Understanding Blueprints

How to read blueprints

Scale:

Blueprint floor plans are typically drawn to a ¼” scale of the actual size of the home. This way the builder will be able to scale the drawing of the home and come up with the correct measurement. As a generally accepted rule a ¼” scale means that for every ¼” on the plan will account for 1′ of actual length. Some details, like framing layouts or built-in details may be drawn at a scale of 1/8″ or even ¾”.

Any builder will know to look at the key provided on the house plan to determine the scale of the home. Since the blueprints are drawn to scale if any portion needs to be changed the contractor can scale the drawing to determine the right measurements to make the adjustments. The scale of each drawing is usually next to the title, however, there are times when it is called out beneath the drawing or some other place on the page.

Elevations:

Blueprints also generally include four elevation drawings of a home, the front, the rear, and each side. The purposes of these drawings are so that measurements can be taken for any necessary aspect drawn to scale and also indicate what the home will look like upon completion. Elevation blueprints also include ridge heights, exterior finishes, roof pitches, and other design aspects to give a general idea of the finished home. These exterior specifications can also provide details about the home’s exterior architectural styling.

Basement Floor Plan:

Basement floor plans (if provided) show how the foundation and the structural integrity should be built. These plans give further details about the location of footings, load-bearing walls, steel rebar concrete reinforcements, and other structural elements the home requires to support the walls and roof.

Electrical layouts:

Electrical diagrams (if provided) can often be difficult to read which is why the drawings of the electrical layout of a home are often on a separate drawing. By keeping the electrical layout on it’s drawing the electrician can begin wiring the home without reading through the entire building floor plan. Electrical diagrams usually include a legend or Key on the page that explains what each symbol represents. From this diagram, the electrician can determine the location of electrical outlets, fans, fixtures, light fixtures, etc. Electrical diagrams may also include legends for heating systems, door swings, and sizes, or even to specify certain finishes.

Framing Drawings:

Like every other drawing, the framing drawings (if provided) are also drawn to scale. Framing plans include the basic skeletal structure of the home. Floor joist locations, walls, and roof trusses are the overall details of these plans. Generally, locations of each student are not included, due to a recognized universal building code. However, in some cases, there are instructions for particular wall construction methods.

Plumbing and mechanical systems:

Since stock house plan blueprints are sold throughout the 50 states, regional preferences and climatic variances dictate different mechanical systems and, as such, this information must be obtained locally. Typically only plumbing fixture locations are provided, but this information is ample for the contractor to install a plumbing system. However, you may want to have the heating subcontractor provide a duct and register layout for your review prior to construction. Your local utility company also may offer various services to you in sizing a system for your new home.

Cross sections and details:

Overhead views or floor plan views of the structure provide detailed information about wall lengths and room dimensions to do not fully provide enough information for successful construction of the home. Therefore in most cases, a cross-section of the home is included in a set of house plans. A cross-section of a home is a drawing of the completed home as if it were sliced in half. This part of a home plan provides the builder with an even better understanding of the relativity of floor heights, and rafter lengths among other structural elements of the home.

Plot Plan:

A plot plan are comprehensive drawing of the site location or lot on which a new home is to be built. Plot Plans are drawn to determine the placement of the home on the chosen building lot in reference to the property boundaries, topography, and house layout. Plot dimensions are normally recorded by a surveyor, and are used to determine the exact location and positioning of the selected home in relationship to the chosen lot. Plot plans will typically include the location of utility services, setback requirements, easements; locations ways, and walkways. In some cases, a topographical map may be included that will supply the architect or builder with critical data on the slope and terrain of the lot he or she is designing a home.

Since plot plans are prepared based on the exact size and dimensions of the house to be built and how it will fit into a selected lot location they are not normally included in the purchase of stock floor plans, however, plot plans can be drawn by a local professional draftsman, architect or engineer once a lot is chosen.

So, now that you know how to read a Blueprint you need to understand the differences between the different styles! See our information on How to choose the Right House Plan.