Types of House Additions

Full-Size, Bump Out, Sun Room, and More

There is no such thing as a one-size-fits-all house addition; they come in different styles and types. The smallest addition is the pre-fab sun room--costing in the low four figures. Additions can cost as much as you want--even matching the cost of the main house itself--when you include a second story, bathrooms, special media rooms, or master suites.

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    House or Room Addition

    Room Addition Before & After
    Room Addition Before & After. Copyright Erich Koyama (via Black & Decker The Complete Guide to Room Additions)

    For lack of a better term, this option is just called a house addition or a room addition. Nothing less than one entire new room is added to the house: great room, dining room, or family room. Usually, more than one room is added: bedroom plus a master bathroom or living room plus an extra bathroom.

    Though expensive, with costs rarely dipping below $50,000 in any market, room additions return high value in relation to their cost. The process of adding a room or more to your house is a grueling one. You're basically building a mini-house, complete with all the trappings of a house-build: architect, contractor, permits, wiring, HVAC, plumbing, change orders, and more.

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    Bump Out

    house bump out
    House Bump Out. Copyright Shutterstock via Black & Decker The Complete Guide to Room Additions

    A house bump out is an addition scaled way down. In fact, it's not even a room anymore--it's an enhancement to an existing room. The bump out can add another 50 square feet to your kitchen so that you can squeeze in a kitchen island. Or it can turn a powder room into a bathroom with a shower. Or it can cantilever a few more feet out into thin air to turn a cramped dining area into a comfortable place to eat and socialize.

    Bump outs often lay down a new roofline, employing a shed style or flat roof. Lest you think bump outs are a cost-saving measure, they are and they aren't. The per-square-foot cost is high. But your total square footage is small, so you will save costs over building a full-scale addition.

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    Sun Room

    Sun Room. (c) Sunroom Structures

    Sunrooms have long been the red-headed stepchild of the house addition world, thought of as drafty structures of aluminum and thin glass that are either too cold or too hot. Thus, they never get used.

    Pre-fabricated sunrooms have evolved. For one, you can purchase thermal-resistant glass. For another, the rickety aluminum frames of yore are still aluminum but are far more structurally sound and precision cut for tighter assembly.

    Expect to pay at least $11,000 (with shipping) for a well-made sun room of around 150 square feet.

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    Conservatory. (c) Pioneer Craftsmen

    Isn't a conservatory the place where Professor Plum committed the murder? Perhaps in the board game Clue. But in real life, a conservatory is an addition to the house that mainly showcases flora. The pictured site-built conservatory is from Pioneer Craftsmen, a design, build, renovate firm based in Kitchener, Ontario. Conservatories are a variety of sunroom, but tend to be pricier than sunrooms.

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    Garage Conversion

    Garages are tempting to convert: the box is already there, so how hard can it be just to finish it? If you're turning the garage into a general living space, the wiring and number of outlets already in place can usually be extended. Some garages already have drywall on the studs, leaving one less task to do. But garage conversions come with some serious downsides. For one, it's tough to make it blend in with the rest of the house on the outside, and for it to flow on the inside. HVAC systems need to be ducted to the garage. Garage conversions have low resale value, and houses with no garages are harder to sell. Finally, consider how you will garage your car with no garage. Leave it in the open? Build a carport?