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How Much Does a Home Addition Cost? (2026 Guide)

Home additions average $100–$300 per sqft in 2026. A 400 sqft bedroom/bathroom addition costs $80,000–$150,000. Type, size, and whether you're going up or out are the main cost drivers.

Updated Mar 2026Home & Energy$80K–$200K
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Addition Cost Breakdown

Addition TypePer SqftTypical TotalNotes
Bedroom$100–$180/sqft$25,000–$90,000No plumbing; simpler
Bathroom$150–$250/sqft$30,000–$75,000Plumbing adds cost
Master suite$150–$280/sqft$60,000–$140,000Most popular addition
Family room$100–$200/sqft$30,000–$100,000Vaulted ceilings add cost
Attached garage$50–$100/sqft$20,000–$50,000Unfinished; no HVAC
Sunroom$80–$180/sqft$15,000–$54,000Cheaper than full addition
ADU / in-law suite$150–$300/sqft$60,000–$200,000Full kitchen, bath; rental potential
How Costs Compare
13%
20%
19%
13%
10%
19%
Bedroom 13%
Bathroom 20%
Master suite 19%
Family room 13%
Attached garage 6%
Sunroom 10%
ADU / in-law suite 19%

Pro Tips for Addition

Building out is cheaper than building up — Adding a second story requires reinforcing the existing foundation and costs 20–40% more per sqft than a ground-floor addition.
Budget 10–20% for surprises — Hidden issues (rotted sill plates, outdated wiring, unexpected plumbing) are found in 80% of additions. Do not plan a tight budget.
An ADU can pay for itself — An in-law suite costing $80,000–$150,000 can generate $12,000–$24,000/year in rental income — paid back in 5–10 years in most markets.
Hire an architect before a contractor — A $2,000–$5,000 architectural plan saves far more in contractor errors and ensures your addition matches your home's structure and style.

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Bump-Out vs Full Addition

TypeCost RangeBest ForPermit Required
Bump-out (under 10 sqft)$3,000–$10,000Expanding a single roomSometimes
Micro addition (10–100 sqft)$10,000–$40,000Bathroom, breakfast nookYes
Standard addition (100–400 sqft)$40,000–$120,000Bedroom, family roomYes
Large addition (400+ sqft)$100,000–$300,000+Master suite, ADUYes, plus structural engineer
Second story addition$100,000–$350,000Maximum space gainYes, complex

Frequently Asked Questions

How much does a home addition cost per square foot?▼
Home additions run $100–$300 per sqft fully finished depending on type and location. Simple bedroom additions are on the low end. Master suites with luxury finishes and ADUs are on the high end.
Does a home addition add value?▼
Yes — a well-done addition typically adds $0.50–$0.85 in value for every $1 spent. ADUs and master suites have the highest ROI. Adding a 4th bedroom to a 3-bedroom home can add significant value in family-oriented markets.
How long does a home addition take?▼
A standard 400 sqft addition takes 3–6 months from permit approval to completion. Permitting alone takes 2–8 weeks. ADUs and complex additions can take 6–12 months.
Do I need a permit for a home addition?▼
Yes, always. Home additions require building permits, and most require architectural drawings. Working without a permit can result in fines, forced demolition, and serious problems when selling.
Related Calculators
Kitchen RemodelBathroom RemodelBasement FinishingSunroom
📊 Data Sources & Methodology
Cost data from HomeAdvisor, NAHB (National Association of Home Builders), and general contractor surveys. Regional pricing data from building permit records. Updated March 2026. Learn more about our methodology.