How much does a bump-out addition cost?
$85 – $200 average cost per square foot
$5,000 – $35,000 average total cost
Average bump-out cost
A bump-out addition costs $85 to $200 per square foot on average or $5,000 to $35,000 total for labor and materials. The cost to add a bump-out depends on the size, features, and foundation type. A bathroom or kitchen bump-out may cost more if it involves plumbing and electrical changes.
|National Average Cost||$20,000|
|Average Range||$5,000 to $35,000|
Cost data is from research and project costs reported by HomeGuide members.
What is a bump-out addition?
A bump-out addition extends an existing room out by as little as 2 feet or as much as 10 to 15+ feet. Most bump-out additions do not add a separate room, they increase the size of an existing room. This micro-addition typically costs less than other home additions because:
A small bump-out can often be cantilevered from the existing foundation, needing no footings or foundation walls.
Most bump-out additions utilize the room's existing electrical, plumbing, and ventilation.
Some bump-outs can use the existing roof overhang, saving on roofing materials and labor.
Bump-out cost by size
The table below shows the average cost for bump-out additions of varying sizes. Costs are higher for jobs involving the addition or rerouting of electrical, HVAC, or plumbing lines. Larger bump-out extensions also require more extensive roofing and foundation work.
|Room size||Average total cost*|
|2'x10'||$1,700 – $4,000|
|2'x15'||$2,600 – $6,000|
|3'x10'||$2,600 – $6,000|
|3'x15'||$3,800 – $9,000|
|4'x10'||$3,400 – $8,000|
|4'x15'||$5,100 – $12,000|
*Cost for bump-outs not involving electrical, HVAC, or plumbing work.
Cost to bump out a room by type
The type of room you're bumping out plays a significant role in the costs involved.
While most kitchen remodels cost $150 to $250 per square foot, a bump-out may cost less if you are not adding or changing the plumbing or electrical lines. Bumping the kitchen out just 2 feet may offer enough room to improve the room's functionality with an island, more cabinets, or a breakfast nook.
The cost of a bathroom bump-out addition depends on the specific modifications involved. On average, bathroom remodels cost $120 to $275 per square foot total. Bump-out prices fall at the high end when adding and upgrading multiple fixtures. A simple bump-out to fit a larger tub or shower may cost less.
A bedroom bump-out costs $80 to $150 per square foot total on average. Bedroom bump-outs cost less since they don't involve plumbing and may not require any electric or HVAC work. Bumping out to add luxury features like a large, high-end bay window or a custom closet will be more expensive.
Installing a new bay window costs $2,000 to $6,000 for materials and labor.
The average cost to build a custom closet is $1,500 to $4,500 total.
A garage bump-out is often the cheapest type of bump-out addition because there is much less finishing work involved. Most garage extensions cost $60 to $120 per square foot, and most bump-outs fall at the low end of this range as there is less demo involved and the roof typically remains intact.
A dormer addition costs $90 to $150 per square foot and is a type of bump-out used to create a small amount of extra space in an attic. A dormer—a small, roofed addition that projects out from a sloped roof—typically has one or more windows.
Finishing an attic costs $15,000 to $75,000 total on average. Dormers are often part of a larger attic finishing project.
Bump-out cost estimator
Two major factors affecting the cost of a bump-out addition are the size of the addition and the type of foundational support used. Smaller bump-outs cost less and can often be cantilevered off the home's existing foundation. A larger bump-out costs more and requires a concrete foundation and footings.
Other factors that influence the cost include:
Room type – Bumping out a kitchen or a bathroom typically costs more than a living room or bedroom bump-out, since these additions may involve plumbing and electrical work as well as adding new fixtures or appliances. Bumping out a garage often requires much less interior finishing work, reducing the cost.
First floor vs. second floor – A second-floor bump-out addition costs more due to the extra time and safety measures involved.
Features – Depending on the room, a bump-out addition may involve adding new furniture, cabinets, shelving, windows, or wall coverings.
Labor costs for a bump-out addition depend on the room you're extending and the features included. A general contractor charges 10% to 20% of the total construction cost or a $50 to $150 hourly rate to oversee and manage all the details of the bump-out project.
The table below shows the average hourly rates for the professionals that may be involved in your project.
Demolition costs $2 to $8 per square foot. A bump-out typically involves demolishing one exterior wall to expand the room outward.
Construction permits cost $500 to $2,000, depending on the size and scope of the bump-out addition. A general contractor typically handles the permitting.
Depending on the type of room you're bumping out, some or all the following interior finishing costs may apply:
|Finish type||Average cost*|
|Concrete slab cost||$6 – $12 per square foot|
|New flooring cost||$6 – $10 per square foot|
|Insulation cost||$1 – $5 per square foot|
|Drywall installation cost||$2 – $4 per square foot|
|Room painting cost||$1 – $3 per square foot|
|Electrical wiring cost||$4 – $9 per square foot|
|Interior trim cost||$4– $10 per linear foot|
|New cabinets cost||$250 – $600 per box|
*Includes materials and labor.
The following exterior finishing costs apply to make the bump-out addition blend seamlessly with the existing structure:
|Finish type||Average cost*|
|Window installation cost||$500 – $2,000 per window|
|Siding cost||$4 – $13 per square foot|
|New roofing cost||$3 – $6 per square foot|
|Exterior painting cost||$1 – $4 per square foot|
|New landscape installation / planting cost||$15– $45 per square foot|
*Includes materials and labor.
Bump-out addition pros and cons
A bump-out addition is a great way to improve your living space and boost its value without the hefty cost of a full addition requiring excavation, foundation pouring, HVAC work, and more. However, the amount of space you can add with a bump-out is limited and may not meet everyone's needs or expectations.
Bump-out addition FAQs
Is a bump-out addition worth it?
A bump-out addition is worth it to expand and improve the functionality of a space without the major construction work of a full home addition. A bump-out addition adds a small amount of extra square footage, ideal for features like a bay window, mudroom, expanded primary suite, or kitchen breakfast nook.
How long does a bump-out addition take to build?
A bump-out addition takes 1 to 4 weeks to build on average. Small, cantilevered bump-outs require less time to complete than a larger bump-out addition built on a foundation and footings. A bump-out addition involving new electrical, plumbing, or HVAC work will take longer.
How far can a bump-out addition go?
How far a bump-out addition can go depends primarily on how it is supported. Most bump-outs extend 2 to 15 feet. Cantilevered bump-out additions can typically extend 2 to 3 feet maximum. A bump-out addition set on foundation footings can extend as far as local building and setback regulations allow.
Getting estimates for a bump-out addition
When searching for a home addition contractor for your bump-out, be sure to:
Find contractors or firms that specialize in or have experience with bump-out additions.
Get 3 to 5 detailed bump-out estimates with similar details to compare.
Check home addition contractor reviews on HomeGuide and Google.
Ask for references and photos of past similar projects.
Hire a company that has been in business 5+ years and confirm they are licensed, bonded, and insured.
Confirm your bump-out addition complies with all local regulations and with your HOA, if applicable.
Have a contract and warranty in hand before the work begins.
Avoid making large upfront payments, and only pay the final bill when everything is complete.
Questions to ask
Ask these important questions so you can feel confident you're hiring the right contractor for your new bump-out addition:
How long have you been in business in this area?
Are you licensed, bonded, and insured?
What experience do you have with bump-out additions?
How big can my bump-out addition be?
What does this type of addition involve?
What does the estimate include?
What problems tend to come up during a project like this?
How long will this bump-out project take?
Can I live in the house during construction?
Do you handle all the required permits and inspections?