InstaBidsWhat is the cost of garage conversion?
Portland, Oregon, conversion guidance: “Structural: A detached garage may not be up to building code standards for living space. You will need to upgrade any structural deficiencies.”
Source: City of Portland, Portland Permitting & Development, read 6 November 2026.
Portland, Oregon, conversion guidance: “If your project has both a non-accessory kitchen and a bathroom, it may be an Accessory Dwelling Unit (ADU). ADUs are independent of the rest of the dwelling, and they have their own set of permits.”
Source: City of Portland, Portland Permitting & Development, read 6 November 2026.
Context: all "Added other room or converted existing space to other room" jobs
The survey figure below covers all "Added other room or converted existing space to other room" jobs, not garage conversion alone.
$12,000 was the median homeowner survey figure for data years 2021-2023 in the United States. For all jobs in “Added other room or converted existing space to other room”, the American Housing Survey recorded a typical range (middle half of 126 American Housing Survey data points, the United States, 2021-2023) of $4,500 to $50,000.
Updated 2026-11-06
InstaBids is an AI-run marketplace for homeowners and property managers: describe a home job once, by chat or through your own AI assistant, add photos, and get multiple written quotes on the same scope, compared apples to apples, with no phone calls or home visits before you pick.
For homeowners, property managers, landlords and HOA boards.
| What was measured | Median | Typical range (middle half) |
|---|---|---|
| For all jobs in “Added other room or converted existing space to other room”, the American Housing Survey recorded | a median of $12,000 | the typical range (middle half of 126 American Housing Survey data points, the United States, 2021-2023) was $4,500 to $50,000 |
How measured: hired-out finished jobs, survey-weighted, not adjusted for inflation. Source: U.S. Census Bureau, American Housing Survey 2023, data read 6 November 2026.
These figures are estimates from U.S. Census Bureau, American Housing Survey 2023, data years 2021-2023, read 6 November 2026, for the United States. They are not a quote, and they are not a promise of what any contractor on InstaBids will charge. Your price depends on your home, the materials and the contractor. Get written bids before you decide.
- Describe it onceBy chat, or through your own AI assistant, and add photos.
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At a glance
- Off-street parking is not requiredPortland off-street parking ruleCity of Portland, Portland Permitting & Development, read November 6, 2026
- their own set of permitsPortland ADU permit distinctionCity of Portland, Portland Permitting & Development, read November 6, 2026
- mechanical, electrical, and plumbing permitsPortland trade permit typesCity of Portland, Portland Permitting & Development, read November 6, 2026
For your AI assistant
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https://instabids.ai/openapi.json - Start-request link
https://instabids.ai/intake?from=cost-adu-garage-conversion-in-law-suite&utm_source=us&utm_medium=page&utm_campaign=cost&page_type=cost&job=adu+garage+conversion+in+law+suite - Prompt for any AI, with your job
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What garage conversion includes
Portland, Oregon, conversion guidance: “Parking: Off-street parking is not required in the City of Portland. When converting a garage, it's fairly common to remove a parking space and keep the driveway.”
Source: City of Portland, Portland Permitting & Development.
Source read: 6 November 2026.
Where a quote below names a city or county, it is that office's own rule, shown as one example; the permit office for your home may set different rules.
| What the source says | Where it comes from |
|---|---|
| Portland, Oregon, conversion guidance: “Fire separation: Any outside wall within three feet of a property line will need fire-rated construction. This doesn't apply in the case of a property line along a public right of way. There may also be limitations on the allowed eave or rake projections from that wall.” | City of Portland, Portland Permitting & Development, read 6 November 2026. |
On InstaBids, describe whether the garage becomes a room or a separate dwelling in the scope contractors read.
Line items a written bid should list
Portland, Oregon, conversion guidance: “If you choose this package, you'll need to submit any trade permit applications with your plans. The trade permits are mechanical, electrical, and plumbing permits. Any subcontractors doing trade work must sign their trade permit applications.”
Source: City of Portland, Portland Permitting & Development.
Source read: 6 November 2026.
- Portland, Oregon, conversion guidance: “Depending on the scope of work, you may also need structural calculations.”
Source: City of Portland, Portland Permitting & Development, read 6 November 2026.
Include the garage conversion trade work in your InstaBids description so contractors bid on the same scope.
How to compare written bids like for like
City of Portland, Oregon, conversion plan drawing requirements: “Drawings may be handwritten or drawn if they're clear and legible. Text or notes need to be in print handwriting.”
Source: City of Portland, Portland Permitting & Development.
Source read: 6 November 2026.
Ask every contractor to bid in writing on the same line items listed above, then compare the written bids line by line.
On InstaBids, describe the garage drawings once so contractors can base their written bids on that scope.
Do you need a permit for garage conversion?
Portland, Oregon, conversion guidance: “You need to get a building permit when you convert an attic, basement, or garage to a living space (also called a habitable space). Your project might also need electrical, plumbing, or mechanical permits.”
Source: City of Portland, Portland Permitting & Development.
Source read: 6 November 2026.
Describe the garage conversion permit work in your InstaBids scope before contractors write their bids.
Can you do garage conversion yourself, or do you need a pro?
Portland, Oregon, conversion guidance: “If you are a homeowner doing the work yourself, then you can sign the trade permit applications. You can do the electrical work only if you own and occupy the home and are not selling or renting within six months.”
Source: City of Portland, Portland Permitting & Development.
Source read: 6 November 2026.
On InstaBids, describe which garage conversion tasks you intend to do and which tasks contractors should include.
Get written bids
Contractors who take part bid on one written scope card, so nobody visits before you see any prices.
Sources for the figures on this page
- U.S. Census Bureau, American Housing Survey 2023, https://www.census.gov/programs-surveys/ahs/data/2023/ahs-2023-public-use-file--puf-.html, read 6 November 2026. U.S. government work; no endorsement implied.
- City of Portland, Portland Permitting & Development, www.portland.gov/ppd/residential-permitting/home-projects/attic-basement-or-garage-conversion, read 6 November 2026.