The cost for a bump-out addition ranges from $10,000 to $43,000, with an average of $27,000. Factors like the room you’re expanding play heavily into your final price.
The cost to add a bump-out addition averages $27,000 for most projects but ranges from $10,000 to $43,000. Overall, you can expect to pay between $90 and $300 per square foot for the cost of a bump-out addition.
A bump-out is a small addition to an existing room in your home, such as the kitchen or a bedroom. It’s not nearly as expensive or time-consuming as a full-room addition and is an excellent option for homeowners looking to create just a little extra space. Bump-outs, also known as “micro additions,” come as small as two feet or extend up to 10 to 15 feet from the house. Before you break out the sledgehammer, review the significant cost factors of a bump-out addition below.
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.
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.
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.
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.
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.
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.
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.
| Bump-out Room Size (Square Feet) | Average Installation Cost* |
|---|---|
| 2x10 | $1,800–$6,000 |
| 2x15 | $2,700–$9,000 |
| 3x10 | $2,700–$9,000 |
| 3x15 | $4,100–$13,500 |
| 4x10 | $3,600–$12,000 |
| 4x15 | $5,400–$18,000 |
* Not including the cost of HVAC, electrical, or plumbing
It’s no shock that adding a bump-out addition to your home is less extensive than a full-home remodel. However, you might be surprised to find out that you will still need plenty of professionals to come together to get this job done. Your local home remodeling company will handle the scheduling, but below are the different pros you can expect to be part of the job.
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 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.
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.
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.
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.
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.
A cantilevered bump-out is a small addition to a house that extends from an existing room outward with no supporting structures, like posts, underneath. These micro bump-outs run from floor to ceiling, are about two or three feet deep, and have several benefits. For one, they save on costs because they don't require any new foundation work since they're anchored to the wall. Another perk is that they preserve yard space.
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.
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.
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.
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.
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.
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.
| Home Remodel | Bump-Out Addition |
|---|---|
| Average cost is $50,300 | Average cost is $27,000 |
| Increases space over the whole home | Increases space in one room |
| Can take between 4 and 6 months to complete | Can take between 1 and 4 weeks to complete |
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.
Bump-out additions are a great way to increase home value without undergoing a complete home transformation. Bump-outs 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. Although bump-outs add home value, they only provide between 30% and 50% ROI.
Bump-outs create more space nearly anywhere in your home, including rooms on the second story. Because they are small expansions, bump-outs don’t connect to the foundation, making these micro-additions faster, easier, and cheaper than a larger renovation project.
In addition, bump-outs allow homeowners to implement some of the top house-selling features, including expanded walk-in closets, renovated bathrooms, and larger windows.
There are some rules regarding how far your exterior bump-out can go. For a cantilever bump-out that avoids the need to provide additional structural support, the limit is typically 24 inches. However, if a footing and foundation are part of the project, a bump-out can encompass a whole room or more. Remember that many residential properties are subject to limits regarding the total house size relating to the size of the lot.
You can add up to two feet of cantilevered space without installing a foundation. Several building codes address these types of bump-outs. Any home addition extending beyond that distance will require some sort of foundation or other, locally approved by building code, support structure. Many building permit applications require approval from a structural engineer for cantilevered structures.
Most bump-out additions take between one and four weeks to complete, depending on the complexity of the project. In contrast, a full home addition timeline can take at least three months to complete. Bump-outs that require additional HVAC, electrical, and plumbing work tend to take longer within that range, while less extensive, smaller projects can be done within a week. Your local home addition pro can give you a rough timeline of what to expect.
Bump-outs enhance existing rooms, and while you might know that you want additional space, you might now know the best way to utilize your additional space. Some options for building a bump-out include:
Adding extra space in the kitchen for a breakfast nook or kitchen island
Adding a walk-in pantry
Extending counter space in the kitchen
Adding a reading corner or window seat with connected bookshelves
Adding additional space to a bathroom to accommodate a bathtub
