Second Story Modular Additions

Advantages of Second Story Modular Additions

If you are building a second story modular addition, you are most likely doing it to create more living space rather than a separate living unit. The general contractor will turn your one-story into a two-story by removing the roof from your home and immediately setting the new modular second story with its own built-in roof on top.

The speed of modular construction is a tremendous benefit when building a second story addition, since the addition can be set in place within hours after the roof is removed from your existing home. Once the modular addition is in place, the inside of your home is protected from a sudden storm. A site builder cannot realistically protect your home as quickly. Another advantage is that the second story can be finished faster. This means your family can use the upstairs more quickly, even if it must wait to enjoy the downstairs until the remodeling is completed.

Requirements for Second Story Modular Additions

There are two conditions that must be met before you can build a second story modular addition. First, the exterior dimensions of the existing home must be compatible with one of the modular manufacturer’s production sizes. If your home is too wide, a modular will not easily work. If your home has multiple bump-outs, a modular might work, but it may be impractical and expensive. A home can be up to 3-feet narrower than a module, however, and adding a wider second floor can create an attractive, cantilevered garrison colonial look.

The second condition is having an existing home and foundation that are structurally capable of carrying the additional weight, which is substantial. You will need to hire a structural engineer to make this determination. He may give you specific instructions on fortifying the structure or the foundation, which might be unacceptable or too expensive. If you decide to carry out his instructions, the GC will complete them as part of his remodeling. Before the engineer completes his final written report, he will need to see plans of exactly what you are building and receive detailed information from the manufacturer.

Design Issues for Second Story Modular Additions

When designing an addition, you must decide where the stairs to the second floor will be located. You must also determine a location for a chase from the basement to the second floor to carry the electrical wires, HVAC supply and return ducts or pipes, and plumbing pipes for second-floor bathrooms. If the GC is connecting to a forced-air system in the basement, the chase must be larger, since the ducts will take up more space than hot-water lines.

Second Story modular additions can make ranches look like brand new homes.
Second Story modular additions can make ranches look like brand new homes.

The design of the second story elevation must be coordinated with the first-story elevation. The window locations on the second story should be arranged in a pleasing fashion. This decision should be made early in the design process, since the location of the interior partition walls on the second story must be coordinated with the window locations (you cannot put a wall in the middle of a window). In addition, the window style and sizes should be matched as closely as possible to the existing home.

The exterior elevation of all four sides of the finished home must take into consideration any first-story bump-outs or structures. For example, the location of an existing bay window, porch, sunroom, portico, recessed entry, or garage can pose special design challenges. The second story must be planned so that it does not affect either the function or aesthetic appeal of these structures. In some cases, it might be necessary to remove a part of the bump-out or attached structure, such as a garage roof, before installing the second story. If the modular second story will be cantilevered, the overhang can pose additional problems with a first-floor bump-out, such as a bay window.

The exterior siding on the second story must fit with the siding on the first story. Otherwise, the siding on the first story will have to be replaced. If you currently have wood siding, you might need to repaint or restain it to create a color match. Similar coordination issues arise for shutters and other exterior trim details.

If you have a chimney on your existing one-story home, you will need to make it taller to reach above the roof of the second floor. In addition, all trees overhanging the first story will need to be removed.

Material Disposal and Second Story Modular Additions

The actual removal of the existing roof as well as any other materials you are replacing in your existing home, such as the siding or windows, will be a task unto itself. The cost of disposing of these materials will be appreciable.

Most importantly, when you are done building your second story modular addition, it will almost feel like you have just built a brand new home.

For more information about building second story modular additions, see Building a Modular Addition in my book The Modular Home.

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