Commercial Steel Estimating. Kerri OlsenЧитать онлайн книгу.
that the designers are asked to clarify ambiguous conditions, and the answers to those questions, are clarified in an Addendum to the bid documents. Addendums are intended to help everyone understand how to assimilate the information correctly.
This chapter should help steel estimators understand how the project specifications affect the creation of a steel estimate. It reviewed the specific sections of Division 5—Structural and Miscellaneous Steel, showing what the different elements within the specifications mean for steel fabricators and how these items affect pricing. Particular attention has been given to key items within the bid documents that may need to be added at the inclusions, exclusions, or qualifications in the bid letter.
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Contract drawings are the group of drawings that are created by the architect, structural engineer, civil engineer, mechanical engineer, and electrical engineer.
These drawings are categorized by Civil, Landscape, Architectural, Structural, Mechanical and Electrical sheets. The Civil drawing number system will begin with a C, landscape drawings with an L, architectural drawings with an A, structural drawings with an S, mechanical drawings with an M, and electrical drawings with an E. Most numbering systems for contract drawings work this way, but there are the exceptions. Therefore, you will need to temper this information with what you are given for your prospective project.
Steel for the project is mostly shown in the A and S drawings. On occasion there may be steel items that are shown only on the Civil, Landscape (e.g., pipe bollards, site handrail, trash enclosures), and Mechanical drawings (support brackets for mechanical). These would need to be provided by the steel fabricator. Therefore, all drawings will need to be checked for steel items in the initial review prior to take off.
The numbering system that is used most often for each group begins with the letter to designate the type of work. After the letter, the drawings are placed numerically, although there appears to be no standardized system. Most designers use a numbering system that will let them insert drawings later, providing for more details. The need for this flexibility is individual to the job. Therefore, numbering systems vary, although generally the lettering indicators remain the same.
Figure 5.1 Plan view of a building’s foundation
Although there are industry standards regarding the creation of drawings, different design teams have their own style of presentation. As with any spoken language, inflections and accents come out in speech; the same happens in bid document drawings. When you begin to recognize these design professionals’ traits, the drawings become easier for you to read and understand.
Reading contract drawings is a skill you learn by doing. Designers have individual styles for presenting the information in their drawings. It’s your job to understand their language. If you don’t understand what they are trying to show, find out. Call the architect or engineer who prepared the drawings; ask them to help you. Another option is to contact one of the trusted general contractors for assistance. Ultimately, the best help for interpreting drawings will come from the designers who created them; after all, they should know what they were trying to accomplish.
Sometimes the detail cuts are in the wrong place or have not been made where they are needed. Catching such errors or omissions can be important not only for the steel estimators, but also for other contractors who use the drawings.
A Plan View drawing is a map or a floor plan where you are looking down on the building. It is standard that the drawing is laid out so that the nominal north of the building is at the top of the sheet, south at the bottom, and thus west at the left and east at your right. (Note: The drawing will also indicate “true” north, which may not be the same as the directional north on the sheet.) This method, which makes the drawings easier to read, ensures that everyone is on the same page.
To explain how to read these drawings, we will look at a typical floor plan view and an elevation section, then review the subsequent details given to help us see the designer’s intent.
Although every project is different, the general application of the plans, section views, and detail views remain the same. This is true for the architectural drawings and structural drawings alike. Look for clues like grid line locations, which will remain consistent from the plan view to the elevation views, to verify how you view the picture. Elevation cuts and detail section arrows point the way that you need to look when reviewing the sections and details.
Keep in mind the size of the elements you are viewing. Buildings can be hundreds of feet long; the grid lines section the buildings into 20-, 30-, and sometimes even 40- or 50-foot increments. Each section and detail gives you closer views of the building, much like a microscope gives you a closer look.
Figure 5.2 Building elevation views
Figure 5.3 Exterior wall section
First, we will examine a sample plan view from an architectural sheet of a building’s foundation (see Figure 5.1). The plan view has a section view indicator (A/A3.3) at the south end of this building, continuing all the way through the building until it ends at the north or top of this picture. This indicator tells us there is an elevation view through the building—a sideways view, usually beginning at the nearest grid line location.
The grid lines identify the quadrants of the building, indicated by a line through specific locations, usually dimensioned; a number or letter identifies each particular grid. These will be located at the top and to the left or right of the page in the plan views. In Figure 5.1, we see grids 16 through 22 at the top and grids A through F on the right of the drawing.
A plan view looks down on a building from above; a horizontal cut has been made through the building, removing the roof or floor above. The effect is like looking down on a box with the top cut off. The inside elevation view cuts through a building vertically from ceiling to floor—like looking at the inside walls and what is on those walls. (Another example is when a child opens a dollhouse and you can see the height of the upright walls, the windows, doors, stairs, etc.)
To see the inside elevation view, place a box on a flat surface so that you are looking directly into the box from the top—its plan view. For purposes of this example, mark the bottom or plan surface with a P, and mark the left or west side surface of the box as A/A3.3. Now, cut through the corners of the box so that its sides lie down flat on the table. It will form a cross, with the part P in the middle and the one marked A/A3.3 on your left. This is the elevation that the cut intends for you to see.
Thus, Elevation Section A/A3.3 looks to the left of the plan view. The grid lines are shown on the elevation so that grid line E is to the left and grid line A is to the right in