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Lesson 1.1 Construction Prints for Buildings

A set of construction prints (also called working drawings, or a set of plans) consists of all drawings necessary for the carpenter to construct a building. The set is composed of plan views (called plans), elevation views (called elevations), and detailed drawings (called sections and details); a schedule of drawings; and notes and information (called specifications). Specifications consist of information such as the quality and quantity of the materials and the construction methods to be used. A well-drawn set of prints and well-written specifications will help prevent disagreements and misunderstandings.

The purpose of construction prints is to be exact about shape and size. They are generally scale-size (with dimensions). It is very important to know how to read and use construction prints.

1-1. Information on Drawings

Drawings contain different lines, scales, and symbols. To read drawings, you must be able to interpret these items. They also include other information in the form of schedules, notes, and tables.

Schedule of Drawings. A schedule of drawings lists the drawings by number, title, and sheet number (Table 1-1). It is usually on the first drawing of a set of prints.

Table 1-1. Schedule of drawings

General Notes. General notes give additional information that is needed (Figure 1-1). For example, item number 3 is for the carpenter.

Figure 1-1. General notes

Graphic and Ratio Scales. Because of the sizes of the objects being represented, different scales are used for drawings (Figure 1-2).

Figure 1-2. Graphic and ration scales

The purpose of construction prints is to be exact (Figure 1-3). Line conventions most often seen on working drawings are:

Visible Lines. A heavyweight unbroken line is used for the primary feature of a drawing. For drawings of objects, this line convention represents the edges, the intersection of two surfaces, or the surface limit that is visible from the viewing angle of the drawing. This lines is often called the outline.

Hidden Lines. A medium weight line of evenly spaced short dashes represents an edge, the intersection of two surfaces, or the surface limit which is not visible from the viewing angle of the drawing.

Center Lines. A thin (light) line composed of alternate long and short dashes of consistent length is called a centerline. It is used to signify the center of a circle or arc and to divide object into equal or symmetrical parts.

Dimension Lines. A solid, continuous line terminating in arrowheads at each end. Dimension lines are broken only to permit writing in dimension. On construction drawings, the dimension lines are unbroken. The points of the arrowheads touch the extension lines which mark the limits of the dimension. The dimension is expressed in feet and inches on architectural drawings and in feet and decimal fractions of a foot on engineering drawings.

Extension lines. An extension line is a thin (light), unbroken line that indicates the extent of the dimension lines. The extension line extends the visible lines of an object when it is not convenient to draw a dimension line directly between the visible lines. There is always a small space between the extension line and the visible line.

Figure 1-3. Line conventions

 Architectural Symbols. These symbols are used on drawings to show the type and location of doors, windows, and material conventions. To understand construction drawings, you must be able to recognize and interpret these symbols (Figure 1-4).


Figure 1-4. Architectural symbols

1-2. Working Drawings.

Working drawings and specifications are the main sources of information for supervisors and technicians responsible for the actual construction. The construction working drawing gives a complete graphic description of the structure to be erected and the construction method to be followed. A set of working drawings includes both general and detail drawings. General drawings consist of plans and elevations; detail drawings consist of sections and detail views.

Site Plan. A site plan (also called a plot plan) (Figure 1-5) shows the boundaries of the construction site, the location of the building in relation to the boundaries, the ground contour, and the roads and walks. It may also show utility lines such as sewer, gas, and water. This type of plan is drawn from a survey of the area by locating the corners of the building at specific distances from the established reference points.

Figure 1-5. Site plan
(Click the image for a larger version)

 Elevations. Elevations are drawings that are commonly used to show exterior views of a structure from the front, rear, left, and right sides (Figure 1-6). They show a picture-like view as it would actually appear on a vertical plane. You must have a good overall idea of the structure before you examine it in detail. Elevations also show the types of doors and windows (drawn to scale) and how they will appear on the finished structure. Ask yourself does the structure have a simple roof? Is the floor level close to ground level (grade)?

Figure 1-6. Elevation views

Elevations are made more lifelike by accenting certain lines and adding straight lines to represent the types of materials used on the exterior (Figure 1-7). Lines that may be accented are window, door, roof, and building outlines. When accenting lines, you must assume that the light is coming from a certain direction and that accented lines represent shaded areas. Using straight lines to suggest the texture of exterior materials is a form of architectural rendering. Rendering, as applied to architectural drawings, is the use of a pencil, ink, watercolors, or a combination of these to depict (paint) a structure and bring out its form or shape.

Figure 1-7. Accent lines

Floor Plan. A floor plan is a cross-sectional view of a building. The horizontal cut crosses all openings, regardless of their height from the floor. The development of a floor plan is shown in Figure 1-8. Note that a floor plan shows the outside shape of the building the arrangement, size, and shape of the rooms; the type of materials; and the length, thickness, and character of the building walls at a particular floor. A floor plan also includes the type, width, and location of the doors and windows; the types and locations of utility installations; and the location of stairways. A typical floor plan is shown in Figure 1-9.

(1) Drawings and Specifications. Drawings and specifications inform the contractor, owner, material dealers, and tradespeople of decisions made by the architect and owner of the structure. Floor plans are usually drawn to scale (1/4" = 1' or 3/16" = 1'). Symbols are used to Indicate different types o fixtures and materials.

Note

Electrical, heating, and plumbing layouts are either on the floor plan or on separate drawings attached to the floor plan.

(2) Floor Plan Details. Detailed drawings may appear on the plan or on separate sheets attached to the plan. When detailed drawings are on separate sheets, a reference symbol is drawn on the floor plan. A door and window schedule is presented on the plan (see sample on Table 1-2 is a sample showing the information given on the schedule.

Figure 1-8. Floor-plan development

 

Table 1-2. Door and window schedule

 

Figure 1-9. Typical floor plan
(Click the image for a larger version)

Detail Drawings (Sections and Details). Detail drawings are drawn to a larger scale than plans and elevations to give more elaborate information, dimensions, and details. For example, they may give the size of materials and show the placement of parts in relation to each other.

(1) Sections. Sections are drawn to a large scale showing details of a particular construction feature that cannot be given in a general drawing. They show:

  • Height.
  • Materials.
  • Fastening and support systems.
  • Any concealed features.

(a) Wall section. A typical section, with parts identified by name and/or size, is illustrated in Figure 1-10. This figure shows how a structure looks when cut vertically by a cutting plane. Wall sections are very important to construction supervisors and to the craftsmen who do the actual building. They show the construction of the wall, as well as the way in which structural members and other features are joined to it. Wall sections extend vertically from the foundation bed to the roof. Sections are classified typical and specific. Figure 1-11 shows a typical window section.

(b) Typical sections. Typical sections are used to show construction features that are repeated many times throughout a structure.

(c) Specific sections. When a particular construction feature occurs only once and is not shown clearly in the general drawing, a cutting plane is passed through that portion.

Figure 1-10. Typical wall section

Figure 1-11. Window section

(2) Details. Details are large-scale drawings which show features that do not appear (or appear on too small a scale) on the plans, elevations, and sections. Sections show the builder how various parts are connected and placed. Details do not have a cutting-plane indication but are simply noted by a code. The construction of doors, windows, and eaves is usually shown in detail drawings. Figure 1-12 shows some typical door-framing details, window wood-framing details, and an eave detail for a simple type of cornice. Other details that are customarily shown are sills, girder and joint connections, and stairways.

Figure 1-13 shows how a stairway is drawn in a plan and how riser-tread information is given. For example, on the plan, DOWN 17 RISERS followed by an arrow means that there are 17 risers in the run of stairs going from the first floor to the floor below, in the direction indicated by the arrow. The riser-tread diagram provides height and width information. The standard for the riser, or height from the bottom of the tread to the bottom of the next tread, ranges from 6 1/2 to 7 1/2 inches. The tread width is usually such that the sum of riser and tread is about 18 inches (a 7-inch riser and 11-inch tread is standard). On the plan, the distance between the riser lines is the width of the tread.

Figure 1-12. Typical eave, door, and window details

 

Figure 1-13. Stairway and steps

Wood-Framing Drawing. Framing plans show the size, number, and location of the structural members constituting the building framework. Separate framing plans may be drawn for the floors, walls, and roof. The floor-framing plan must specify the sizes and spacing of joists, girders, and columns used to support the floor. Detail drawings are added, if necessary, to show the methods of anchoring joists and girders to the columns and foundation walls or footings. Wall-framing plans show the location and method of framing openings and ceiling heights so that studs and post can be cut. Roof-framing plans show the construction of the rafters used to span the building and support the roof. Size, spacing, roof slope, and all necessary details are shown. Working prints for theater of operation (TO) buildings usually show details of all framing.

Light Wood Framing. Light framing is used in barracks, bathhouses, administration buildings, light shops, hospitals, and similar structures. Detailed drawings of foundation walls, footings, posts, and girder details normally used in standard TO construction are shown in Figure 1-14.

Figure 1-14. Typical foundation wall, post, footing, and girder details

The various details for overall framing of a 20-foot-wide building (including ground level, window openings, brace, splices, and nomenclature of framing) are shown in Figure 1-15.

Figure 1-15. Light framing details (20-foot-wide building)
(Click the image for a larger version)

A construction drawing shows the type of footings and size of the various members. Some drawings give the various lengths, while others specify the required lengths on the accompanying BOM. Figure 1-16 shows floor-framing details showing footings, posts, girders, joists, reinforced sections of floor for heavy loads, section views covering makeup of certain sections, scabs for joint girders to posts, and post-bracing details as placed for cross sections and longitudinal sections.

Figure 1-16. Floor-framing details (20-foot-wide building)
(Click the image for a larger version)

Wall framing for end panels is shown in view A in Figure 1-17. Wall-framing plans are detail drawings showing the locations of studs, plates, sills, and bracing. They show one wall at a time. The height for panels is usually shown. From this height, the length of wall studs is determined by deducting the thickness of the top or rafter plate and the bottom plate. Studs placed next to window openings may be placed either on edge or flat, depending on the type of windows used. Details for side panels (view B) cover the same type of information as listed for end panels. The space between studs is given in the wall-framing detail drawing, as well as height of girt from bottom plate and types of door and window openings, if any. For window openings the details specify whether the window is hinged to swing in or out, or whether it is to be a sliding panel.

Figure 1-17. Typical wall-panel framing details

Examples of drawings showing the makeup of various trussed rafters are given in Figure 1-18. A 40-foot trussed rafter showing a partition bearing in the center is shown in view A. The drawing shows the splices required, bracing details, the stud and top plate at one end of the rafter, and the size of the members.

Figure 1-18. Trussed-rafter details

A typical detail drawing of a 20-foot truss rafter is shown in view  Use filler blocks to keep the brace members in a vertical plane, since the rafter and bottom chord are nailed together rather than spliced. The drawing shows placement of the rafter tie on the opposite side from the vertical brace. Usually the splice plate for the bottom chord (if one is needed) is placed on the side where the rafters are to be nailed so that it can also serve as a filler block.

Use a modified truss, shown in view C, only when specified in plans for certain construction. It should not be used in areas subject to high wind velocities or moderate to heavy snowfall. In this type of trussed rafter, the bottom chord is placed on the rafters above the top plate. The construction plans specify the best type of trussed rafter for the purpose. The drawings must show, in detail, the construction features of the rafter selected.

Heavy Wood Framing. Heavy wood framing consists of framing members (timber construction) at least 6 inches in dimension (for example, 2 by 6 inches or 4 by 12 inches). Examples of this type framing are heavy roof trusses, timber-trestle bridges, and wharves. The major differences between light and heavy framing are the size of timber used and the types of fasteners used.

Foundation Plan. Figure 1-19 shows a foundation plan. The foundation is the starting point of the construction. Detail drawings and specifications for a plan are usually attached on a separate sheet.

Figure 1-19. Foundation plan
(Click the image for a larger version)

David L. Heiserman, Editor

Copyright   SweetHaven Publishing Services
All Rights Reserved

Revised: June 06, 2015