How Much Does a Home Addition Cost?

The ultimate way to add large amounts of fully usable space to your home and enhance your house's resale value is to build a home addition. The typical home addition cost ranges between $22,000 and $81,000, but the cost could rise past $100,000 depending on material, labor, the addition size, and where you live.

How Much Does a Home Addition Cost?

Average Cost

The average national cost of a home addition is around $50,000. Adding a bathroom to that space involves plumbing and more electrical work, which will considerably increase the total average by thousands of dollars depending on the size and amenities of the bathroom.

Low Cost

Some lower-cost home additions with few or no expensive services that require extensive electrical and plumbing work and builder-grade materials include small bump-outs, porches and decks, and dormers that cost about $4,500 (or less) up to $10,000 on average.

High Cost

Higher-cost home additions with extensive electrical and plumbing work and higher-grade materials include garages, in-law suites, and modular rooms, with average costs from $25,000 to over $100,000. A second-story addition is also considered high cost because it involves extensive roof work and averages about $300 to $500 per square foot.

Factors That Increase Home Addition Costs

Size

The size of the addition is a significant determinant of the total cost of the addition. The average price of an addition, including materials and labor, can cost between $80 to $200 per square foot, though as noted, a second-floor addition is considerably more per square foot.

Type of Addition

The purpose of the addition often changes its price. A room addition, for example, will cost less than an addition that will operate as a separate apartment. Unlike full-size additions, room additions do not have expensive services such as full or even half bathrooms, and they have decreased heating and cooling needs, fewer windows and doors, and more straightforward electrical work. Here are some average costs by type of addition.

Electrical Work

Electrical work is necessary for even the most basic type of home addition. Electrical codes provide minimum requirements for lighting and outlets. When home additions become large and more complicated, the electrical bill increases exponentially.

Installing specialty spaces like a home theater, home office, or gym can drive up the home addition cost. Adding features to other rooms, such as electric radiant heating under a bathroom floor, may also increase the price.

Plumbing Work

Much like electrical work, plumbing work is done by licensed professionals—the more plumbing work, the higher the overall cost of the addition. Plumbing work must be tied into the existing plumbing in the main house. 

Bathrooms

Adding only a bathroom to your home can cost about $35,000. Adding a larger bathroom of about 100 square feet with luxury amenities can cost $90,000. Other materials like porcelain tile or natural stone are expensive per-square-foot materials not found in other parts of the home.

Adding a bathroom into a home addition substantially adds to the overall cost. For example, adding a primary bedroom addition (which costs about $62,000) will cost an additional $40,000 to add a bathroom into the space.

Location

The area or location where you want the addition built can also affect the cost. For example, will the addition easily access current features like HVAC systems, electrical lines, and plumbing? If so, that could bring the costs down a bit.

Labor

Any size addition requires a lot of labor. Here are some average costs to give you a general idea of what to expect depending on what type of addition you want.

• General contractor: Fee is typically 10% to 25% of the total project cost
• Architect: Fee is typically 5% to 20% of the total project cost
• Carpenter: $75 to $100 per hour
• Excavation and demolition: $500 to $10,000 (includes permits, site prep, equipment, etc.)
• Electrician: $40 to $100 per hour
• HVAC technician: $50 to $100 per hour
• Plumber: $50 to $200 per hour
• Roofer: $40 to $80 per hour

Permits and Zoning Laws

Zoning laws may require permits and associated costs to pay for those permits. You can expect permit costs from $200 to $3,000, depending on the municipality and the work required, ranging from small projects like adding or removing a wall or pricier projects, such as water drainage, septic system, electrical wiring,

Factors That May Lower Home Addition Costs

Limit the Size

Consider if you need all of the intended space and pare down any unnecessary space. For example, decreasing the size of a living area by a third will lower the addition cost.

Build Attic Space Into a Second-Story

Converting an attic space into a second story is usually less expensive than building outward since no foundation work is needed. If you can keep the existing roof, these expenses remain relatively manageable.

Be Flexible

Remain flexible about scheduling for possible discounts. Remember that spring is usually the prime renovation and remodeling season.

Supply Your Own Materials

Source some of your materials to eliminate contractor markup charges. Be sure to discuss this well in advance with your contractor. Contractors generally won't allow the client to supply building materials like lumber, plumbing, or concrete, but it's common for clients to supply smaller items like bathroom fixtures.

DIY Finish Work

Doing much or all of the finish work, like painting after completion, eliminates labor charges and contractor markup fees. As with supplying materials, discuss this with the contractor well before the project starts. Doing DIY work at the end of the project rather than in the middle ensures that you won't slow down the project.

Resist Unnecessary Changes

Resist the urge to make capricious or unnecessary changes. Changes always drive up the cost of an addition; do so only when necessary.

How to Pay for a Home Addition

When thinking about how to pay for a home addition, outside of tapping your savings, consider taking out a loan, establishing a line of credit, refinancing your mortgage, or taking out a second mortgage.

Home Improvement Loan

Home improvement loans are like a standard personal loan; you borrow a lump sum and make monthly payments over time. These loans usually have a higher interest rate but are less expensive than a credit card. These loans are generally easy to obtain but not the cheapest option. Also, a personal loan will have a shorter repayment term than other options, which usually increases monthly payments.

Home Equity Loan

A home equity loan is a second mortgage. You borrow money using your house as collateral. These loans have fixed interest rates and a set repayment period, similar to a home improvement loan. If you itemize your taxes, the interest you pay may also be tax-deductible.

Home Equity Line of Credit

Similar to a home equity loan, you establish a line of credit that is borrowed against the equity you have in your home. It acts like a credit card. You borrow against it, make payments, and up to the established line of credit. This option is not a fixed interest rate; it's variable, and you have a fixed time frame to repay the loan. Most borrowing windows are about 10 years. Its biggest downside is if you haven't owned the home long, you may not have accumulated much equity in your home yet.

Refinance Your Mortgage

When refinancing your mortgage, your loan to your original lender is paid off, and a new lender sets new loan terms, with a new interest rate, a new payment term, and some closing costs.

If you have enough equity in your home, you can apply for a cash-out refinance to borrow more than your original mortgage and get the difference in cash at closing to pay for your home renovation costs. This option only works if you've built significant equity in your home, and it's limited to up to 80% of the home's value.