How to Read House Plans and Blueprints

house plans and blueprints

For the architecture novice, a floor plan can be a daunting thing. It is always surprising to see a space translated into a drawing, but once you understand what the signs and elements represent, they become just as recognizable as the real thing. Here, we’ll cover the basics of reading house plans and blueprints.

A floor plan is created by virtually “cutting” the walls, doors, and windows four feet above the ground and drawing the result without perspective. This type of view, called simply “the plan,” is the view that is used to accurately measure lengths and widths. As the most referenced part of the print, we will cover it thoroughly. Different architects have various approaches to plan drawings, but this is the basic standard found in blueprints.

The walls are drawn as two parallel lines with a black mass in between (architects call this “poché”), and they are typically 6 inches thick for interior walls. Windows are drawn as two thin parallel lines with no poché in between, and doors are drawn in the full open position, typically with a thin quarter-circle representing the space of the door swing.

Dashed lines are used to show important elements that are above the cut line of the drawing, such as cabinets, interior balconies, and low-hanging decorative elements. A large X is often used to indicate that everything in a certain space is “open to below,” meaning it’s on the level underneath and visible from above. Staircases often have an arrow drawn on them to indicate the upward direction, and the front door (along with other doors indicated on the plans) of a house might feature one as well. A small symbol on the drawing, called a North symbol, orients the floor plan to the orientation of the building on the site. This can indicate to the viewer whether or not the windows are appropriately placed in terms of the sun’s daily movement.

After the plan view, there are different perspectives that will be included in the blueprints:

  • Elevation: A side view which is used to determine the height of many parts of the house
  • Section: A cut through used to show the inner workings of a house

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If the drawing has a scale listed in the bottom right corner (ex. ¼” – 1’, which means that every  ¼” on the plans equates to one foot in reality), then you can use an architectural scale ruler to measure anything in the drawing. Shaped like a Toblerone, you can use it to measure at a number of scales, and it can be very helpful when trying to get the lay of the land.

Other blueprints have a graphic scale instead of numeric scale. It is often represented with a sectioned line with small black and white segments that indicate distance. Graphic scales are a great help when the plans are not printed out with the original dimensions, so no matter the size of the plan, you can understand how much a foot, mile, etc. is in the drawing by taking the same length of the line in the graphic scale that represents such dimension and applying it on the drawing.

Blueprints can appear very complicated at first, but remember that all the symbols drawn over a floor plan have explanations in a nearby legend, either on the page itself or an accompanying one.

So, you’ve just learned a little bit about the basics of blueprint knowledge. There is much more information to learn about the nitty gritty details of blueprint planning. If you are truly considering a hands on approach as a working team member in your renovation project, consider taking a blueprint reading course, or at least checking out some instructional videos on YouTube. The more knowledge you arm yourself with, the better your project will become.

How to Read House Plans and Blueprints was last modified: July 24th, 2017 by Shane Reiner-Roth
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