Working With Home Addition Plans

By: Glenn Whitehead



If you're thinking of adding a room to your house, you will, most likely need a set of home addition plans. Traditionally, these have been referred to as blueprints. They are, basically, drawings that show the layout of the home and the proposed changes. If you have never worked with construction drawings, here are some of the terms you will need to be familiar with:

  • Floor Plan-This is the most common type of drawing that comes to mind when people think of home addition plans. Imagine you could remove the roof from your home and, from above, could look down and see the overall layout of the home. You would see where the interior walls divide the rooms and where the plumbing fixtures, cabinets, and appliances are. The floor plan is a drawing of this view. The amount of detail included in the drawing depends on your needs and on the amount of money you want to spend. At a minimum it should include room dimensions, names (kitchen, bath, bedroom, etc...), and the location of permanent plumbing fixtures. When you're doing a room addition, there should be an existing view and a view that includes the proposed new room. Beyond that, the amount of detail is up to you. The more detailed the drawings are, the more control you will have exerted over your project. However, there is no need to spend thousands of dollars on overkill just add another bathroom.
  • Elevations-An elevation is a drawing of the home from the outside. This shows you what the property looks like now or what it will look like now. Elevations are not always a part of residential plans. However, when doing a room addition, you should have them in order to see how the appearance of your home will change. It is likely that you will be required to submit elevations to your homeowners association and/or the local government when applying for a building permit. The purpose of this is to insure that the appearance of your home, after the addition, doesn't violate deed restrictions or jeopardize property values. You should become familiar with the local codes and restrictions before proceeding too far in order to save yourself time, money, and headaches later. 
  • Section/Detail-Section and detail drawings are enlarged pictures that show specific details about individual aspects of your project. A section is meant to show you what a particular item would look like if you cut into it and looked at it from the inside. For example: a wall section shows you how that wall is put together. You would see that the framing is 2x4 studs, the inside is covered with 1/2" drywall, the outside is brick, and inside the wall is 3 1/2" fiberglass insulation. Section drawings may be used to specify the construction of openings in the wall, cabinets, or a fireplace. The possibilities are endless. A detail is similar to a section, but it may not show a cut away or the interior of an object. It may only be an elevation. The purpose of these smaller drawings is to give the contractor specific instructions for how to do a particular phase of the work. Depending on your scope of work, they may not be necessary. But, if you want to be sure thing are done in a specific manner, you will need to include some.
  • Interior Elevation-As you can probably guess, this is similar to the elevations of the exterior of the home we talked about earlier. If you want to see what the interior will look like after the changes, you need an interior elevation. This is usually a view of a particular wall. Perhaps, your room addition is a den with a fireplace and book cases on either side. Some people can visualize the finished product. Others may need a picture. The drawing may include details such as finishes or paint colors. If you're not certain of what you want, I would advise having these done. It's much easier to (and less expensive) to change a drawing than it is to change a wall.
  • Structural Drawings-Home addition plans don't always include structural drawings. But, in the case of room additions, they probably should. As the name suggests, these drawings provide specific instructions as to the structure of the home. They include such things as: The size and grade of framing lumber, the method of tying the new construction to the existing, and the size and quantity of reinforcing steel to be used in a foundation. The drawings may be done by a structural engineer, however, these details are often done by the architect or draftsman. The key difference is an engineer will stamp the drawings and certify that the construction is sufficient and meets industry standards. Structural drawings may be required to meet local regulations or as a condition of acquiring financing. 
  • MEP Drawings-Mechanical, Electrical, and Plumbing or MEP drawings are used to specify the details of each of these trades. In Texas, where I've always worked, you will rarely see them in in a set of home addition plans. However, the practices and requirements may vary in other regions of the country. These drawings outline such things as pipe, wire, and duct size and may specify particular fixtures or devices. There will also bea layout or schematic of the work. If MEP drawings are not required, you can probably get by without them in a room addition. Using quality, licensed contractors and having the proper inspections will usually insure that the work is done in satisfactory manner. For helpful tools in selecting the right contractors and writing contracts, check out our DoIt Yourself Contractor Kit.
  • Specifications-Specifications or specs are simply written documents that coincide with your home addition plans to outline specifically how you want your project done. They can include everything from the bidding process and the amount of time allowed to complete the work to specific paint colors and brands of appliances. In large commercial jobs, the spec book may be 3-4 inches thick with hundreds of pages. For a residential room addition, this isn't necessary. It is, however, necessary that you have some sort of specs. They can be written by your architect or draftsman and included with the plans or you can write them yourself. Either way, you should have a lot of input into the process. This is where you insure that you get what you want out of the job. The specs should be written before you begin the bidding process and should govern the project. The terms of all of your construction contracts should be drawn according to the home addition plans and specs.
When beginning the process of having a set of home addition plans done, I would recommend taking the same steps you use in choosing a contractor. Try to get a recommendation from someone you know, check references, and talk to 2 or 3 different people. Architects are just like any other trade. There are good and bad. Take the proper precautions to be sure you get a good one. Using someone that is local and has knowledge of local codes and requirements is always a good idea. These steps you take in the beginning will determine the results in the end.


Home addition plans are just a part of the construction package. For more insight and advice on documenting and specifying the details of your project as well as Fill-In-The-Blank contracts and other critical forms

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