How Much Does a Bump-Out Addition Cost?

Typical Range:

$1,700 - $18,900

Find out how much your project will cost.

Cost data is based on research by HomeAdvisor.

Updated October 10, 2022

Written by HomeAdvisor.

On average, it costs between $85 and $210 per square foot to bump out a room. But this depends on the length and depth of the addition. Bumping out a room adds extra square footage and value to your home for less than a standard home addition. The cost savings occur because the size of the additions is typically smaller, and there’s no need for extra support or foundation construction.

Average Cost to Bump Out a Room

Average Cost High Cost Low Cost
$190 $210 $85

What Is a Bump-Out Addition?

Bump outs are smaller extensions than full-blown additions, and they're always an extension of an existing room rather than a completely new room. Bump outs extend an existing space, and range from 2 to 15 feet wide, so they can easily add significant space to your home. 

People commonly bump out a kitchen for extra counter space, floor space, or to comfortably fit a dining area. Others opt to bump out a bedroom to provide a walk-in closet or to accommodate a new family member. Mudrooms are another popular bump-out option. Building a mudroom costs $8,000 to $16,000. But, consider that a typical small, 50-square-foot mudroom would only cost $4,500 to $10,000 as a bump out. 

Because bump outs are expansions rather than additions, they cost significantly less than the price of building a new home addition. That’s because it requires fewer materials and no additional heating and cooling. Plus, if the bump out cantilevers off the existing joists, you also save on the cost of laying a new foundation and everything that goes along with that, including excavation and grading. House framing costs are also substantially lower, as only a small area requires framing for a bump out. 

Cost to Bump Out a Room by Size

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 2-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 3-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. 

Room Dimensions Square Footage Price Range
2 x 10 feet 20 square feet $1,700 – $4,200
4 x 10 feet 40 square feet $3,400 – $8,400
2 x 15 feet 30 square feet $2,500 – $6,300
3 x 30 feet 90 square feet $7,650 – $18,900

Factors That Influence the Cost to Bump Out a Room

Size is the main factor that influences the cost to bump out; most pros price per square foot. The cost of bump outs compared to the cost of full home additions is less because you don't need to worry about extra insulation, plumbing, electrics, lighting, foundation, or supports. But there are other costs that add to your total budget for a bump out.

Finishing the Space

Once the bump-out construction has finished, you've got to finish the space before you can outfit and furnish it. This adds to the total project cost.


In most cases, installing new flooring costs $3 to $22 per square foot. However, there are loads of flooring options, and you'll want the flooring to match the existing space. But this could also be a good time to install new flooring in the whole room. For bump outs that are their own space, like a home office, laundry room, or craft space, you have more flexibility with flooring choices. On a tight budget, laminate flooring is a good choice. For warmth, carpet or hardwood is the better option. In bathrooms, go for tile flooring. 


As well as flooring the bump out, you'll also need to decorate the bare walls. Just like with the flooring, if the bump out needs to match the larger room, you have limited options unless you plan to update the entire room’s look, which could save you money in the long run. For example, when the bump out is ready for finishing, it's a good opportunity to redecorate as part of the cost to remodel a living room, rather than trying to match the bump out to the existing decor, then remodeling the whole thing in a few years.

Here are some common decorating additions and their associated costs.


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. 


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

Outfitting the Space

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.

Find a Pro for Your Bump-Out Addition
Find a Pro

Kitchen Cabinets

If you've decided to extend your kitchen and you need some 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.

Window Seat and Bookcase

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 have 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, aside from getting a plush, comfortable window seat or armchair, you'll need to think about installing a bookshelf. 

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, so 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. You'll also need really 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 a lot of 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, or you can purchase and install pre-made units that you can configure to your exact needs. And don't forget the desk. For most crafts, you need a large, clear surface to work on.


If you've increased the size of your bathroom because you want to add a nice tub, you'll need to budget for the cost of the 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. Additionally, these are so heavy that you may not be able to locate them in the bumped-out area.

DIY vs. Hiring a Pro to Bump Out a Room

Bumping out a room isn't a job for an amateur. If you get it wrong, you can cause extensive damage that will cost you significantly more to repair than the bump out would've cost to begin with. It's also a huge undertaking. You're far better off hiring a construction manager or general contractor to take care of the whole project for you. 

If you do want to minimize costs, you can take care of much of the finishing yourself, including hanging drywall, wallpapering and painting, adding wainscoting and baseboards, and outfitting the space if you have the time and the skills. But for everything else, rely on the pros.

Get Estimates for Your Bump-Out Addition Project
Get Estimates Now

Frequently Asked Questions

How far can you bump out a room?

If you go with a cantilevered bump out, which is the most common type, you can only bump out four times the depth of your existing joists. Cantilevered bump outs are self-supporting, using the existing walls and joists as their anchor and support. If you want to go out further, you'll need to use a footed bump out, which is built like a deck, supported on deeply seated footings that rest on concrete pads on the ground. For this type of bump out, the only restriction on size and depth is the local building code. So, if you want a micro addition that's larger than what's achievable with a cantilevered bump out, be sure to check local building regulations before you start planning.

Is a bump out worth it?

Yes, a bump out is worth the effort and cost. Even if you're only adding a 2-foot bump out across the whole length of the room, that adds up to significant square footage, which can increase your property value. Consider that, if you add a 2-foot-wide bump out to a kitchen that's 15 feet long, you're adding 30 feet of usable space. If you make the addition 4 feet wide, you'll gain 60 feet. 

Is it cheaper to add on or build up?

If you only want a small amount of extra space, it makes more financial sense to add on in the form of a bump out or even a full addition, rather than adding another story. The cost to add another story is $200 to $500 per square foot, compared to $85 to $210 per square foot to build a bump out.

How much does a kitchen bump out cost?

A 20-square-foot kitchen bump out costs $1,700 to $4,200 for the bump out alone. You'll also need to account for moving or adding kitchen cabinets and countertops and installing new appliances, which could run your costs up another $2,000 or more, depending on the scope of the work.

How much does a garage bump out cost?

A 40-square-foot garage bump out costs $3,400 to $8,400. Because a garage bump out is usually very simple and there's little finishing required, you'll likely pay closer to the lower end of the range. However, if you need to run water or electric to the garage, you'll pay more, as you'll need to hire a pro plumber and electrician to complete these jobs correctly. 

Do I need an architect for a bump out addition?

Yes, you should consult with a local architect when considering a bump out addition. An architect can draw up functional, structurally sound plans that meet local building codes. They'll ensure you've got an adequate opening for the bump out, take into account the need for support beams or the use of existing headers, and the appropriate placement of new doors and windows.