How to Read Architect's Drawings

The first requirement in constructing a building project is to understand architectural drawings (blueprints, or in this article, referred to as plans). Here is a basic overview of reading these plans.

Steps

1. • Cover sheet. This will contain the project name, the architect's name, address, and contact information, the project location, and the date. This page is very similar to the cover of a book.
   • Plan Index. This page (pages) will have an index of plan sheets (and sometimes their contents). It also will include an abbreviation key, a scale bar with the plan scale indicated, and occasionally design notes.
   • Location plan. This will have an area map, with an enlarged location map, usually giving enough information to locate the project site from nearby towns or highways. This sheet is not found in all sets of plans.
   • Site plans. These pages usually are numbered starting with a "C", such as Sheet "C 001", "C 002". This will often contain several sheets, showing:
     
     • Topographical Information. This will indicate to the builder the topography (slopes or flatness) of the site.
     • Demolition plan. This sheet (or sheets) will show the structures or features which will be demolished on the site prior to grading for construction. It will have trees or other items which are to remain noted in the keynotes.
     • Site utility plans. This sheet (sheets) will indicate the location of existing underground utilities, so that they can be protected during excavation and construction.
   • Architectural sheets. These sheets will usually be numbered "A", such as "A 001". These sheets will describe and give measurements for the basic footprint of the building. These plan sheets should include the following.
     
     • Floor plans. These sheets will show the location of the walls of the building, and identify components like doors, windows, bathrooms, and other elements. There will be dimensions noted as distances between, or from center to center of walls, width of openings for windows and doors, and changes in floor elevations, if the floor is multilevel. Floor plans consist of various levels of detail depending on the stage of the project. At stage D (planning) drawings may show only the major features of the space. At a tender stage, drawings will be more detailed, illustrating all features of the space at a larger scale to allow a contractor to price the job.
     • Ceiling plans. Here, the architect will show the types, heights, and other feature of ceilings in different locations in the building.
     • Roof framing plan. These pages will indicate the layout for joists, rafters, trusses, bar joists, or other roof framing members, as well as decking and roofing details.
     • Finish schedule. This is usually a table listing the different finishes in each individual room. It should list paint colors for each wall, flooring type and color, ceiling height, type, and color, wall base, and other notes and details for constructing the finish in areas listed.
     • Door/Window schedule. This table will have a list of doors, describing the opening, "hand" of doors, window information (often keyed off of the floor plan, example, window or door type "A", "B", etc.). It will also include installation details (cuts) for flashings, attachment methods, and hardware specifications. There may also be a separate schedule for window and door finishes. A window example would be "Mill finish, aluminum", a door might be "Oak, natural finish".
     • Details. This may include bathroom fixture layouts, casework (cabinets), closet accessories, and other elements not specifically noted on other sheets.
     • Elevations. These are views from the exterior, indicating the material used in exterior walls, (brick, stucco, vinyl, etc), the location of windows and doors from a side view, the roof slopes, and other elements visible from the exterior.
   • Structural plans. The structural plans usually are numbered beginning with "S", as in "S 001" These plans include reinforcement, foundations, slab thicknesses, framing materials, (lumber, concrete pilasters, structural steel, concrete block, etc.)
     
     • Foundation plan. This sheet will show the size, thickness, and elevation of footings (footers), with notes regarding the placement of reinforcing bars (rebar). It will note locations for anchor bolts or weld plate imbeds for structural steel, and other elements. A footing schedule is often shown on the first sheet of structural notes, as well as notes regarding the reinforcing requirements, concrete break strength requirements, and other written statements for structural strengths, and testing requirements.
     • Framing plan. This will indicate the material used for framing the building. This may include wood or metal studs, concrete masonry units, or structural steel.
     • Intermediate structural framing plans. These are used for multistory construction, where each level may require support columns, beams, joists, decking, and other elements.
   • Plumbing plan. Plumbing drawing pages are numbered beginning with "P". These sheets will show the location and type of plumbing incorporated in the building.
     
     • Plumbing rough-in. This sheet will show the location of pipes which are to be "stubbed up" to connect the plumbing fixtures to water supply, drain/waste, and vent systems.
     • Plumbing floor plan. This sheet will show the location and type of plumbing fixtures, as well as the route pipes will be run (overhead or through walls) for potable water and drain, waste, and vents.
   • Mechanical drawings. Mechanical pages are numbered beginning with "M". This sheet (or sheets) will show the location of HVAC (heating, ventilation, and air conditioning) equipment, duct work, and refrigerant piping, as well as control wiring.
   • Electrical plan. The electrical drawings are numbered beginning with "E". This sheet (sheets) shows the location of the electrical circuits, panel boxes, and fixtures throughout the building, as well as switchgears, subpanels, and transformers, if incorporated in the building. Special pages found in the electrical plan pages may be "riser" details, showing the configuration of power supply wiring, panel schedules, identifying specific breaker amperages and circuits, and notes regarding types and gauges of wires and conduit sizes.
   • BMP (Best Management Practices) drawings, or environmental plans. This sheet will indicate protected areas of the site, erosion control plans, and methods for preventing environmental damage during construction. There may be details in the BMP drawings showing tree protection techniques, silt fence installation requirements, and temporary storm water retainage measures. The requirement for a BMP plan originates under the environmental protection department of your local, state, or national governing authority.
2. Locate the element of construction you are reviewing to implement a portion of your work. If you are laying out the location of the building, you will first look at the site plan for location of existing buildings, structures, or property lines so you have a reference point to begin measuring to your building footprint. Some plans simply give a coordinate grid position using northings and eastings, and you will need a "total station" surveyor's transit to locate these points. Here are some example steps for laying out a building foot print from architectural plans.
   
   • Lay out your building on the site by either the above referenced plan or the measurements given on the site plan. Measure to locations, preferably corners, on one side of the building, and check for any "checkpoints" to verify the accuracy of your layout. If you cannot absolutely establish an exact building line, you may have to suppose the location is correct and continue. This is widely accepted in cases where the site is very large, allowing for tolerance, but on a crowded lot or site, the location must be exact.
   • Establish the elevation you will work from. This may be a height relative to a nearby roadway, or an elevation determined from sea level. Your site plan or architectural floor plan should have a bench mark(a bench mark refers to some item, such as a manhole lid or survey waypoint with a known elevation) elevation or a "height above existing grade" as a starting point.
   • Use your plan to measure the location of each corner of the building, including offsets. Remember what exact element of construction you are using for your layout. You may mark an outside wall line, a foundation line, or a column line, depending on the type of construction and the most practical element for making subsequent measurements. For instance, if you are building a structural steel building with I-beam columns which require setting anchor bolts to secure them, you may begin your building layout with the centerline of these columns, where if you are building a wood-framed residential structure with a monolithic slab floor, the edge of the slab would be your best choice for the initial layout.
3. Reference the description of various sheets to find an element of construction you are going to use in the work you will perform. Plumbers use the Architect's floor plan to locate walls so the pipes they stub up will be concealed inside the wall cavity when the building is constructed, then use their plumbing floor plan to find out what types and sizes of pipes are required to service a particular fixture.
4. Use the dimension scale where measurements are not provided. As a rule, architectural plans are drawn to a "scale". An example would be, 1 inch equals 10 feet (1"=10'), so measuring between to walls on the plan sheet means for each inch, the distance is 10 feet. A scale rule[[1]] will make this much easier, but be careful to match the rule scale to the plan's scale. Architects often use a scale of fractions, such as a 1/32 scale, engineers usually use an inch per foot scale. Some plans or details are not to scale, and should be marked "(NTS)".
5. Read all notes on a page. Often a particular element has special considerations which are more easily described verbally than drawn, and notes are a tool the architect will use to illustrate them. You may see a table of notes on the side of a sheet, with numbers identifying the note location on the plan (a number with a circle, square, or triangle around it) and a corresponding numbered statement describing the situation on the side of the sheet.
6. Learn to recognise the different types of lines the architects and engineers may use. You should have a specific keynote table for section of plans, and this will provide information on the abbreviations, symbols, and specific lines used in each section of the plans. An example would be in the electrical plans, a circuit may have the "home run" "leg" (the wire going from the first junction box in a circuit to the panel box (the power source) highlighted or in darker ink than other circuits, and exposed conduits may be indicated by a solid line, and concealed conduits by a dotted or broken line. Because there are many different line usages indicating different type walls, piping, wiring, and other features, you will have to see individual plan page "key notes" to understand them.
7. Use a "Builder's" calculator to add dimensions when determining distances on your plans. These are calculators which add feet and inches, fractions, or metric measurements. Often, an architect will not give a measurement to a specific plan item, from a baseline such as the "'OBL" (outside building line), so you will need to be able to add the distances each feature which has a measurement provided, to get the total distance. An example would be finding the center line of a bathroom wall to locate the potable water pipe stub up. You may have to add the distance given from the OBL to the living room wall, then the distance to a hallway wall, then across a bedroom, to the bathroom wall in question. This might look like (11' 5) + (5' 2") + (12' 4")= 28' 11".
8. Use CAD (Computer Assisted Design) building plans. If you have a set of architectural plans in an electronic form, as on a CD, you will need a version of the original "cad" program which created it to open the files. "AutoCAD" is a popular, but very expensive, professional design program, and the designer will usually include a "Viewer" on the disc which you can install on your computer to view files, so that actual plan pages appear on your screen, but without the full program, you cannot manipulate design components or change the drawings.
9. Learn how to handle architect's plans. These sets of documents are often very large sheets, about 24" X 36", and full construction sets may include dozens, or hundreds of pages. They are either bound or stapled on the left edge, and allowing them to be torn from the bindings, ripped apart by mishandling, laid out in the sun to fade the ink, or left in the rain can make them difficult to use. These documents can cost hundreds of dollars (US) to replace, so try to protect them, and have a flat, wide, protected work surface to unroll and read them on.
10. Remember that the building plans for a project often include contract documents other than the Architect's Drawings.
11. Specifications are usually printed and kept in a binder, and they list descriptions of methods and materials used in the project, as well as testing methods, quality control information, geotechnical data, and other information useful in building the project.
12. Look for notes and symbol referring to "alternate bid items" and "addenda". These may indicate portions of work which are incorporated in the Architect's drawings, but not in the builder's contract to construct, supply, or install. "NIC" is an abbreviation for Not In Contract, which means a certain item will be put in a certain place by the owner after the project is finished. "OFCI" or "GFCI" (Owner Furnished, Contractor Installed, or Government Furnished, Contractor Installed) indicate the item is supplied by the customer, but installed by the contractor. Read and understand all abbreviations used in your plans.

Tips

• Be careful your set of drawings are "original size", since many sets of plans are provided in "full" and "half" size sets, you will are able to scale distances with full size drawings without needing to calculate the scale via drafting rulers.
• If the drawings are true half size, you will need to divide your readings from your ruler by 2. Note: most half size drawings do not state they are half size or other. Basically to consider anything a half size drawing, it will normally be less then a 24x18 (Arch C) sized sheet. Keep in mind, sometimes a half size sheet is called a half size even when its plotted from a 30x44 to a 11x17 size set, rendering it no longer a true half size.
• When doing actual construction from architect's plans, keep one set onsite to record changes with a red ink pen or pencil. These are called "redline drawings". When a job has been fully constructed, redlines are usually provided back to the drafter. These drawings are called "Record Drawings" (RD's) or "As-Builts". These are the site survey redlines which are different from the original set of drawings (aka corrections).
• Use a "triangle" type architect's or engineer's rule for scaling distances on plans. These are shaped so that they offer a flush contact with the plan page so exact positioning of the rule is possible, decreasing the possibility of error.
• Look at house plan books or online to get an idea of the lines, measurements, and basic appearance of plans.

Warnings

• When in doubt of a measurement or other description contained in the plans, consult the architect who drew them, rather than taking a chance on an error that can be difficult to correct at a later date.
• Be aware that plumbing, electrical, and mechanical plans do not always allow for each trade to have sufficient room in individual locations, so care should be taken to coordinate installation of the components of each trade to avoid conflict.
• Be sure to obtain all necessary building permits before any construction work is started. Building inspectors can stop work on any project that requires a permit and does not have one posted. Fines are also issued.

Things You'll Need

• A "Plan Table"
• Architect's triangle scale
• Engineer's triangle scale
• Highlighters are useful in marking plan notes for reference
• Builder's calculator

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