How Much Does a Bump-Out Addition Cost? [2025 Data]

Bump-Out Addition Cost by Type of Room

Choosing the room to build a bump-out addition can be a fun but difficult decision. Bump-outs offer the opportunity to have additional space without having to undergo a significant renovation. The location of your bump-out addition can impact the total cost, as some locations might need plumbing, electrical work, and HVAC installation. 

Kitchen

Extending your kitchen by adding a bump-out addition to your home often costs more than most other types of add-on structures due to the potential for more electrical and plumbing work. The size of the addition and what it will accommodate are the most significant price factors. If moving or adding plumbing and electrical mechanicals is necessary, expect the addition to cost between $100 and $300 per square foot. 

Bathroom

Like a kitchen addition, the cost of a bathroom bump-out will depend mainly on its size and the inclusion of mechanical services like plumbing, electrical, and HVAC. If you're simply adding a small bump-out to include a larger shower, the price will likely be on the lower end of the scale. However, when moving or adding a substantial amount of mechanicals, expect to spend between $200 and $300 per square foot to cover the total cost of the job. 

Bedroom

When plumbing isn't part of the project scope, the costs of adding a bump-out to add square footage to an existing bedroom or creating a new one tend toward the lower end of the pricing scale. Typical per-square-foot prices range from $90 to $200 for a bedroom bump-out, depending on the complexity of the addition. Costs could be higher if your home addition plans call for adding extensive or elaborate windows.  

Garage

Extending your garage space by adding a bump-out can be simple or quite elaborate. However, you'll most often avoid costly finishing and trim work, and mechanical and electrical work is minimal. Most garage bump-out additions cost between $90 and $120 per square foot to complete. 

Attic

A dormer addition is the perfect option if you want to add some additional space to your attic. The cost to add a dormer averages $12,000, or $115 per square foot. This small and roofed addition helps maximize your space without breaking the bank.

Bump-Out Addition Cost by Size

The size of your bump-out addition directly impacts the overall cost—the larger the space you add, the higher the price tag. Larger bump-outs need additional foundation and roofing work, which all adds to your total. Below are the costs you can expect for your bump-out addition per size. 

* Not including the cost of HVAC, electrical, or plumbing

General Contractor Costs

Even though bump-out construction isn’t as intensive as a whole-room addition, we recommend working with a professional. The cost to hire a general contractor or local home remodeling pro is often a fee of about 10% to 20% of your project’s total cost. Contractors don’t often charge by the hour for large-scale projects like home additions. 

Plumber Costs

If your bump-out addition includes adding or moving plumbing, including supply and drain lines, expect to spend between $45 and $200 per hour, or roughly $1,500 to $6,100, for your local plumber to install the pipes and fixtures for a bathroom add-on.  

Electrician Costs

Depending on the size and location of your bump-out, you may need to add additional wiring for lights or a ceiling fan. Expect to pay between $50 and $100 per hour for a licensed electrician to perform the work.

Bump-Out Additional Cost Factors

After you’ve decided where and how big the bump-out addition will be, you still have some more decisions to make that will adjust your overall cost. 

Foundation

Depending on the size of your bump-out, soil conditions, standard building code, and any local restrictions or requirements, additions may need to rest on a concrete slab, stem wall, piers and beams, or over a crawl space. 

There are a few methods of adding a foundation to support your bump-out addition that's too large to cantilever from the house. The average cost range for installing a foundation is between $4 and $16 per square foot, but it may be more if heavy earthwork is necessary or if the soil conditions are particularly poor.

Permits

All home additions, no matter how small, require a building permit, which costs between $460 and $2,900. Even if you only create a two-foot bump-out, acquiring a permit is important before any work begins. Additions made without the proper permit run the risk of having home insurance claims denied in the future.

Windows

Window installation costs between $575 and $1,500 per window, depending on your chosen size and style. Large picture or bay windows and skylights will land you on the higher end of prices.

Interior Bump-Out Finishing

You’ll likely want to continue the existing wall and floor styles into the micro expansion. Expect to spend $2 to $6 per square foot on the cost of painting and $3 to $22 per square foot on flooring.

Exterior Bump-Out Finishing

Once completed, a bump-out will likely need siding, which costs between $3 and $11 per square foot. If you need to extend your roof to cover the addition, the cost is $50 to $85 per running foot.

DIY Bump-Out Addition vs. Hiring a Pro

Adding a bump-out addition to your home as a DIY project is a huge undertaking and is not recommended. While highly skilled DIYers may be up to the task for much of the project’s overall construction, mechanical installations such as plumbing, electrical, and especially HVAC are always best left to the experts. 

Even adding a small bump-out addition to your home can be a highly disruptive project in the house. Hiring a local home addition company removes you from the hassle of gathering permits and being present for inspections. It will also minimize the time it takes to complete the work so you and your family can start enjoying your space sooner. And most importantly, hiring a pro will ensure that your bump-out is built correctly and safely, which is always a top priority.

Home Remodel vs. Bump-Out Addition 

With the average cost of a home addition hovering around $50,300, it’s no wonder why homeowners are quick to consider a bump-out addition for some additional space. It’s significantly less expensive, and with the right size, you can add just the usable functionality that you need.

How to Save Money on Bump-Out Addition Costs

Building any addition to your home represents a significant financial and time investment. While the project's duration depends mainly on the size and scope of the work, there are a few ways to save some cash to help meet your budget or reduce your dependence on home addition financing. 

• Create your bump-out addition plans to avoid or minimize moving or installing costly mechanical systems like plumbing, electrical, and HVAC.

• If possible, coordinate with your contractor and perform some of the simpler tasks yourself, such as light demolition, debris removal, or painting and trim work. 

• Obtain at least three pricing bids for the project and steer clear of any extremely low estimates, as they are seldom as good of a deal as they appear. 

• Reuse interior and exterior materials when possible, and purchase second-hand materials when it makes sense. 

Does a Bump-Out Addition Increase Home Value?

Bump-outs offer a return on investment (ROI) of between 30% and 50%, so they can potentially increase your home value by a few thousand dollars. 

Bump-out additions are a great way to increase home value without undergoing a complete home transformation. They add additional square footage to spaces in your home, like living rooms, offices, bathrooms, and kitchens, which is always a great value. By adding this square footage, bump-outs increase the home’s functionality, and from the street, they make a house look more appealing.

How Angi Gets Its Cost Data

Home is the most important place on earth, which is why Angi has helped more than 150 million homeowners transform their houses into homes they adore. To help homeowners with their next project, Angi provides readers with the most accurate cost data and upholds strict editorial standards. We extensively research project costs to develop the pricing data you see, so you can make the best decisions for you and your home. We rely on 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. 

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