Blueprint Reading

94 flashcards by MentisLibrary

Reading a construction drawing set: sheet numbering and title blocks, scales and dimension strings, line types, sections and details, schedules and wall tags, structural callouts, and the civil, plumbing, mechanical and electrical sheets.

What is a construction drawing set, and what is its relationship to the specifications?
The drawings show quantity, location and geometry. The specifications describe quality, materials, standards and workmanship. Together with the agreement and the general conditions they form the contract documents, and neither one alone is complete.
In what order is a drawing set normally assembled?
Cover sheet and index first, then general, civil, landscape, structural, architectural, interiors, fire protection, plumbing, mechanical, electrical and telecommunications, roughly in the order the building is built.
What do the discipline letters on a sheet number mean?
Under the National CAD Standard, G is general, C civil, L landscape, S structural, A architectural, I interiors, F fire protection, P plumbing, M mechanical, E electrical and T telecommunications, among others.
What does the first digit after the discipline letter tell you?
The sheet type: 0 for general information such as legends and notes, 1 for plans, 2 for elevations, 3 for sections, 4 for large scale views, 5 for details, 6 for schedules and diagrams, and 9 for three dimensional representations.
What information does the title block carry?
Project name and address, the design firm, sheet title and number, the drawing scale or a note that scales vary, the issue date, the revision block, and the seal of the licensed professional responsible.
What is a revision cloud, and what is the delta beside it?
The cloud outlines the area of the sheet that changed. The numbered triangle, called a delta, identifies which revision made the change and ties back to the revision block in the title block.
What is a sheet index, and why is it worth reading first?
The list of every sheet in the set, on the cover or a general sheet. Comparing it to the sheets you were given is the fastest way to find out what is missing.
What is a general note versus a keyed note?
General notes apply to everything on the sheet or the whole set. Keyed notes are numbered and apply only where their symbol appears on the drawing.
What is a legend on a drawing?
The key that defines the symbols, line types, hatch patterns and abbreviations used in that discipline's sheets.
What is CSI MasterFormat, and how is the project manual organized?
A standard numbering system for specification sections. The current format uses 50 divisions. Division 01 covers general requirements, then 03 concrete, 04 masonry, 05 metals, 06 wood and composites, 07 thermal and moisture protection, 08 openings, 09 finishes, then the facility services divisions in the twenties and site work in the thirties.
How is an individual specification section organized?
In three parts: Part 1 General, covering submittals, references and quality requirements; Part 2 Products, covering materials and manufacturers; Part 3 Execution, covering installation, tolerances and testing.
What is the standard architectural scale for a residential or small commercial floor plan?
1/4 in equals 1 ft 0 in, which is a ratio of 1 to 48. Larger buildings are usually drawn at 1/8 in equals 1 ft 0 in, a ratio of 1 to 96.
How do you convert an architectural scale to a ratio?
Divide 12 in by the scale value in inches per foot. At 1 in equals 1 ft the ratio is 1 to 12, at 1/2 in it is 1 to 24, at 1/4 in it is 1 to 48, at 1/8 in it is 1 to 96.
What is the difference between an architect's scale and an engineer's scale?
An architect's scale is divided in feet and inches with fractional inch increments and is used for buildings. An engineer's scale is divided decimally in units of 10, 20, 30, 40, 50 and 60 parts per inch and is used for site and civil work.
Why does nearly every drawing set say do not scale drawings?
Because written dimensions govern. Printing, reproduction, paper stretch and half size copies all change the measured length on paper, but a written dimension cannot change.
What happens to the scale when a drawing is printed half size?
Every scale is halved. A drawing at 1/4 in equals 1 ft 0 in becomes 1/8 in equals 1 ft 0 in on the half size print, so a standard scale rule no longer reads correctly against it.
What are the common architectural sheet sizes?
ARCH D at 24 by 36 in and ARCH E at 36 by 48 in are common for full size sets. ANSI D at 22 by 34 in and ANSI E at 34 by 44 in are also used, and 11 by 17 in is the usual half size format.
What is the order of precedence when documents conflict?
The contract's general conditions state it for that project, but the common ordering is that later documents such as addenda and change orders govern over earlier ones, and larger scale details govern over smaller scale plans. Written dimensions always govern over scaled measurements.
What do you do when the drawings and specifications conflict?
Submit a request for information rather than choosing one. An RFI creates a written answer that becomes part of the record, and it protects you when the cost or schedule impact is decided later.
What are the main line types on a construction drawing?
A solid heavy line is a visible object line. A dashed line is a hidden object or, on a demolition plan, something being removed. A long-short-long line is a center line. Thin lines with arrows are dimension lines. A heavy line with arrows at both ends is a section cut. Long dashes with two dots are commonly a property line, and a jagged or wavy line is a break line.
What is a match line, and when is it used?
A heavy line marking where one sheet's coverage ends and another begins, used when a building is too large to fit on one sheet at a usable scale. It carries a note naming the continuing sheet.
What is a key plan?
A small simplified plan of the whole floor, with the portion covered by the current sheet shaded, so you can orient a partial plan within the building.
What is the difference between a plan, an elevation and a section?
A plan is a horizontal cut viewed from above. An elevation is a straight-on view of a vertical face with no cut. A section is a vertical cut through the building or an assembly, viewed straight on.
What is a reflected ceiling plan?
A plan of the ceiling drawn as if a mirror were laid on the floor and you were looking down at the reflection. Because of that convention the ceiling plan has the same left to right orientation as the floor plan.
How do you read a section cut symbol?
The heavy cut line marks where the cut is taken and the arrowheads point in the direction of view. The number in the bubble identifies the section, and the number below the line identifies the sheet where that section is drawn.
How is a detail callout read?
A circle or bubble with the detail number above a line and the sheet number below it, attached by a leader to the area being detailed.
What is an enlarged plan?
A portion of a floor plan redrawn at a larger scale so that small, dimensionally critical areas can be fully dimensioned and annotated.
What is a column grid, and how is it labeled?
A network of reference lines through the building's structural columns. One direction is labeled with numbers and the perpendicular direction with letters, and grid bubbles carry the labels at the ends of the lines.
Where are grid dimensions usually taken from?
From the grid line itself, which is normally the centerline of the column or the structural member, not from a face.
What is a north arrow, and what is project north?
The north arrow shows orientation. Project north, sometimes called plan north, is a simplified orientation used so the building sits square on the sheet, and it may differ from true north.