How to Read Blueprints
The original drawings were once very valuable because they represented hours and hours of hand drawing. Today house plans are most commonly created using computer aided drafting & design software (CADD or CAD). If the originals are accidentally destroyed the plans are on file and may be reprinted and original drawings are now referred to as reproducibles. In the pre-drawn plan industry, this means that the purchaser has a license to reproduce as many copies as needed to build one home from the plans. Minor changes to personalize the home plan may be made on these sheets but realistically, they are not easily erasable and substantial changes may require that they be redrawn. Also available today are PDF files that are essentially reproducibles that can be sent electronically and CAD files that you can have a local professional revise. Reproducibles and PDF are more expensive than print set packages because of the additional flexibility they offer. CAD files offer the opportunity for major changes to be made without having to redraw the entire plan and are consequently the most expense to purchase a license to use.
THE BASICS OF READING BLUEPRINTS
Scale: Home plans are drawn to a scale so that the relationship from one part of the plan to another is correct and understandable. The use of scale allows the depiction of the finished home on a manageable sized piece of paper. The main floor plans are generally drawn to 1/4” scale; this means that every 1/4” on the plan equals 1’ in actual length. Other details for framing layouts or built-in cabinetry may be drawn at a larger scale such as 1/2” or even 3/4”. The scale of each drawing is usually called out beneath the drawing or somewhere on the page, generally adjacent to the sheet title.
Elevations: Elevations are a two dimensional view of the homes exterior. Each elevation represents one side of the house. Plans will include front, rear, and both side elevations. The elevations depict ridge heights, positioning of the final grade of the lot, exterior finishes, and roof pitches and other details as may be necessary to give the home its exterior style.
Foundation Plan: The basement or foundation plan delineates the location of bearing walls and structural beams that will support the house above. It will also identify locations of footings, steel reinforcement placement, placement or connections and other structural elements that are required to support the loads of the upper floors.
Floor Plan(s): Floor plans provide an overhead view of the walls and rooms of the house. Parallel lines represent the wall thickness and dimensions and are drawn from wall to wall to specify room sizes and construction requirements. The overall room sizes will also be labeled under the room name so adding up dimensions to calculate an overall room size is not required. The floor plan will also locate fixtures like sinks, tubs, appliances, etc.
Sections and Details: Floor plans and elevations don’t always provide enough information on how the home is to be built. Often a section or specific details will be required to explain special conditions more accurately. A section is essentially a view of the home if it were sliced vertically at the location labeled on the plan. This allows you to view the home from the inside and understand the spatial and structural characteristics a little better.
Site Plan: Site or Plot Plans are drawn to determine the placement of the home on the building lot. A plot plan is an overhead view of the construction site and the home as it sits in reference to the boundaries of the lot. Pre-drawn house plans usually do not include plot plans since they are drawn specific to the site where it will be built.