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Mechanical permit in SeaTac, Washington

Permit for heating, ventilation, air conditioning, refrigeration and fuel-gas equipment in SeaTac under the International Mechanical Code as adopted at SMC 13.160.010.

Verified 2026-09-16 · Source

When you need this permit

  • SMC 13.160.010: “The most current edition of the International Mechanical Code as amended by the Washington State Building Code Council and published in Chapter 51-52 WAC is hereby adopted by reference, as now or hereafter amended.” No edition year is printed.
  • SMC 13.160.020 “Copy on file” is “Repealed by Ord. 23-1016.” Chapter 13.160 therefore consists of a single operative section; the repeal is of the filing formality only and the adoption at 13.160.010 stands.
  • Mechanical work started without a permit draws the investigation fee at SMC 13.100.070(C), which names mechanical work expressly.
  • A mechanical permit is one of the permits “not necessary to complete a new building or a building addition”, so it expires one year from issuance and may be extended once by a maximum of six months — a shorter extension than a building permit's twelve.
  • CHECK WHO YOUR BUILDING OFFICIAL IS BEFORE YOU APPLY — ON PORT OF SEATTLE LAND IT MAY NOT BE THE CITY. SMC 13.100.010(C): “the City recognizes concurrent authority of the Port to administer, implement, and enforce the technical codes and standards adopted in this title and defers to the Port's exercise of such jurisdiction as to development projects on Port-owned property within the City which are for airport uses, as that term is defined in the February 17, 2018, interlocal agreement between the City and the Port.” The agreement is authorised by Resolution No. 17-021. The code does not reproduce the definition of “airport uses”, and that interlocal agreement was not read for this entry, so which projects fall inside the carve-out is NOT ASSERTED HERE.
  • THE APPLICATION HAS ITS OWN CLOCK, SEPARATE FROM THE PERMIT'S. SMC 13.100.060(H): an application for which no permit issues within eighteen months “shall expire by limitation”; separately it expires for inactivity if the applicant “fails to respond to the Department's written request for revisions, corrections, or additional information within ninety (90) days of the date of request”. The 90-day response period can be extended on an approved schedule, but the code is explicit that doing so “shall not extend the time limitation of the application” — the two clocks do not merge. Tolling is available for a cumulative maximum of 180 days: 90 days where a land use approval must come first, or 180 where issuance waits on a related construction permit, or on both. A separate one-time 30-day extension exists only “for the purpose of paying fees, submitting required paperwork, and posting financial sureties”.
  • SMC 13.100.100: appeals from the Building Official go to the Hearing Examiner, and “All references in the technical codes to the Board of Appeals shall be deemed to refer to the Hearing Examiner system of Chapter 1.20 SMC.” The section further limits the Examiner's authority over code interpretation; Chapter 1.20 SMC was not opened for this entry, so the procedure and any deadline are not asserted.

Required documents

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Fee schedule

Permit and plan review fee
SMC 13.100.070(A): “A permit or permit revision shall not be issued until all fees owed to the City of SeaTac have been paid. Show full citationSMC 13.100.070(A): “A permit or permit revision shall not be issued until all fees owed to the City of SeaTac have been paid. The permit and plan review fees, together with other fees, shall be as set forth in the most recently adopted City of SeaTac Fee Schedule.” NO DOLLAR AMOUNT APPEARS IN THE CODE, and the absence is bounded: The absence is bounded to SMC 13.100.060 and 13.100.070; the Fee Schedule itself is a separate document that was not opened. WHAT THE CODE DOES PUBLISH IS THE VALUATION METHOD, which is the input the fee is computed from — 13.100.070(B): “Project valuation shall be calculated based on the then-current August Building Valuation Data Square Foot Construction Costs Table published by the International Code Council or the actual value of the work for work not included in the published table”, and “The project valuation shall be set by the Building Official.” So an applicant can reconstruct the basis of the charge without being able to read the rate.
Set by City of SeaTac Fee Schedule
Investigation fee (work started without a permit)
SMC 13.100.070(C), work commencing before permit issuance: the investigation fee “shall be an amount equal to the permit fee with a minimum fee of one (1) hour at the standard hourly rate in the most… Show full citationSMC 13.100.070(C), work commencing before permit issuance: the investigation fee “shall be an amount equal to the permit fee with a minimum fee of one (1) hour at the standard hourly rate in the most recent City of SeaTac Fee Schedule”, and it “shall be in addition to the required plan review and permit fees” — so starting early roughly doubles the permit cost. It reaches buildings, electrical, gas, fuel tank, mechanical, plumbing and fire suppression work, work in the right-of-way, and land clearing including grubbing. The hourly rate is not published in the code.
Equal to the permit fee; 1 hour minimum
Refund of a paid permit fee
SMC 13.100.070(D) publishes the refund rule, which is unusual — most codes in this Washington set do not. Show full citationSMC 13.100.070(D) publishes the refund rule, which is unusual — most codes in this Washington set do not. A full refund where the fee “was erroneously paid or collected”; “A partial refund of eighty percent (80%) if a request for refund has been received within one hundred eighty (180) days of the expiration of an application or the issuance of a permit, and for which no plan review has started or inspections have been conducted.” Permits issued on incorrect, inaccurate or incomplete information, or in violation of any ordinance, are not eligible for a refund at all.
80% within 180 days if no review started

Review timeline

Plan review
Not published — contact the department

How long did your Mechanical permit permit actually take in SeaTac?

Anonymous — one question, no email. Answers are combined and only shown once at least 5 people have reported.

Inspection process

    Tips

    • MECHANICAL, ELECTRICAL AND PLUMBING PERMITS GET A SIX-MONTH EXTENSION, NOT THE TWELVE MONTHS A BUILDING PERMIT GETS. SMC 13.100.060(K)(2) sets that limit specifically, and only one extension is available.
    • The valuation you declare covers the trade equipment too — SMC 13.100.070(B) includes “electrical, gas, mechanical, plumbing equipment and other permanent systems” in the project value.

    Frequently asked questions

    SeaTac requires a mechanical permit for: SMC 13.160.010: “The most current edition of the International Mechanical Code as amended by the Washington State Building Code Council and published in Chapter 51-52 WAC is hereby adopted by reference, as now or hereafter amended.” No edition year is printed.; SMC 13.160.020 “Copy on file” is “Repealed by Ord. 23-1016.” Chapter 13.160 therefore consists of a single operative section; the repeal is of the filing formality only and the adoption at 13.160.010 stands.; Mechanical work started without a permit draws the investigation fee at SMC 13.100.070(C), which names mechanical work expressly.; A mechanical permit is one of the permits “not necessary to complete a new building or a building addition”, so it expires one year from issuance and may be extended once by a maximum of six months — a shorter extension than a building permit's twelve.; CHECK WHO YOUR BUILDING OFFICIAL IS BEFORE YOU APPLY — ON PORT OF SEATTLE LAND IT MAY NOT BE THE CITY. SMC 13.100.010(C): “the City recognizes concurrent authority of the Port to administer, implement, and enforce the technical codes and standards adopted in this title and defers to the Port's exercise of such jurisdiction as to development projects on Port-owned property within the City which are for airport uses, as that term is defined in the February 17, 2018, interlocal agreement between the City and the Port.” The agreement is authorised by Resolution No. 17-021. The code does not reproduce the definition of “airport uses”, and that interlocal agreement was not read for this entry, so which projects fall inside the carve-out is NOT ASSERTED HERE.; THE APPLICATION HAS ITS OWN CLOCK, SEPARATE FROM THE PERMIT'S. SMC 13.100.060(H): an application for which no permit issues within eighteen months “shall expire by limitation”; separately it expires for inactivity if the applicant “fails to respond to the Department's written request for revisions, corrections, or additional information within ninety (90) days of the date of request”. The 90-day response period can be extended on an approved schedule, but the code is explicit that doing so “shall not extend the time limitation of the application” — the two clocks do not merge. Tolling is available for a cumulative maximum of 180 days: 90 days where a land use approval must come first, or 180 where issuance waits on a related construction permit, or on both. A separate one-time 30-day extension exists only “for the purpose of paying fees, submitting required paperwork, and posting financial sureties”.; SMC 13.100.100: appeals from the Building Official go to the Hearing Examiner, and “All references in the technical codes to the Board of Appeals shall be deemed to refer to the Hearing Examiner system of Chapter 1.20 SMC.” The section further limits the Examiner's authority over code interpretation; Chapter 1.20 SMC was not opened for this entry, so the procedure and any deadline are not asserted.. If your project isn't listed, confirm with City of SeaTac at (206) 973-4800 before starting work.

    In SeaTac, the published Permit and plan review fee is: Set by City of SeaTac Fee Schedule. Additional published fees: Investigation fee (work started without a permit) — Equal to the permit fee; 1 hour minimum; Refund of a paid permit fee — 80% within 180 days if no review started. These are the jurisdiction's own published figures — see the fee schedule table and source citations on this page.

    SeaTac does not publish a plan-review timeline for this permit. Contact City of SeaTac at (206) 973-4800 for current turnaround.

    You'll need: Construction permit application; Applicant's estimated project value; Permit and approved plans kept on site. See the required-documents checklist on this page for details on each.

    Apply through City of SeaTac at 4800 S 188th St, SeaTac, WA 98188. Phone: (206) 973-4800. Official information: https://www.seatacwa.gov/.

    The chapter does not name one. SMC 13.160.010 adopts “the most current edition” of the IMC as amended by the State Building Code Council and published in Chapter 51-52 WAC, “as now or hereafter amended”. The operative edition is whichever the state chapter carries at the time; confirm it with the Building Official.

    Sources & verification

    Verified against official sources. Last reviewed 2026-09-16.

    Codes & ordinances

    Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the SeaTac building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.

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