How Much Does a Bump-Out Addition Cost in 2025?

Average Bump-Out Addition Cost

Bump-Out Addition Cost Factors

The primary cost factors for your bump-out addition are the size and type of room, finishes, and professional labor costs.

Room Size

Size is the main factor influencing the cost to bump out because most pros charge per square foot. On average, expect to pay between $85 and $210 per square foot on a bump-out addition.

While adding just a couple of feet to the width of a room doesn't seem like much, it can add significant square footage to your space. 

A two-foot bump out that runs the length of your 15-foot kitchen adds 30 square feet, which is a 20% size increase. This would give you plenty of room to install a breakfast nook or add a generous kitchen island and space for an extra appliance. A three-foot bump out in a 30-foot living room gives you a whopping 90 square feet of extra space, which is plenty for a small home office, book nook, or craft area. 

Finishes

Once basic construction is complete, you’ll need to finish the space before you can outfit and furnish it, which increases the total project cost.

Flooring

In most cases, installing new flooring costs $3 to $22 per square foot. However, there are plenty of flooring options, and you'll want the flooring to match the existing space. For bump outs that are their own space, like a home office, laundry room, or craft space, you have more flexibility with flooring choices.

Laminate flooring is a good choice for those on a tight budget. For warmth, carpet or hardwood is the better option. In moisture-prone spaces like bathrooms or kitchens, tile is a reliable option.

Walls and Trim

As well as flooring the bump out, you'll need to decorate the bare walls. Here are some common decorating additions and their associated costs:

Windows

Installing windows costs $3,500 to $9,900, depending on the size and number of windows. Most people pay toward the lower end of this range for bump outs. If your bump out adds to a bay or bow window and seating area, expect to pay between $800 and $15,000, all-in, for the cost to install a new bow or bay window, including the window panes and the bump out. 

Electrical

While not always necessary, hiring an electrician costs $50 to $100 per hour. You must hire an electrician if the bump out requires additional lighting, outlets, or a ceiling fan. 

Room Type

Depending on which room you bump out and what you plan to do with the extra space, you'll need to budget for the materials and installation required to appropriately outfit the space.

Kitchen

If you've decided to extend your kitchen and need new cabinetry to fill the space, you'll pay $50 to $750 per linear foot for materials and hardware. Once you add in the price of labor, installing new kitchen cabinets costs $100 to $300 per linear foot for standard stock and up to $1,200 per linear foot for custom cabinets.

Library or Den

Installing a built-in bookcase costs $150 to $1,200 per linear foot, all-in, though the price depends on whether you choose a pre-made unit or a custom design. If your bump out is a bay window or a similar type of light, airy, out-of-the-way space and you'd like to turn it into a reading nook, consider getting a plush, comfortable window seat or armchair. 

Home Office

While a home office doesn't necessarily need anything built in, it does need an appropriate desk, chair, and tech setup if you don't already have them. A setup customized to your needs can cost anywhere from $300 to $5,000. Designing a home office takes careful consideration of your working style and needs, so don't rush into things. If space is truly limited, you could install a wall-mounted fold-up desk suitable for a laptop or tablet. 

If you need something more robust to house your desktop, files, and other work-related paraphernalia, choose a desk with plenty of storage space, maybe with a custom-built hutch to use the vertical space. Add good lighting to avoid eye strain. Installing light fixtures costs between $150 and $800.

Craft Space

If your bump out will become your crafting haven, then just like a home office, you need to customize it to the crafts you love and prioritize good lighting. You could pay anywhere from $100 to $10,000 for a custom craft nook. Most crafts come with many bits and pieces, so plenty of storage is a must. 

You can hire a cabinet maker, get quotes from a local handyperson, or find a nearby carpenter to design custom storage solutions. You can also purchase and install pre-made units that configure to your exact needs. Don't forget the desk—for most crafts, you need a large, clear surface to work on.

Bathroom

If you've increased the size of your bathroom because you want to add a tub, the cost to install a bathtub ranges from $600 to $14,000. If you want the ultimate luxury of a marble or cast iron tub, remember that the sheer weight of these items may mean you have to pay extra to get additional structural support for your bathroom floor. 

Labor

Building a bump-out addition requires the expertise of several pros, so it’s important to allocate a labor budget to cover all the work you need. While some pros charge by the hour, others may prefer to offer a quote for the entire project.

Permits

Even for a small addition, you’ll typically need to acquire a building permit before construction can begin. Building permit costs vary depending on the size of your addition and local regulations but expect to pay somewhere between $400 and $3,000.

Does a Bump-Out Addition Increase Home Value?

A bump-out addition generally increases home value because it increases the total square footage of your home. Bump-out additions are especially valuable when they’re versatile, so potential homeowners can use the space however they’d like. 

Budgeting for a Bump-Out Addition

Building a bump-out addition requires professional expertise and labor, but there are several steps you can take to help your project stay on budget:

• Discuss your budget with your contractor: Before you begin construction, talk to your contractor about your budget's hard and flexible elements. They can help you devise a plan to find materials and finishes that fit your price point.

• Look for green grants: Some municipalities offer homeowner construction grants, especially for environmentally friendly options. Installing double-glazed or triple-glazed windows can improve your home insulation and save on utilities, and you may be able to find financial incentives to support your construction.

• Add finishes yourself: If you’re comfortable with DIY, you can save on total project costs by adding details like painting and trimming yourself.

• Compare quotes: Reach out to multiple home addition builders in your area to discuss quotes for your project.

How HomeAdvisor Gets Its Cost Data

No place is more important than your home, which is why HomeAdvisor connects homeowners with local pros to transform their houses into homes they love. To help homeowners prepare for their next project, HomeAdvisor provides readers with accurate cost data and follows strict editorial guidelines. After a project is complete, we survey real customers about the costs to develop the pricing data you see, so you can make the best decisions for you and your home. We pair this data with research from reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects.