Providing accurate construction drawings up front helps ensure that construction projects will proceed in an orderly manner, reducing costly and time-consuming rework by contractors and subcontractors down the line. Construction drawings are generally categorized according to their intended purpose. Types commonly used in construction may be divided into five main categories based on the function they intend to serve:
1. Preliminary drawings
2. Presentation drawings
3. Working drawings
4. Shop/assembly drawings
5. Specialized and miscellaneous drawings
At the initial promotional stages of a project, the architect or designer often prepares preliminary sketches, which are essentially schematic design/concept-development drawings. These provide a convenient and practical basis for communication between the designer and the owner in the idea formulation stage. During the design phase, these drawings go through many alterations, helping the client to determine the most aesthetically attractive and functional design. These drawings are not meant for construction but rather for exploratory purposes, providing an overall concept that reflects the client's needs, as well as functional studies, materials to be used, preliminary cost estimates and budget, preliminary construction approvals, etc. Preliminary drawings are also typically used to explore with other consultants concepts relating to the mechanical, plumbing, and electrical systems to be provided. These are followed by formal design-development drawings prior to the working-drawing or construction-document stage.
The purpose of presentation drawings is to present the proposed building or facility in an attractive setting at the proposed site for promotional purposes. They usually consist of perspective views complete with colors and shading, although they may also contain nicely drawn elevation views with shadows and landscaping (Figures 2.7A and B). Presentation drawings are therefore essentially selling tools, a means to sell the building or project before it reaches the working-drawing stage, and are used in brochures and other outlets. This phase is also where the schematic design is developed, finalized, and approved by the client.
Also called project and constructions drawings, working drawings include all the drawings required by the various trades to complete a project. These drawings are technical and are intended to furnish all the necessary information required by a contractor to erect a structure. Working drawings show the size, quantity, location, and relationship of the building components. They are typically prepared in considerable detail by the architect or engineer, and the amount of time and effort expended on them comprises a major portion of the consultant's design services.
Sometimes the printing may be difficult to read or important information may be missing from the drawings. Occasionally entire pages may be missing, or the contractor may have received only a set of plans or specifications. If the prints are incomplete or of poor quality, the consultant should be immediately notified and asked to address the problem.
Working drawings serve many functions:
1. They are the means for receiving a building permit. Before construction begins, the local building authority has to review the working drawings to ensure that they meet required building codes. A building permit will be issued after approval of the drawings.
2. They are used for competitive bidding. They allow contractors to study the documents and make bids based on their review of the drawings and other documents, thus providing the owner with the most economical cost for construction.
3. They provide instructions for construction. Working drawings should contain all the necessary information to build the structure.
4. They are used for material take-offs. Labor, material, and other estimates are made from working drawings prior to commencement of construction.
5. They provide a permanent record for future use (such as remodeling and dispute resolution).
6. They can be used as a basis for leasing purposes.
7. After the project is awarded, the drawings form the basis of the contract between the contractor, subcontractor, and client.
The pages in a set of blueprints are usually carefully lettered and numbered. The letters shown here are the ones most commonly used in the industry:
• A: Architectural pages
Thus if a set of blueprints consist of 30 pages, it may be numbered as follows: A1 through A8 (eight architectural pages); S1 through S10 (10 structural pages); P1 through P3 (three plumbing pages);M1 through M4 (four mechanical pages); E1 through E5 (five electrical pages).
Shop and assembly drawings are technical drawings prepared by various contractors, subcontractors, and suppliers participating in the construction process to show how their product is to be made. Since many products contain more than one component, shop and assembly drawings (also called fabrication drawings) identify each component and show how they all fit together. These drawings should contain all the necessary information on the size, shape, material, and provisions for connections and attachments for each member, including details, schedules, diagrams, and other related data to illustrate a material, product, or system for some portion of the work prepared by the construction contractor, subcontractor, manufacturer, distributor, or supplier. Product data includes items such as brochures, illustrations, performance charts, and other information by which the work can be evaluated. The infor mation provided must be in sufficient detail to permit ordering the material for the product concerned and its fabrication in the shop or yard. In practice the consultant often has to rely on these specialists to furnish precise information about their components.
In most projects, whether large or small, contractors and subcontractors are frequently required to draft shop drawings even for minor shop and field projects such as doors, cabinets, and the like. Thus, for example, if complex cabinetwork is required, it must be built to exact size and specifications. A shop drawing becomes necessary to ensure that the cabinetwork will fit into the structure and that the structure will accommodate it. In Figure 2.8A we see shop-drawing details for a restaurant waiter station and Figure 2.8B shows how a cabinet is to be assembled. Approval of the shop drawings usually precedes the actual fabrication of the component. Shop drawings also help the consultant check the quality of other components that subcontractors propose to furnish.
Detail drawings provide information about specific parts of the construction and are on a larger scale than general drawings. They show features that do not appear at all or are on too small a scale in general drawings. The wall section and elevator details in Figures 2.9A and B are typical examples and are drawn to a considerably larger scale than the plans and elevations.
Framing details at doors, windows, and cornices, which are the most common types of details, are nearly always shown in sections. Details are included whenever the information given in the plans, elevations, and wall sections is not sufficiently "detailed" to guide the craftsmen on the job. Figure 2.10 shows some typical door and eave details.
A detail contains both graphic and written information. An area of construction is drawn at a larger scale in order to clearly show the materials, dimensions, method of building, desired joint or attachment, and so on.
Details are often drawn as sections. It is as if a slice is made through a specific area and the inner components are visible. In Figures 2.11A and B we see an example of a typical bay window detail.
There are many types of details, all of which are drawn as needed to clarify specific aspects of a design. A drawing sheet will often show several details. The complexity of the project will determine which areas need to be shown at a larger scale.
Details are always drawn to scale. A typical scale for a detail is 3 inches to 1 foot (scale: 3 inches = 1 foot, 0 inches). The scale for each detail will vary depending on how much information is required to make the construction clear to the builder. Each detail will have the scale noted below.
Specialized and Miscellaneous Drawing Types
There are numerous other types of drawings used by architects and engineers in the construction industry.
Freehand sketches are drawings made without the aid of any type of drawing instruments. Sketches can be an extremely valuable tool for architects, designers, builders, and contractors. It is often the quickest and most economical method to communicate ideas (Figures 2.12A, B, and C), construction methods, and concepts or to record field instructions. It is an ideal method to sell an idea to a client and get preliminary approval for a design. Likewise, when installing mechanical or electrical systems and circuits, you may sometimes have to exchange information about your job with others. A freehand sketch can be an accurate and appropriate method to communicate this information. This type of drawing is informal in character, may or may not be drawn to scale, and need not follow any particular format. A
sketch can be used in many ways. Another example of where to use a sketch is to show a field change that must be made. No matter how well a project is planned, field changes may sometimes need to be made, and a sketch will often go a long way to helping the builder visualize the designer's intention or the construction techniques to be used. Sketches may include dimensions, symbols, and other information needed to convey your idea of the required change to someone else (such as the project supervisor or project chief).
Erection drawings, or erection diagrams, indicate the location and position of the various members in the finished structure. Erection drawings are especially useful to builders performing the erection in the field. The information erection drawings show includes supplying the approximate weight of heavy pieces, the number of pieces, and other helpful data.
Framing drawings are necessary to show the layouts and provide other relevant information about the various framing components. These include floor joists, trusses, beam locations, and other structural elements. Framing layouts are drawn to scale but don't normally get into the details of each stud location in the walls, because framing contractors are required to follow certain rules and regulations to assure that the structure meets the required building-code specifications.
Falsework drawings show temporary supports of timber or steel that are required sometimes in the erection of difficult or important structures. When falsework is required on an elaborate scale, drawings similar to the general and detail drawings already described may be provided to guide construction. For simple falsework field sketches may be all that is needed.
Master-plan drawings are commonly used in the architectural, topographical, and construction fields. They show sufficient features to be used as guides in long-range area development and usually contain a considerable amount of information including section boundary lines, contour lines, acreage, existing utilities, rights-of-way and appurtenances, horizontal and vertical control data, locations and descriptions of existing and proposed structures, existing and proposed surfaced and unsurfaced roads and sidewalks, streams, and north-point indicator (arrow).
Was this article helpful?
How would you like to save a ton of money and increase the value of your home by as much as thirty percent! If your homes landscape is designed properly it will be a source of enjoyment for your entire family, it will enhance your community and add to the resale value of your property. Landscape design involves much more than placing trees, shrubs and other plants on the property. It is an art which deals with conscious arrangement or organization of outdoor space for human satisfaction and enjoyment.