As-Built Drawings for Hawaii Permitting: A Big Island Homeowner's Guide
If you just found out your Big Island home has an addition, converted lanai, or extra room that was never permitted, you're not alone — and you're not stuck.
The fix almost always starts with the same document: an as-built drawing.
It sounds technical, but it's really just a precise, to-scale picture of your home as it actually exists today.
County officials, lenders, and appraisers all need one before they'll sign off on unpermitted work, a remodel, or sometimes even a sale.
This guide walks through exactly what as-built drawings for Hawaii permitting involve, when Hawaii County requires them, what they cost, and how to get through the process without unnecessary delays.
Key Takeaways
An as-built drawing documents your property exactly as it exists now — not as it was originally designed or permitted.
Hawaii County's Department of Public Works (Building Division) requires as-built plans to legalize unpermitted additions, conversions, or renovations.
As-built drawings typically include exact dimensions, structural and system locations (electrical, plumbing, HVAC), and site-specific details like setbacks and lot lines.
Unpermitted structures can delay or derail a home sale, since Hawaii's mandatory Seller's Real Property Disclosure requires sellers to note permit violations.
Legalizing older unpermitted work on the Big Island can trigger current code upgrades, such as hurricane-resistant connections or wastewater system compliance.
Costs vary widely depending on survey work, drafting, and whether the county requires upgrades to meet current code.
Starting the process early — before listing your home or planning a renovation — gives you far more options than reacting to a county violation notice.
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↪️ References
What Is an As-Built Drawing for Hawaii Permitting?
An as-built drawing is an accurate, scaled document that shows a structure exactly as it was actually completed — capturing any changes made during construction — rather than how it was originally designed.
This is a standard term across the construction and engineering industry, used the same way whether the project is a single-family home or a federal building.
This distinction matters because older Hawaii County homes are frequently modified over the years without matching paperwork — a garage becomes a bedroom, a lanai gets enclosed, or a carport turns into a workshop.
When that happens, the original blueprint (if it even still exists) no longer reflects reality. An as-built drawing closes that gap by documenting what's physically there today.
When You Need As-Built Drawings on the Big Island
Legalizing Unpermitted Work
If a previous owner or contractor built an addition, converted a lanai, or finished a space without county approval, the Hawaii County Department of Public Works Building Division needs as-built plans to review and legalize the structure through an after-the-fact ("as-built") permit.
This isn't a hypothetical problem.
Hawaii County's Building Division actively investigates complaints about unpermitted structures, and cases can take significant time to resolve — particularly since many unpermitted structures on Hawaii Island are in rural or remote areas that aren't easy for an inspector to simply drive by and check.
Major Renovations or Additions
Before an architect or drafter can plan new construction, they need a precise baseline of your home's current walls, plumbing, and electrical layout — especially if the original blueprints are missing, outdated, or were never filed with the county to begin with.
Property Sales and Refinancing
Hawaii real estate agents are required to disclose known unpermitted structures on listings, and lenders often won't finance a property with undisclosed permit violations.
Resolving this with an as-built permit is frequently a condition of closing, and unresolved violations can delay transactions that are already in escrow.
What's Included in an As-Built Drawing
Exact Dimensions
Precise, on-site measurements of room sizes, wall thickness, ceiling heights, and window or door placements — typically accurate to the inch.
System Locations
Documented routing for electrical panels and circuits, plumbing lines, HVAC equipment, and structural load-bearing elements the county reviewer needs to verify for code compliance.
Site-Specific Details
Property boundary lines, required setbacks, and the location of accessory structures (sheds, ohana units, carports) relative to the actual surveyed lot — not just what the tax map shows.
As-Built Drawing vs. Original Blueprint vs. As-Built Permit
These three terms get mixed up constantly, so here's how they actually differ:
Criteria | Original Blueprint | As-Built Drawing | As-Built Permit |
What it is | The plan drawn before construction, showing intended design | A plan drawn after the fact, showing what actually exists today | The county approval that legalizes the as-built drawing |
When it's used | At the start of a new build | When plans are missing, outdated, or work doesn't match records | When work was completed without prior permits |
Who prepares it | Architect or designer | Licensed drafter, architect, or surveyor | Building Division reviews it; owner/professional submits |
Typical cost driver | Design complexity | Site measurement and drafting time | Permit fees plus any required code upgrades |
Outcome | Basis for the original permit | Documentation submitted with an application | Legal recognition of the structure |
Challenges of As-Built Permitting in Hawaii County
Higher Costs and Fees
Retroactive as-built permits, plus the professional surveys required to produce accurate drawings, typically carry higher costs than a standard new-construction permit.
Hawaii County's own permit fee schedule scales with total project valuation, so the fee itself grows alongside any correction work the county requires.
Stricter Compliance Requirements
This is the part that catches homeowners off guard. County reviewers can require older, unpermitted work to be upgraded to current code before it's legalized.
On the Big Island, that most often means:
Wind resistance: Hawaii County's residential building code requires additional opening-protection measures — impact-rated glazing, structural wood panels, or a safe room — anywhere the site's design wind speed is determined to be 130 mph or greater under Section R301.2.1.2 of the County Residential Building Code.
Wastewater compliance: Dwellings without a county sewer connection must have an individual wastewater system designed by a state-licensed civil engineer. Hawaii state law (HRS §342D-72) requires all cesspools statewide to be upgraded, converted, or connected to a sewer system by January 1, 2050, and Hawaii County's Department of Environmental Management is actively planning sewer expansions and conversion options for the island under its Integrated Wastewater Management Plan.
Flood zone review: If the structure sits in a FEMA Special Flood Hazard Area, a flood plain review packet becomes part of the application.
None of this means legalization is impossible — it just means budgeting for potential upgrades, not just drafting fees.
How to Get an As-Built Drawing and Permit on the Big Island
Confirm what's actually on record.
Contact Hawaii County's Building Division (Hilo or Kona office) or check the county's online permit records to see what's currently approved for your parcel (TMK).
Hire a licensed surveyor or drafter.
They'll physically measure the structure and produce dimensioned as-built drawings that meet county submission standards.
Gather supporting documents.
Proof of ownership, a site plan, and — if applicable — a flood plain packet or wastewater system documentation.
Submit to the Building Division.
Applications go to the Hilo or Kona Building Division office, where staff route them to plan reviewers.
Address any code-upgrade requirements.
If the reviewer flags wind protection, wastewater, or structural issues, resolve these before resubmitting.
Schedule inspections.
Once plans are approved, inspections confirm the physical structure matches the as-built drawings before the permit is closed out.
Keep copies for future sales.
A closed-out as-built permit becomes part of your property's permanent record, which protects you at resale.
Real-World Example
Consider a common scenario on the Big Island: a homeowner in Kona buys a property whose enclosed lanai was converted into a bedroom by a previous owner, with no permit on file.
When the homeowner later tries to refinance, the lender's appraisal flags the discrepancy between the tax record's square footage and what's physically built.
The homeowner hires a licensed drafter to produce as-built drawings of the converted space, then submits an as-built permit application to the Hawaii County Building Division.
Because the original enclosure didn't include proper roof-to-wall hurricane connections, the reviewer requires those upgrades before signing off.
After the corrections and a final inspection, the county closes out the permit, and the square footage becomes officially recognized — clearing the path for refinancing and, eventually, a smoother resale.
This is illustrative, not an actual case, but it reflects the pattern county records and permitting professionals describe repeatedly: measure first, then legalize, then upgrade whatever the code now requires.
Ready to Talk to a Builder Who Knows the Big Island?
If you have land on the Big Island and you're trying to figure out what it will take to build on it, Boom Hawaii Builders can help.
We've built in Hilo, Kaumana, Ainaloa, Keaau, Waiākea Nani, and up to Kamuela. We’ll walk you through the process, give you honest answers about timelines and costs, and make sure you feel confident before you commit to anything.
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Frequently Asked Questions
What's the difference between an as-built drawing and a permit?
An as-built drawing is the technical document showing your property's current condition. An as-built permit is the county's official approval based on that drawing. You need the drawing to apply for the permit.
How long does an as-built permit take on the Big Island?
Timelines vary significantly based on Building Division workload and how much correction work is needed. Complex cases involving structural or wastewater upgrades take longer than simple documentation-only reviews.
Can I sell my Big Island home with unpermitted work?
Yes, but Hawaii's Seller's Real Property Disclosure Form legally requires you to disclose known permit violations, and many lenders won't finance a purchase with unresolved violations — so it can complicate or delay closing.
Will legalizing old unpermitted work require expensive upgrades?
Sometimes. County reviewers can require current-code upgrades like hurricane straps, updated wastewater systems, or flood-zone compliance before approving older work, even if it's been standing for years.
Do I need a licensed professional to create as-built drawings?
For most residential permitting purposes, yes — Hawaii County generally expects drawings from a licensed surveyor, drafter, or architect, and certain systems (like individual wastewater systems) legally require a licensed engineer's design.
What happens if I ignore an unpermitted structure?
It doesn't resolve itself. Unaddressed violations can result in county enforcement action, complications at resale, and reduced property value, since informed buyers and lenders both view unpermitted square footage as risk.
Where do I submit permit applications on Hawaii Island?
Applications go through the Hawaii County Department of Public Works Building Division, with offices serving East Hawaii (Hilo) and West Hawaii (Kona).
Ready to Legalize Your Big Island Property?
Unpermitted work doesn't have to become a crisis, but it does need a plan. Start by finding out exactly what's on file for your property, then bring in a licensed professional to prepare accurate as-built drawings before you talk to the county. If you're planning a renovation, selling, or just found out about a permit gap, reach out to a local permitting professional to map out your next step before it becomes a bigger (and more expensive) problem.
References
Hawaii County Department of Public Works – Building Division, Permit Information
Hawaii County Residential Building Permit Guidelines & Checklist
Hawaii County DPW – Protection of Openings Plan Requirements (Wind Speed Code, R301.2.1.2)
Hawaii State Legislature – SB368, Cesspool Conversion Law (HRS §342D-72)
Hawaii County Department of Environmental Management – Integrated Wastewater Management Plan
U.S. Department of Energy – Official Definition, "As-Built Drawings"
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