Generally, building a home addition in the US will set you back between $22,000 and $80,000. This covers the cost of the materials and work for a straightforward addition like a 10-by-10-foot bedroom, a 15-by-15-foot living room or a 20-by-20-foot family room. But if you want something more elaborate, like a second-story addition or a full kitchen makeover, you can expect to pay more. The cost of building a home addition can vary widely depending on a number of factors, such as the size and complexity of the project, the materials used, the location of the property and local labor costs. As a result, providing a specific cost estimate can be difficult without knowing the details of the project.
Again, total costs can vary significantly based on a number of factors. But broadly speaking, here's what you can expect to spend to build out the following types of rooms.
Adding a bedroom costs an average of $200 per square foot. The average bedroom size in the US is about 132 square feet, meaning you can expect to pay about $26,000 for a new, average-sized bedroom. Adding a 12x12 bedroom costs about $11,520–$28,800 on average. A master bedroom suite costs about $21,000–$63,000 on average, depending on the size and extent of the addition, especially if it includes a walk-in closet and master bathroom.
The cost to add a bathroom ranges from $9,000 up to $74,000. On average, adding a basic bathroom with a toilet, sink, and shower can cost between $5,000 to $15,000. However, if the bathroom is larger or includes high-end fixtures and finishes, the cost can be significantly higher, ranging from $20,000 to $50,000 for a bathroom home addition for a 6 by 8-foot bathroom addition.
The cost depends on (a) where the bathroom is located and (b) whether or not you'll need to add square footage to accommodate it. Adding a bathroom to an accessible place with existing plumbing—a laundry room, for example—will cost less than adding square footage and new plumbing.
If significant plumbing or electrical work is required, the cost can also increase. It is important to obtain detailed estimates from licensed and experienced contractors to accurately determine the cost of adding a bathroom to a specific home.
The average cost to build a new garage is about $24,000, but the actual costs can vary significantly. At the low end, a detached, single-car garage with no electricity or plumbing can be built for less than $2,000. On the high end, an attached, three-car garage complete with a loft, plumbing and electricity can cost more than $60,000.
A three-season sunroom costs roughly $80 to $230 per square foot, while a four-season sunroom starts at about $200 per square foot and can be as much as $400 per square foot. The difference is that four-season rooms include HVAC and insulation so they can be enjoyed year-round. Three-season rooms lack insulation, use lower-quality materials and typically have no heating or air conditioning.
At about $21 per square foot, decks are a relatively cost-effective way to increase your living space compared to other additions. For an average 350-square-foot deck, expect to pay roughly $7,000 to $8,000 depending on the materials used and the complexity of the design.