Home Addition cost in Boise, ID
Boise, ID · updated August 2026
$107,900
Typical local cost
$46,300 – $287,800
Typical range
- per sq ft of added space
- $200 – $450
- Permit
- Yes
- Typical timeline
- 3-6 months of construction
Installed, local pricing
$800 – $6,000 in fees
3-6 months of construction, 6-14 months including design and permitting
Boise runs +3% against the U.S. average · data confidence Medium · modeled estimate, not a quote
Most Boise homeowners pay around $107,900. The local adjustment for this trade is x1.028 — driven mainly by Ada County labor rates and 90% exposure to local code requirements.
Estimate your Boise job
Priced with this market's cost index, so the calculator, the size table and the ranges on this page all agree.
Square footage
180 sq ft
- With waste allowance
- 198 sq ft
- Square yards
- 20
- Perimeter (per area)
- 54 ft
- Square meters
- 16.72
Estimates only. Local pricing, site conditions and code requirements change the real number.
Cost by project size
Generated from the same unit pricing the calculator uses.
| Project size | Estimated range |
|---|---|
| 200 sq ft of added space | $40,000 – $90,000 |
| 275 sq ft of added space | $55,000 – $123,800 |
| 325 sq ft of added space | $65,000 – $146,300 |
| 425 sq ft of added space | $85,000 – $191,300 |
| 575 sq ft of added space | $115,000 – $258,800 |
Based on Boise pricing of $200–$450 per sq ft of added space.
Where the money goes
- Labor
- $59,300
- 53% of median
- Materials
- $48,600
- 44% of median
- Permit & fees
- $3,400
- 3% of median
Boise project costs+3% vs U.S. average
Based on Ada County labor rates, local material logistics and permit-fee posture for this trade.
What the project looks like start to finish
Typical sequence for this scope. Timing varies with contractor backlog and plan-review queues.
01
Planning & quotes
Scope, material choice, contractor selection
02
Permit application
Filed with City of Boise building department
03
Materials & staging
Order lead time on non-stock materials
04
Installation
3-6 months of construction, 6-14 months including design and permitting
05
Inspection
Foundation / slab inspection, Framing and sheathing, Electrical, plumbing and mechanical rough, Insulation and energy, Final building inspection
06
Closeout
Final sign-off, warranty and documentation
Boise labor intelligence
What the trade charges here, and how much of your price it is.
Loaded hourly rate
$72–$93
Structural crews in Ada County · 0% vs U.S. ($82/hr)
Typical crew
4 × 22.5 days
On-site time for a typical addition job here.
Labor in the price
$59,300
55% of the median — the rest is material, disposal and permit.
Because labor is 55% of this job, Boise wage levels move the price far more than material prices do. A quote well under this labor figure usually means a smaller crew, a longer schedule, or unlicensed help.
Basis: Hometriva labor model: national structural crew rates adjusted by the Ada County labor factor (x1.000). · BLS Occupational Employment and Wage Statistics, Hometriva methodology
Why Boise differs from the national average
The local delta, broken into dollars by driver.
Code and inspection load+$2,925
Home Addition carries 90% exposure to local code requirements, and this jurisdiction's review load indexes at x1.03.
Basis: Decomposition of the modeled Boise median against the U.S. median for this scope. · City of Boise building department, Hometriva methodology
Boise vs Idaho vs the U.S.
Change the inputs, see your number
The same local model, run against your job instead of the average one.
Simulated home addition in Boise
$111,300
Likely range $49,700 – $291,200
Simulated from the same local model as the numbers above — it changes the inputs, not the pricing method.
What makes the number move
- Added square footage and whether it is one or two stories
- Foundation type and site conditions
- Extending or adding HVAC capacity
- Zoning setbacks, lot coverage and impact fees
- Flood zone elevation requirements
Who issues each permit
Tracked per discipline — the building permit issuer is not always the body that reviews electrical, plumbing, zoning or fire.
| Discipline | Issuing authority |
|---|---|
| building | City of Boise building departmentModeled estimate |
| electrical | City of Boise building departmentModeled estimate |
| mechanical | City of Boise building departmentModeled estimate |
| plumbing | City of Boise building departmentModeled estimate |
| zoning | City of Boise building departmentModeled estimate |
| fire | City of Boise building departmentModeled estimate |
Permit requirement in Boise
Yes — a permit is required for home addition in Boise, ID. The work must be inspected before it can be closed out, and a licensed contractor generally has to pull the permit.
- Permitting authority
- City of Boise building departmentModeled estimate
- Permit fee
- Estimated allowance $800–$6,000Modeled from comparable fee schedules — not an official quoted fee.
Inspections
- Foundation / slab inspection
- Framing and sheathing
- Electrical, plumbing and mechanical rough
- Insulation and energy
- Final building inspection
Local conditions that change this job
Only the exposures that materially affect home addition.
Design wind speed exposure
Moderate52/100
Named-storm exposure
Moderate42/100
Flood zone exposure
Low24/100
Fast population growth has tightened contractor availability, and wildfire-adjacent foothill neighborhoods carry additional material expectations.
Owner-occupied homes
60%
Owner-occupied share of the housing stock, which drives how much of this work is homeowner-funded versus landlord-funded.
Households in market
94,274
Approximate household count in Boise, used to size the contractor pool for this trade.
Permit activity index
x1.00
Relative permit volume and fee load versus the national baseline.
Nearby market comparison
| Market | Local factor | Median | Per sq ft of added space |
|---|---|---|---|
| Boise (this page) | x1.028 | $107,900 | $200 – $450 |
| Salt Lake City | x1.081 | $113,500 | $200 – $500 |
| Spokane | x1.083 | $113,700 | $200 – $500 |
| Portland | x1.292 | $135,700 | $250 – $600 |
What Boise homeowners actually paid
Real reported invoices from this market, aggregated. Add yours — it takes 20 seconds and no personal details.
Quotes homeowners were given in Boise
Quotes run ahead of final invoices. Reporting yours shows the local spread and where there is room to negotiate.
How Hometriva estimates Boise addition costs
Hometriva does not publish invented city prices. The Boise estimate for home addition is produced by this chain, and every input is stored separately:
- National baseline$105,000
Typical U.S. cost for home addition on a single-family home.
- Local labor factorx1.000
Boise-area trade labor rates, weighted at 55% of this job.
- Material factorx1.000
Material and delivery pricing into Ada County, weighted at 45%.
- Regulatory factorx1.031
Local code, product-approval and inspection load, applied at 90% for this project type.
- Applied multiplierx1.028
Blended Boise adjustment specific to home addition.
- Permit component$800 – $6,000
Budgeted separately from the contract price because it is paid to the jurisdiction.
Because labor, material and regulatory factors are weighted per project, home addition in Boise carries a different local adjustment than other trades in the same market.
Reviewed by
Hometriva Cost Data Desk
Maintains the unit-cost baselines, local adjustment factors and material pricing. Reviewed for home addition pricing in Boise, ID.
- • National unit-cost baselines against current trade pricing
- • Local labor and materials factors for the market
- • Material installed-cost ranges and service life
Last reviewed August 2026 · Editorial standards · Report an error
Frequently asked questions
How long does an addition permit take in Florida?
Plan review for an addition typically runs four to twelve weeks depending on the jurisdiction, and that is after the sealed drawings are complete. Coastal and flood-zone properties take longer because of elevation review.
Do impact fees apply to a home addition?
Many Florida counties assess impact fees on added conditioned square footage. The fee is usually calculated per square foot and can add thousands to a large addition, so ask for the fee estimate before design.
Sources
Sources & verification
- City of Boise building department
- Boise permit portal
- Idaho Division of Building Safety
- BLS Occupational Employment and Wage Statistics
Last verified August 2026. Cost figures are modeled estimates based on national baselines adjusted for local labor and material pricing — they are not quotes. Permit rules change; confirm with the building department before starting work.