Home                                                The Basics of Reading Blueprints

Glossary of Building Terms


The most important aspect of a new home is the purchase of or the drawing of construction plans. Using the least expensive designer or purchasing stock plans that are not adequately drawn could cost thousands of dollars during construction.
The plans list the services and materials needed to build a home. Contracts and agreements are based on your plans and it is of utmost importance they be complete, clear, and comprehensive, to insure that the home is properly constructed, in an honest, orderly and timely manner.
The plans must comply with national and local building codes, and include all drawings, schedules, and specifications necessary for take-offs, bids, permits, and construction.

Plot Plans are drawn to determine the placement of the home on the building lot. A plot plan again is an overhead view of the construction site and the home as it sits in reference to the boundaries of the lot. Stock house plans usually do not include plot plans since they are drawn specific to the site where it will be built. Plot plans can be drawn by a local professional draftsman, architect or engineer. Plot plans should outline location of utility services, setback requirements, easements, location of drives and walks, and sometimes even topographical data that specifies the slope of the terrain.

Perspective View:


Home plans are drawn to scale so that if a specific dimension needed is missing, the contractor can scale the drawing to determine the right measurement. 

Typical scales used in the United States are:

  • Full scale, with inches divided into sixteenths of an inch

The following scales are generally grouped in pairs using the same dual-numbered index line:

  • three-inches-to-the-foot (3"=1'-0") (ratio equivalent 1:4)/one-and-one-half-inch-to-the-foot (1-1/2"=1'-0") (1:8)
  • one-inch-to-the-foot (1"=1'-0") (1:12)/one-half-inch-to-the-foot (1/2"=1'-0") (1:24)
  • three-quarters-inch-to-the-foot (3/4"=1'-0") (1:16)/three-eighths-inch-to-the-foot (3/8"=1'-0") (1:32)
  • one-quarter-inch-to-the-foot (1/4"=1'-0") (1:48)/one-eighth-inch-to-the-foot (1/8"=1'-0") (1:96)
  • three-sixteenths-inch-to-the-foot (3/16"=1'-0") (1:64)/three-thirty-seconds-inch-to-the-foot (3/32"=1'0") (1:128)

The main floor plans are generally drawn to Ό" scale which means that every Ό" on the plan equals 1' in actual length. Other details like framing layouts or built-in details may be drawn at another scale like 1/8" or even Ύ". The scale of each drawing is usually called out beneath the drawing or somewhere on the page, usually next to the title.


Elevations are a non-perspective view of the home, straight on. These are drawn to scale so that measurements can be taken for any aspect necessary. Plans include front, rear and both side elevations. The elevations specify ridge heights, the positioning of the final grade of the lot, exterior finishes, roof pitches and other details like windows, doors, gables, hips, that are necessary to give the home its exterior architectural styling.

Basement Floor Plan: The basement or foundation plan delineates the location of bearing walls that will support the structure. It also identifies locations of footings, steel (rebar) placement, hurricane strap placement and other structural elements that are required to support the loads of the upper floors.


Floor plans are actually quite easy to understand. A floor plan layout on blueprints is basically an overhead view of the completed house. You'll see parallel lines that scale at whatever width the walls are required to be. Dimensions are usually drawn between the walls to specify room sizes and wall lengths. You'll also see on the floor plan locations of fixtures like sinks, water heaters, furnaces, etc. Among the walls and dimensions you will often find notes to specify finishes, construction methods, or even symbols for electrical or to reference cross sections.

Roof Plan:

Electrical Layout: Electrical layouts are sometimes on a separate page to make reading them a little easier. The layout will show locations of light fixtures, fans, outlets, light switches etc. There is usually a legend on the page which explains what each symbols represents. For illustration purposes we have included such a legend below. There may be such legends for heating systems, door swings and sizes, or even to specify certain finishes.

Framing Drawings: The framing drawings are also drawn to scale and outline the layouts of items such as floor joists and trusses, beam locations and other structural requirements. Framing layouts don't usually get into the details of each stud location in the walls since framing contractors are required to follow certain rules and regulations to assure that the home meets the required building code specifications. Though there are often cross section within the plan pages that outline the general methods of wall construction or floor assembly.

Plumbing and mechanical systems:
These systems are generally not covered extensively on the blueprints other than locations of fixtures and main service lines. If you are going to the expense of more complicated heating systems like in floor radiant heat or even an engineered forced air system, these drawings need to be completed by a heating or plumbing specialist.

Sections and Details: Overhead views or floor plan views of the structure don't always provide enough information on how the home is to be built. Often times cross section or details will explain certain special conditions more appropriately. A cross section is basically a view of the home if it were sliced down the center. This allows you to view the home from the side and understand a little better the relativity of varying floor heights, rafter lengths, and other structural elements.

For a large blown up view of Details Click here

Construction plan specifications in North America:

Specifications form a part of the contract that documents and govern the construction of a building. While there is a tendency to believe that "Specs overrule Drawings" in the event of discrepancies between the text document and the drawings. The actual intent is for drawings and specifications to be complimentary with neither taking precedence over the other.

Sample Specification Legend, not complete
Indicates baseline specifications, lowest cost impact and represents minimum code requirements
Indicates option for sustainable practices may have cost impact
In addition to environmental stewardship, this option indicates a higher level of finish cost and stewardship
Roof structure 2 Options
Engineered scissor trusses at 24” O.C. Fill void with insulation (see insulation options)
Custom exposed wood trusses with “SIPS” roof system
See structural drawings for roof structure upgrade
Roof material
30-year composition roofing over 30 lb. building paper
Light colored 40-year composition roofing over 30-lb building paper
Provided “ algae block” recycled content
  • Architectural shingles” 40 year composition roofing over 30-lb building paper
  • Terne coated stainless steel standing seam metal roof
Stamped engineered truss details are required to be submitted and reviewed prior to the construction of the roof.
Fiberglass Batt insulation at walls and at floor
2” spray-in polyurethane with BATTS in vault cavities, formaldehyde free
Blown in walls, cellulose, polyurethane
Windows and Doors
Vinyl windows with low “E” coating “U” value = .40 (code minimum)
  • Fiber glass frame windows with low “E” coating, “U” value = .35 or less
  • Windows with solar heat gain coefficient (SHGC) =. 40 or less
  • Provide insulated core exterior doors
All wood or aluminum clad wood windows with low “ E” coating, “U” value =. 35
Exterior Cladding Material
Cementitious or wood siding and trim, 6'' T&G with 3'' lap profile, no texture over 20 lb. building paper. Trim material to be 2x6 nominal
Cementitious siding, 6’’ T&G with 3’’ lap profile, no texture over siding infiltration barrier building wrap, recycled content, see details flashing
Cementitious siding, 6’’ T&G with 3’’ lap profile, no texture over 20 lb. building paper, trim material to be 2x6 nominal
Lumber and Wood Products:
Standard lumber and wood composites
FSC certified lumber for framing members and sheathing
Type and tonnage of unit:
4 ton Lennox


family room Wood finish, bedrooms, carpet
Concrete, see structural
Concrete w/ 25% fly ash, non-toxic form, release reusable forms
Concrete w/ 10% fly ash

Specifications can be "performance-based", whereby the specifier restricts the text to stating the performance that must be achieved in each Section of work, or "prescriptive", whereby the specifier indicates specific products, vendors and even contractors that are acceptable for each workscope. Specifications of some sort are a must for a contractor to properly bid the cost of a job. All building material must be identified as to grade and placement, such as steel in concrete, concrete PSI slab, grade of lumber, plywood, plumbing, shingles, sheetrock, paint, floors, and especially wall and ceiling insulation, or entire envelope insulation.

These are the basics of reading a house plan; keep in mind however that what is included in plans will vary according to the designer who drew them. House plans are a very important part of the homebuilding process. It is crucial to purchase a plan drawn by a home design professional since they have a thorough understanding of how homes are built. If there were any terms on this page that you did not understand or would like a more thorough description of their meaning, please visit our construction terms glossary.

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