How To Read Blueprints

Time to celebrate! The blueprints for your new house have arrived at last. Not so fast, though. You tear open the package and suddenly, your visions of soaring ceilings, an island kitchen, and sun-drenched rooms have been reduced to a cumbersome sheaf of papers and a mishmash of unintelligible lines, symbols, and notations. Before you proceed, you will need to decipher exactly what those blueprints are saying. This is not only for your own understanding, but so you can communicate clearly with the many professionals you will work with throughout construction, including the lending institution that bankrolls the project, the builder, and the subcontractors. With a little background and concentration, you will be interpreting those pages as if you've been doing it for years. Read on for more information.

What's Included:

Your set of blueprints will consist of several pages, each one of which includes information crucial to the construction of your new house. You should expect the following:

Foundation plan. Indicates the type of foundation — usually a full or partial basement, crawlspace, or slab — and all of the specifications necessary for constructing it, including dimensions and locations for footings.

Framing plan. Indicates how all of the walls should be constructed, including the size of the lumber to be used — usually 2x4 or 2x6.

Floor plans. One for each level of the house, these indicate the sizes and locations of all of the rooms in the house, all the doors and windows, and any built-in elements, such as plumbing fixtures and cabinets.

Roof plans. Includes the details needed for roof construction, including type, pitch, and framing.

Interior elevation drawings. Drawings of a selection of the interior walls.

Exterior elevation drawings. Drawings of all four sides of the house's exterior.

Cross-section drawings. Shows a cross-section view of a particular section of the house from roof to foundation. A cross-section will indicate details, such as ceiling height, ceiling type (flat or vault, for instance), and window and door dimensions.

Detail drawings. Close-up drawings of special details, such as built-in shelving, moldings, and columns.

Window and door schedules. Lists the sizes and quantities of all the doors and windows, both interior and exterior, that will be included in the house.

Electrical schematic drawings. Shows locations of all the outlets, switches, and fixtures. Also indicates which switches operate which lights, and where the electric lines should be run.

Plumbing schematic drawings. This indicates the locations of all the plumbing fixtures and piping.

How to Interpret a Blueprint

No doubt, some of the most interesting pages for you in your blueprints will be the floor plans. But to understand them, you will need to decipher the numbers and symbols that provide the keys to what they say. First, floor plans — and all of the other drawings in a set of blueprints — are drawn to scale, often one-quarter or one-eighth of an inch, meaning every one-quarter or one-eighth of an inch on the blueprints equals one foot in actual size. The simplest method for translating scale measurements into their actual size is to measure them with a scale ruler, which will indicate the conversion directly on the ruler. (Scale rulers are available at any crafts store and at many drugstores). Alternately, you can figure the conversion in your head. On plans drawn to a one-quarter of an inch scale, for instance, two inches equal eight feet of true space. Each page of the drawings should be labeled to indicate what size scale the architect or home designer used when drafting the plans.

Some measurements, such as room dimensions, will be labeled directly on the blueprints with their actual size. These measurements are indicated with dimension lines, which consist of a solid line with a mark at either end. The space between the two marks equals the distance noted next to the line. (Some vertical measurements may also be indicated with dimension lines. A cross-section, for instance, will usually include a dimension line that notes the height of the ceiling in a room.)

You will probably also notice a number of circles, triangles, or hexagons with numbers inside of them. Placed next to windows and doors — and sometimes next to other elements, such as lighting or plumbing fixtures — these notations correspond to those on the window, door, plumbing, and electrical schedules found at the back of the blueprints. These schedules indicate the size and types of the doors and windows to be used, and sometimes even the manufacturer and model numbers, as well.

When reading the floor plans, you will probably notice a few circles with numbers and letters inside of them. These symbols are used to indicate a cross-section of that particular room or space that can be found elsewhere in the blueprints. Often, a single page of the blueprints will include two or three cross-section drawings. The number in the circle indicates which page the cross-section is located on, while the letter notes which cross-section on that page is being indicated. Sometimes, the circle will also include an arrow on one side that points in the direction of the view depicted in the cross-section.

And finally, while the symbols used in blueprints are too numerous to mention, you should be familiar with the most standard. Thick, solid lines are used to indicate full-height walls, while thin, solid lines indicate other built-in structures, such as cabinets, bookshelves, or plumbing fixtures. Thin, dotted lines indicate overhead features, such as wall cabinets in a kitchen or a special ceiling treatment or an archway in the living room.