closest being the actual section cut, and the farther ones serving as interior elevations; this technique is particularly useful for large, columned spaces such as barns (see Figure 3.17 and Figure 3.18);

5)  complete interior elevations, grade line, exterior elevation if applicable.

Figure 4.5:  Au Sable Light Station. 
Pictured Rocks National Lakeshore, Alger County, Michigan.

4.6.0 PROCEDURE FOR PRELIMINARY DETAIL DRAWINGS

1)  Determine the location of the detail in the set (title sheet, detail sheet); this will help determine the scale at which it is to be drawn; 

2)  in the case of window and door details, determine the layout of their components (interior/exterior elevation, plan, section);

3)  determine strategies for penciling and inking:  whether the final drawing will be traced from a photograph, drawn freehand, or from measurements; the type of texturing to be used to show grain and curvature; level of abstraction, and, if necessary, shading.

Figure 4.6:  A: Wooden finial, 
shaded to emphasis roundness.
 

Figure  4.7:  Various detail drawings.
B: Carved stone capital, partially traced from photograph.
C: Concrete aggregate baluster.
D: Glazed terra cotta tile, drawn from rubbing.
 

Figure 4.8:  Typical treatments of window and door details.

These are useful in presenting structural information, especially of larger buildings with complex combinations of columns and truss work.  These drawings impart a feeling for the mass and volume of the building without the distortion of essentially unmeasurable perspective renderings.  Axonometrics are also extremely useful in illustrating mechanical processes and industrial layouts.  Measurements obtained for plans, elevations and sections will be used to produce axonometrics.

4.7.1  There are six basic types of axonometric drawing:  30º oblique, 45º oblique, 45º dimetric (rotated plan, 15º dimetric, isometric (30º dimetric), and trimetric (rotated plan).  Refer to Figure 4.9 in order to choose the type which will best illustrate massing, roof framing, interior structure, etc. 

4.7.2  Procedure for preliminary axonometric drawings:

1)  Choose between an exploded or unexploded view, depending on the potential usefulness of each;

2)  determine the scale and size of final drawing BEFORE beginning its construction;

3)  determine the amount of structure to be revealed, and what kind of peel-away technique will be used;

4)  begin the construction by drawing the base line which represents the picture plane;

5)  using an adjustable triangle, construct the angles for the base lines of the drawing;

6)  when laying out the measured lines, always hold the architect's scale against the parallel bar and against triangles braced by the parallel bar. 

Figure 4.9:  Generating axonometric drawings.  HABS delineators usually employ the isometric (30º dimetric).  Charles G. Ramsey, 
Architectural Graphic Standards, 8th Ed., page 797.

Figure 4.10:  Proper sheet lay out for plans and elevations.