What is changing in the Oregon crawl space code in 2026?

Less than the headline suggests. Of the crawl space provisions in the published committee matrices, most of Oregon's existing R408 amendments are recorded as retained — the Class I vapor retarder with 12-inch laps and 12 inches up the perimeter wall, the ventilation ratios, the vent placement rule, the vent covering rule, and the unvented crawl space requirements. The substantive approved change is an add-back permitting a continuously operated mechanical ventilation system at 1.0 cfm per 50 square feet of under-floor area in place of foundation vents. Separately, the energy chapter the board approved raises the under-floor insulation values in the prescriptive envelope table. The board approved both and the edition is in effect, but this site has not yet read the published text, so confirm either one with the building department before relying on it.

Do the 2026 changes affect my existing Portland home?

Not unless you are doing permitted work. A building code governs work that is done, not houses that already exist — no code edition requires you to alter a crawl space you are not otherwise working on. It matters when you pull a permit, and which edition applies to your project is decided by your local building department, not by this page. Until March 31, 2027 either edition may be used, and the rule says the code in effect when the plan review or permit application is filed controls that work, which is worth settling before signing a contract that spans the changeover.

Is the vapor barrier requirement changing in 2026?

On the published record, no. Oregon’s existing amendment — a Class I vapor retarder over the under-floor space, lapped not less than 12 inches at the joints and extended not less than 12 inches up the perimeter foundation walls — is recorded in the committee matrix as retained, and the board approved the committee’s recommendations. A vapor barrier scope written to that requirement is written to the same requirement under either edition. The one crawl space vapor retarder item marked for deletion is R408.8, a model code section the division states does not apply in Oregon at all.

Which edition applies to my project, the 2023 or the 2026?

Until March 31, 2027, whichever your plans are designed to: the adopting rule requires building departments to accept either. The code in effect when the plan review or permit application is filed controls the work under it, unless the applicant agrees to be governed by later changes. From April 1, 2027 the 2026 edition is the only one adopted. Ask the building department which edition your permit will be reviewed under, and ask the contractor to name the edition in the written scope.

Has this page checked the final 2026 code text?

Not yet. The edition is final in the sense that matters legally: it was adopted by rule and has been in effect since October 1, 2026. But on October 2, 2026 neither the division nor its publisher had posted the 2026 text, so the rows on this page are taken from the review matrices the board approved. The next check is October 15, 2026; each changed row will then be confirmed against the code itself or corrected. If you need certainty before then, ask your local building department.

Code Tracker

2026 Oregon Crawl Space Code Changes

Oregon adopted the next edition of its residential building code on September 30, 2026, and it took effect the following day. This page tracks what the published record shows for crawl spaces: which R408 provisions were kept as they are, which changes were approved, what the six-month phase-in means for a job being quoted now, and where each of those claims comes from. It is deliberately narrow — for what Oregon requires of a crawl space today, read the current requirements.

The 2026 edition is in effect. Its published text has not been checked here yet.

The rule adopting the 2026 Oregon Residential Specialty Code (ORSC) was filed on September 30, 2026 and took effect October 1, 2026. Until March 31, 2027, building departments must accept plans designed to either that edition or the 2023 Oregon Residential Specialty Code (ORSC). When this page was checked on October 2, 2026 the division’s own adoption page still called the date anticipated, and the 2026 code text had not been posted. So each changed row below is marked Approved, final text not yet read: it records what the board approved, which is not the same as quoting the adopted wording.

The short version

Oregon’s crawl space requirements are almost entirely the same under the new edition. The 2026 Oregon Residential Specialty Code (ORSC) took effect October 1, 2026, and the committee that reviewed it recorded the crawl space provisions a homeowner deals with as retained — the same requirements, carried forward. Until March 31, 2027 a project can be permitted under either edition.

What those requirements are, in plain terms. Oregon permits a crawl space to be built either way:

Vented. The ground is covered by a Class I vapor retarder, lapped at least 12 inches at the joints and run at least 12 inches up the perimeter walls, and the space has vent openings — 1 square foot of net opening per 150 square feet of floor in the counties where ORS 455.365 requires radon-mitigating construction, or 1 per 1,500 elsewhere.
Unvented, meaning sealed or encapsulated. The vapor retarder is sealed, laps 12 inches where joints are not taped, and runs at least 12 inches up the stem wall — and the space then gets one of three conditioning methods: continuous mechanical exhaust at 1 cfm per 50 square feet, conditioned supply air at the same rate, or dehumidification sized in accordance with the manufacturer’s specifications. In the radon counties, which include Multnomah, Clackamas and Washington, an unvented crawl space is not permitted in new construction without an approved mechanical ventilation system.

If you are reading this because a contractor said the code has just changed: for these provisions, on the published record, it has not. Two things were approved that do change something — an allowance for mechanical ventilation in place of foundation vents, and higher under-floor insulation values in the energy chapter. The rest of this page is the evidence for both statements, provision by provision, with the state’s own documents behind each. For what the rules mean for a job you are quoting today rather than for the code cycle, should crawl space vents be open or closed is the practical version.

Status panel

Edition adopted: 2026 Oregon Residential Specialty Code (ORSC)
Current status: Effective since October 1, 2026
Adopting rule filed: September 30, 2026 (BCD 14-2026, amending OAR 918-480-0005)
Effective date: October 1, 2026, the date the division had anticipated
Based on: 2024 International Residential Code, Chapters 1 through 24 and Chapter 44 with nine appendices, as further amended by the division
Phase-in: Six months, October 1, 2026 to March 31, 2027. Chapter 1 of the 2026 edition has no phase-in. For the rest, the 2023 edition stays adopted for those six months and building departments must accept plans designed to either. The code in effect when a plan review or permit application is filed controls that work, unless the applicant agrees to later changes.
Earlier edition: 2023 Oregon Residential Specialty Code (ORSC), effective October 1, 2023 and still accepted through March 31, 2027
Published 2026 code text: Not yet posted. When checked, the division’s adopted-codes page and its publisher’s Oregon listing both showed the 2023 edition as the residential code.
Last checked: October 2, 2026
Next check: October 15, 2026

Adopted and in effect. The Building Codes Division filed the rule adopting the 2026 edition on September 30, 2026, and it took effect October 1, 2026. Chapter 1 applies with no phase-in. For everything else there is a six-month phase-in to March 31, 2027, during which every building department in the state must accept plans designed to either the 2026 edition or the 2023 edition. What this site has not yet been able to do is read the published 2026 code text, so the changed crawl space rows below record what the board approved, not the final wording.

Verified on October 2, 2026 against the Oregon Secretary of State’s administrative rules database, which carries the adopted rule, and against the Building Codes Division’s adoption page, adopted-codes page, residential program page, rulemaking list and hearing notice. On that date the division’s own pages had not caught up: the adoption page still gave October 1, 2026 as an anticipated date, the adopted-codes page listed only the 2023 edition, and the rulemaking list still showed the adoption as in progress. The sources are linked in full at the foot of this page.

The five stages, and why the distinction matters

A building code provision passes through stages that sound similar and are not. The single most common error in writing about a new code is treating a recommendation as a requirement; the second is treating a summary of what was approved as the adopted text. Every row on this page is tagged with exactly one of these.

Current law: Required today. The provision is in the 2023 Oregon Residential Specialty Code, which stays adopted through the phase-in, and the 2026 code review recorded it as retained, meaning carried into the new edition unaltered.
Proposed: Recommended during code development and not adopted. It has no legal effect, it can be changed or dropped before an edition is published, and nothing may be built to it.
Approved, final text not yet read: Approved by the Residential and Manufactured Structures Board, in an edition that has since been adopted and is in effect. This site has not yet been able to read the published text of the section, so the row records what was approved, which is not the same as quoting the adopted wording. Confirm it with the building department before designing or pricing to it.
Approved, not yet effective: Adopted by rule with an effective date still in the future. Real, dated, and not yet the rule you build to.
Effective: Adopted, operative, and checked by this site against the published code text. Where a phase-in period applies, the superseded edition may still be used for a stated window.

The edition as a whole is at the last stage: effective since October 1, 2026. Its rows are not all there with it. The 6 retained provisions are current law under either edition. The 4 changed ones stay at “approved, final text not yet read” until this site has read them in the published code.

What the 2026 edition changes

4 crawl-space-relevant items in the published committee matrices are recorded as approved changes. The Residential and Manufactured Structures Board approved the committees’ recommendations on January 7 and February 18, 2026, and the edition was adopted effective October 1, 2026. The published text of these sections has not yet been read here, which is what the status column says.

Changes to crawl space provisions approved for the 2026 Oregon Residential Specialty Code, with the 2023 requirement, the approved change, its stage and the homeowner impact
Topic	2023 edition	2026 change	Status	Homeowner impact
Mechanical ventilation in place of foundation vents R408.2 (approved add-back)	Not present in the 2023 ORSC as a standalone allowance under R408.2. A crawl space without foundation vents is handled today under R408.3, which requires a continuous Class I vapor retarder plus one of three conditioning methods.	The committee asked the division to add back a provision stating that ventilation openings are not required in the foundation where a continuously operated mechanical ventilation system is installed, sized to exhaust a minimum of 1.0 cfm for each 50 square feet of under-floor area, with the ground surface covered by an approved ground cover material. Recorded outcome: Approve. 26orsc-matrix.pdf, page 9, R408.2 add-back paragraph, outcome column: Approve	Approved, final text not yet read	This is the one substantive crawl space change in the published crawl space entries. It puts a mechanically ventilated, ground-covered crawl space back on the vented side of the code rather than only reachable through the unvented-crawl-space section. The board approved it and the edition is now in effect, but this site has not read the final wording, so confirm the section with the building department before a design relies on it.
Vapor retarder in crawl spaces (model code section) R408.8	A model code section that Oregon does not apply. The under-floor vapor retarder requirements that govern here are in R408.2.1 and R408.3.	The division proposed deleting the section on the grounds that it does not apply in Oregon. Recorded outcome: Approve. 26orsc-matrix.pdf, page 9, R408.8, outcome column: Approve	Approved, final text not yet read	Housekeeping rather than a change in what is required. It removes a section a reader could otherwise cite at an Oregon crawl space by mistake. No scope of work changes because of it.
Floor insulation over a crawl space Chapter 11 prescriptive envelope table (numbered T. N1102.5 in the matrix, proposed as T. N1101.2)	The table lists under-floor insulation at R-25 where nominal joist depth is 10 inches or less, and R-30 where it is greater than 10 inches.	The division proposed raising those to R-30 and R-38 respectively, with the paired U-factors moving from U-0.039 to U-0.033 and from U-0.028 to U-0.027. Recorded outcome: Approve, flagged by the division as a cost increase. 26orsc-matrixch11.pdf, page 2, row 15, outcome column: Approve	Approved, final text not yet read	An insulation job permitted under the 2026 edition would be specified to the higher value, with more material in the same joist bays; one permitted under the 2023 edition during the phase-in would not. Ask which edition a quote assumes. The board approved the energy chapter as reflected in this matrix, but the matrix renumbers the table and this site has not read the published text, so confirm the figure with the building department before pricing to it.
Crawl space access hatch insulation N1104.2.9	The section addresses attic hatches, vertical doors and pull-down stairs to unconditioned spaces.	The division proposed adopting provisions requiring access hatches from conditioned space to unconditioned spaces — attics and crawl spaces are both named — to be insulated to the same R-value the envelope table requires for the ceiling they are installed in, and to be weather-stripped. Recorded outcome: Approve. 26orsc-matrixch11.pdf, page 3, row 26, outcome column: Approve	Approved, final text not yet read	A small detail with an outsized effect on a cold floor: an uninsulated interior crawl space hatch is a hole in the thermal envelope. Approved by the board with the rest of the energy chapter, and a reasonable thing to ask for in a scope of work under either edition.

What is staying the same

This is the more useful half of the page and the half a headline would drop. For 6 of the crawl space provisions a Portland homeowner actually deals with, the committee recorded Oregon's existing amendment as retained — meaning the requirement carries into the 2026 edition unaltered. A vapor barrier or encapsulation scope written to these is the same scope under either edition.

Oregon crawl space code provisions recorded as retained in the 2026 code review, with the requirement and what it means for a homeowner
Topic	Requirement, unchanged	2026 outcome	Status	Homeowner impact
Vapor retarder coverage and laps, vented crawl space R408.2.1	The ground of an under-floor space must be covered by a Class I vapor retarder, lapped not less than 12 inches at the joints and extended not less than 12 inches up the perimeter foundation walls.	No change. The committee recorded the existing Oregon amendment as retained. 26orsc-matrix.pdf, page 9, R408.2, outcome column: Retain	Current law	A vapor barrier scope written to today’s requirement — full soil coverage, 12-inch laps, 12 inches up the stem wall — is not made obsolete by the 2026 edition on anything published so far. This is the requirement to hold a bid against under either edition.
Ventilation ratio, vented crawl space R408.2.2	Minimum net area of ventilation openings is 1 square foot per 150 square feet of under-floor area where radon-mitigating construction is required under ORS 455.365, and 1 square foot per 1,500 square feet where it is not.	No change. The committee recorded the existing Oregon amendment as retained. 26orsc-matrix.pdf, page 9, R408.2, outcome column: Retain	Current law	The ten-to-one difference between the two ratios turns on whether the house is in a county where radon-mitigating construction is required — which includes Multnomah, Clackamas and Washington. That stays as it is.
Vent opening placement R408.2.3	One ventilation opening is required within 3 feet of each exterior corner, with the existing exceptions.	No change. The committee recorded the existing Oregon amendment as retained. 26orsc-matrix.pdf, page 9, R408.2, outcome column: Retain	Current law	Corner placement is what stops a crawl space having dead zones that never see airflow. Unchanged, and still worth checking on a house where vents have been blocked by landscaping or an addition.
Vent opening coverings and louvers R408.2.4	Ventilation openings must be covered by one of the permitted materials, with openings no larger than 1/4 inch in least dimension. Louvers are prohibited where radon-mitigating construction is required under ORS 455.365, aligning with the radon appendix.	No change. The committee recorded the existing Oregon amendment as retained. 26orsc-matrix.pdf, page 9, R408.2, outcome column: Retain	Current law	The 1/4-inch limit is the figure that decides whether a code-compliant vent screen excludes mice as well as rats. It is not moving.
Unvented (sealed) crawl spaces R408.3	The vapor retarder must overlap 12 inches where joints are not sealed or taped, and its edges must extend not less than 12 inches up the stem wall. Unvented crawl spaces are not allowed where radon-mitigating construction is required under ORS 455.365, unless an approved mechanical ventilation system is provided in accordance with the exception in Section AF103.5, and the rest of this section is satisfied.	No change. The committee recorded the existing Oregon amendment as retained. 26orsc-matrix.pdf, page 9, R408.3, outcome column: Retain	Current law	The requirements that decide whether an encapsulation bid is complete — the liner detail, and the three conditioning methods — are unchanged on anything published so far. The radon-county restriction on unvented crawl spaces is also retained, which matters across most of the Portland metro.
Radon control methods appendix Appendix BE (formerly Appendix AF)	Oregon adopts and modifies the model radon control methods appendix. Radon-mitigating construction is required in the counties named in ORS 455.365, which include Multnomah, Clackamas and Washington.	No change to the adoption status. The committee recorded the existing Oregon amendment as retained; the appendix is relettered BE in the 2024 IRC arrangement. 26orsc-matrix.pdf, page 15, Appendix BE (AF) Radon Control Methods, outcome column: Retain	Current law	The radon dimension of sealing a Portland-area crawl space is not being relaxed. Test before and after sealing regardless of edition.

“Retain” is the outcome word the division's own matrix uses. It means the existing Oregon amendment stays; it does not mean the topic was overlooked.

Across the river: what Washington requires instead

Four of the metro areas covered by this site are in Clark County, Washington — Vancouver, Camas, Washougal and Battle Ground — and none of the above applies to them. Washington runs its own residential code, and on crawl spaces it is not a near-copy of Oregon's. A contractor quoting from Oregon habit will specify the wrong details north of the Columbia. The governing section is WAC 51-51-0408, amended by WSR 23-23-104 and effective 16 March 2024.

Crawl space requirements compared, Oregon Residential Specialty Code R408 against Washington Administrative Code 51-51-0408
Requirement	Oregon — ORSC R408	Washington — WAC 51-51-0408
Ventilation ratio	1 sq ft of net opening per 150 sq ft of under-floor area in the ORS 455.365 radon counties; 1 per 1,500 elsewhere with ground cover	1 sq ft per 300 sq ft, reducible to 1 per 1,500 where a Class I vapor retarder covers the earth
Ground cover	Class I vapor retarder, joints lapped not less than 12 inches	6-mil black polyethylene, overlapped at least 6 inches at the joints and run to the foundation wall
How far up the stem wall	Not less than 12 inches, attached and sealed	Not less than 6 inches, for the sealed option
Unvented crawl space	Permitted under R408.3 with one of three conditioning methods, but not in new construction in the radon counties absent an approved mechanical ventilation system	Permitted two ways: a sealed Class I vapor retarder 6 inches up the stem walls together with a radon system, or continuously operated mechanical exhaust at 1 cfm per 50 sq ft
Radon trigger	Radon-mitigating construction required in the counties named in ORS 455.365, which include Multnomah, Clackamas and Washington	Dropping ventilation below 1/300, or fitting operable louvers, requires a radon vent system complying with Appendix AF. Clark County is in EPA’s Zone 1, its highest category

The two differences that most often show up in a bid are the stem-wall height — 12 inches in Oregon, 6 in Washington — and the fact that Washington permits an unvented crawl space where Oregon bars one in new construction in the radon counties. If you are in Clark County and a quote specifies a 12-inch stem-wall termination and an Oregon CCB licence, both are signals worth asking about: Washington work requires an active Washington L&I registration, and CCB licences do not transfer across the river.

This page tracks the Oregon code cycle. The Washington column above is that state’s current requirement, and Washington's own code development runs on its own schedule, which this page does not follow.

Adoption timeline

The division’s planned schedule, set against what its documents and the state’s rule record show happened. A milestone is marked confirmed only where a published document records it — a date being in the past is not by itself evidence that the step took place.

July 22 – September 7, 2025 Confirmed

Public code amendment proposal period.

Proposals submitted in this window appear in the committee matrices under the PP prefix.
August 5, 2025 Confirmed

Residential and Manufactured Structures Board selects the two code review committees — one for Chapter 11 energy provisions, one for structural, fire and life safety, and mechanical provisions.
September – November 2025 Confirmed

Code review committee meetings.

The published outcome matrices are the product of these meetings and are the source for everything in the comparison below.
January 7 and February 18, 2026 Confirmed

Residential and Manufactured Structures Board approves the committees’ recommendations and sends the code to public hearing.

Planned for January 2026. The division’s hearing notice records both dates; its adoption page lists the structural, fire and life safety, and mechanical matrix with the January meeting and the energy matrix with the February one. Until October 2, 2026 this page recorded the board stage as unconfirmed.
February 2026 (planned) Not confirmed

Construction Industry Energy Board reviews the energy provision recommendations.

No document this site has opened records this review.
March 2026 (planned) Not confirmed

Mechanical Board reviews the mechanical provision recommendations.

No document this site has opened records this review.
August 18, 2026 Confirmed

Public rulemaking hearing on the rules adopting the 2026 ORSC. Written comment closed August 21, 2026.

Planned for July to August 2026. The notice of proposed rulemaking was filed on July 27, 2026. This page said on August 28 that no notice of the hearing was listed; that was wrong, and the hearing had already been held. See the corrections ledger.
September 30, 2026 Confirmed

The division files the rule adopting the 2026 ORSC (BCD 14-2026, amending OAR 918-480-0005 and 918-480-0010).
October 1, 2026 Confirmed

The 2026 ORSC takes effect. Chapter 1 applies with no phase-in; for the rest, a six-month phase-in begins during which building departments must accept plans designed to either the 2023 or the 2026 edition.

The date the division anticipated. The plan also said the 2026 code would be posted on the division’s website; it had not been when this page was checked.
March 31, 2027 Set by rule

Last day of the phase-in. From April 1, 2027 the 2026 edition is the only residential edition adopted.

What the published record does not cover

Silence in a code matrix is not the same as no change, and it is certainly not permission to guess. These crawl space topics are absent from the published 2026 material, so this page makes no claim about them either way:

Vapor retarder thickness in mils. The code specifies a Class I vapor retarder by permeance, not by mil rating, and nothing in the 2026 matrices changes that.
Crawl space drainage, sump pumps and groundwater. R408 is a moisture and ventilation section, not a water management one, and the matrices contain no crawl space drainage entry.
Retrofit and alteration triggers — when work on an existing Portland crawl space obliges you to bring the whole space up to current code. That is applied locally by the building department, and no matrix entry settles it.
Mold remediation. Oregon has no residential mold code provision, and the 2026 process does not introduce one.

What to actually do about it

If you are getting work done now, either edition can apply until March 31, 2027. Ask the building department which one your permit will be reviewed under, and ask the contractor to name the edition in the written scope. For the crawl space provisions most jobs turn on, the two are recorded as the same: hold a bid against the current R408 requirements.
If your permit will be applied for after March 31, 2027, it will be under the 2026 edition, which is then the only one adopted. The rule ties the edition to the date the plan review or permit application is filed, not to the date the work is done.
If you are being told a rule has changed, ask which section and which document. Every claim on this page names both, and the matrices are public — a claim that cannot name a section is not a claim about the code.
If insulation is part of the scope, note that the higher under-floor R-values were approved for the 2026 edition’s energy chapter and flagged by the division as a cost increase. During the phase-in a job can be permitted under either edition, so ask which one the quote assumes, and have the figure confirmed before pricing to it.

How this page is maintained

Last checked: October 2, 2026. That means the status sources below were opened on that date and said what this page reports. Each source carries its own date, and one that was not re-read keeps its older one.
Next scheduled check: October 15, 2026. It was set to fall shortly after the anticipated effective date so that a slipped date would be caught. The date did not slip; the check is now for the published 2026 code text, so the changed rows can be confirmed against the code itself or corrected.
Where the status lives: in one configuration file, not in prose across several pages. When the status changes, every page that states the edition in force changes with it in the same build.
What this page got wrong before October 2, 2026. It reported that no hearing notice had been listed and that the board stage was unconfirmed, when the hearing had been held on August 18 and the notice recorded the board’s approvals; and it went on describing the edition as proposed for two days after it took effect. The cause was a check that could not see a list the division’s page draws by script, and that looked at the division’s pages rather than at the state’s rule record. Both are entered in the corrections ledger, and the rule record is now checked first.
Found an error, or is a date now wrong? Tell us — name the section and the document. Corrections to a regulatory claim are made ahead of the next scheduled check, not at it, and they are recorded permanently in the public corrections ledger with the wording as it stood. Regulatory statements are the category this site has had to correct most often, which is the honest reason that ledger is linked from here.
This site is not a contractor and not a code authority. Portland Crawlspace Pros is a contractor-matching and marketing service; independent licensed contractors perform all work. Nothing here is a code interpretation, and your building department's reading of the code governs your project.

Sources

Every regulatory claim on this page traces to one of these documents, and each row names the page and outcome column it was read from so you can check it directly. The adoption and the phase-in are in the administrative rule. The two review matrices record what the committees recommended and the board approved; they are the best published record of what changed, and they are not the adopted code text, which this site has not yet been able to read.

Oregon Secretary of State, Oregon Administrative Rules Database, OAR 918-480-0005, Adopted Oregon Residential Specialty Code (BCD 14-2026, amend filed 09/30/2026, effective 10/01/2026) Checked October 2, 2026

That the 2026 Oregon Residential Specialty Code is adopted and took effect October 1, 2026: “Effective October 1, 2026, the 2026 Oregon Residential Specialty Code consists of” the 2024 International Residential Code, Chapters 1 through 24 and Chapter 44 and nine appendices including Appendix BE, “as further amended by the Division”. The phase-in: Chapter 1 is effective October 1, 2026 with no phase-in period; the 2023 ORSC, with the exception of Chapter 1, is adopted for six months beginning October 1, 2026 and ending March 31, 2027; and during that period all building departments in the state are required to accept plans designed to either edition. Also that the code requirements in effect when a plan review or permit application is filed control the construction under that application unless the applicant agrees to be controlled by later changes.

Note: The rule adopts the code by reference; it does not reproduce the text of R408 or any other section. What the 2026 edition says about crawl spaces has to be read in the published code, which this site had not been able to do on the date above.
Oregon Building Codes Division, Notice of rulemaking hearing: 2026 Oregon Residential Specialty Code adoption (20260818-26orscadoption-ph.pdf, 7 pages; notice of proposed rulemaking filed 07/27/2026) Checked October 2, 2026

That the rules adopting the 2026 ORSC went to a public rulemaking hearing on August 18, 2026, with written comment open to August 21, 2026, on a notice filed with the Secretary of State on July 27, 2026. Also the division’s own account of the board stage: on January 7 and February 18, 2026 the Residential and Manufactured Structures Board “approved the committee’s recommendations for the 2026 ORSC” and recommended that the code be sent to public hearing.

Note: A notice of proposed rules. It gives the effective date as anticipated; the adopted rule, OAR 918-480-0005, is what fixes it.
Oregon Building Codes Division, Oregon Residential Specialty Code Adoption Checked October 2, 2026

The division’s page for the 2026 ORSC adoption process: the base documents (the 2024 IRC, existing Oregon amendments in the 2023 ORSC, and public code amendment proposals), the two review matrices, the board meeting each matrix went to (the structural, fire and life safety, and mechanical matrix on January 7, 2026; the energy matrix on February 18, 2026), and the notice of rulemaking hearing.

Note: This page describes the process. When opened on the date above it still gave October 1, 2026 as an anticipated adoption date and had not been updated to record the adoption, which is in OAR 918-480-0005.
Oregon Building Codes Division, 2026 Oregon Residential Specialty Code — Code Adoption Notice, anticipated timeline of adoption (26orsc-timeline.pdf) Checked October 2, 2026

The division’s planned schedule for the 2026 ORSC, which the tracker’s timeline sets against what happened: the code amendment proposal window (July 22 – Sept. 7, 2025), the code review committee meetings (September–November 2025), the Residential and Manufactured Structures Board recommendation (January 2026), the energy and mechanical board reviews (February and March 2026), the public rulemaking hearing (July–August 2026), and an anticipated effective date of October 1, 2026 with an anticipated six-month phase-in.

Note: Titled an anticipated timeline. It is the plan, not the record: the dates that actually occurred are taken from the hearing notice and from the adopted rule, OAR 918-480-0005.
Oregon Building Codes Division, Adopted codes online Checked October 2, 2026

The division’s list of adopted code editions, with the official codebook links and the effective and mandatory dates of the 2023 ORSC.

Note: When opened on the date above this page listed only the 2023 ORSC for residential work. It had not yet been updated for the 2026 edition, whose adoption is recorded in OAR 918-480-0005.
Oregon Building Codes Division, Residential Structures Code Program Checked October 2, 2026

The 2023 ORSC effective dates as the division states them: administrative provisions effective and mandatory October 1, 2023; construction provisions effective October 1, 2023 with a six-month phase-in and mandatory April 1, 2024.

Note: When opened on the date above this page had not yet been updated for the 2026 edition.
Oregon Building Codes Division, 2023 Oregon Residential Specialty Code (ORSC) (2023 edition, based on the 2021 IRC) Checked October 7, 2026

Section R408 under-floor space requirements: ventilation openings and ratios for vented crawl spaces, Class I vapor retarder coverage and lap dimensions, and the three conditioning methods that permit an unvented crawl space: continuously operated mechanical exhaust or a conditioned air supply, each at 1 cfm per 50 square feet, or dehumidification sized in accordance with the manufacturer’s specifications (R408.3 item 2.3), which sets no pints-per-day figure. Also R408.2.4, which lists the six permitted ventilation-opening coverings and caps their least dimension at 1/4 inch — the figure that decides whether a code-compliant foundation vent screen excludes mice as well as rats.

Note: Effective October 1, 2023 (construction provisions mandatory April 1, 2024). The 2026 edition took effect October 1, 2026. Under OAR 918-480-0005 this 2023 edition, apart from Chapter 1, stays adopted through March 31, 2027, and building departments must accept plans designed to either edition until then, so confirm which one a permit is reviewed under before relying on a section number. What did and did not change for crawl spaces is tracked at /oregon/2026-crawl-space-code-changes/.
Oregon Building Codes Division, 2026 Oregon Residential Specialty Code — RMSB review code review matrix (Structural, Fire and Life Safety, Mechanical) (26orsc-matrix.pdf, 17 pages) Checked October 2, 2026

Every crawl space entry in the 2026 code tracker: the R408.2 under-floor vapor retarder, ventilation ratio, vent placement and vent covering amendments (page 9, outcome Retain); the committee’s approved add-back permitting a continuously operated mechanical ventilation system at 1.0 cfm per 50 square feet in place of foundation vents (page 9, outcome Approve); the R408.3 unvented crawl space amendment (page 9, outcome Retain); the deletion of R408.8 (page 9, outcome Approve); and Appendix BE (AF) Radon Control Methods (page 15, outcome Retain).

Note: A record of what the code review committee recommended, which the Residential and Manufactured Structures Board approved and sent to public hearing. It is not the adopted code text. The adopting rule takes the 2024 IRC “as further amended by the Division”, and this site has not yet been able to read the published 2026 ORSC to confirm that each outcome recorded here carried through unchanged.
Oregon Building Codes Division, 2026 Oregon Residential Specialty Code — Code review matrix, Energy Efficiency, Chapter 11 (26orsc-matrixch11.pdf, 5 pages) Checked October 2, 2026

The two Chapter 11 entries in the 2026 code tracker that touch a crawl space: the approved revision of the under-floor rows of the prescriptive envelope table (R-25 to R-30 at 10 inches or less of nominal joist depth, R-30 to R-38 above that), flagged by the division as a cost increase; and the approved provision requiring access hatches between conditioned space and unconditioned spaces such as crawl spaces to be insulated and weather-stripped.

Note: A record of what the Chapter 11 code review committee recommended, which the board approved on February 18, 2026 “as reflected in the matrix”. It is not the adopted code text, and this site has not yet been able to read the published 2026 ORSC. The matrix also renumbers the sections it lists, so a section number here may not match the 2023 ORSC or the published 2026 ORSC.
Oregon Building Codes Division, Residential and Manufactured Structures Board, Residential and Manufactured Structures Board meeting packet, July 1, 2026: draft minutes of the February 18, 2026 meeting (rmsb-20260701-agenda.pdf, 77 pages; draft minutes at packet pages 3 to 10) Checked October 2, 2026

The board’s February 18, 2026 motion on the energy chapter, carried on a roll call vote: to amend and approve the recommended Chapter 11 energy efficiency provisions of the 2026 ORSC “as reflected in the matrix” and forward them to the administrator for rulemaking and adoption. This is what ties the under-floor insulation and access hatch entries in the energy matrix to a board approval.

Note: Draft minutes, included in the packet for approval at the July 1, 2026 meeting. The one amendment the board made concerned N1102.4 and detached accessory structures, not crawl spaces.
Oregon Building Codes Division, Proposed rulemaking Checked October 2, 2026

Where the division lists rulemakings in progress, with their notices and hearings. It lists the 2026 ORSC adoption with its August 18, 2026 rulemaking hearing and the notice of that hearing.

Note: The list is drawn by script after the page loads, so it is missing from a plain download of the page. That is how this site came to report on August 28, 2026 that no notice was listed, which was wrong and is recorded in the corrections ledger. When opened in a browser on the date above the page still showed the ORSC adoption as a rulemaking in progress although the final rule had been filed on September 30, 2026: the division’s listings lag the Secretary of State’s record.
Washington State Legislature, WAC 51-51-0408 — Section R408, Under-floor space (Washington State Residential Code, amended by WSR 23-23-104) Checked August 30, 2026

What Washington actually requires under a house, which is NOT what Oregon requires: ventilation at 1 square foot per 300 square feet of under-floor area; 6-mil black polyethylene ground cover with joints overlapped 6 inches minimum, extending to the foundation wall; ventilation reducible to 1/1,500 where a Class I vapor retarder covers the earth, but a radon vent system complying with Appendix AF required where ventilation is below 1/300 or operable louvers are installed; and two unvented options — a sealed Class I vapor retarder extending 6 inches up the stem walls WITH a radon system, or continuous mechanical exhaust at 1 cfm per 50 square feet. R408.8 is not adopted in Washington.
U.S. Environmental Protection Agency, EPA Map of Radon Zones — Washington Checked August 30, 2026

That Clark County is in Zone 1, EPA’s highest of three radon categories, defined as a predicted average indoor screening level greater than 4 pCi/L. Zone 2 is 2 to 4 pCi/L and Zone 3 is below 2. This is the sourced radon fact behind the four Washington city pages, and it pairs with the Appendix AF radon vent system that WAC 51-51-0408 requires where crawl space ventilation is reduced.

Note: EPA states the map must not be used to decide whether an individual home needs testing, and that every home should be tested regardless of zone. A county-level prediction says nothing about one building.
Oregon Health Authority, Radon Program Checked September 1, 2026

Radon testing guidance and action levels for Oregon homes, referenced because sealing a crawl space changes how soil gas enters a house.

Sources last checked between August 30, 2026 and October 7, 2026; the date beside each one is when it was last opened. Where a figure comes from a document that is revised on a schedule, the edition or version is named above so you can confirm it against the current one yourself.

Questions, Answered

2026 Oregon Crawl Space Code: Common Questions

: Yes. The rule adopting it was filed on September 30, 2026 and it took effect October 1, 2026. Chapter 1, the administrative chapter, applies with no phase-in. For everything else there is a six-month phase-in to March 31, 2027, during which every building department in the state must accept plans designed to either the 2026 edition or the 2023 Oregon Residential Specialty Code (ORSC). As of October 2, 2026 the division had not updated its own adoption page and the published code text had not been posted, so the changed crawl space rows on this page record what the board approved rather than the final wording.
: Less than the headline suggests. Of the crawl space provisions in the published committee matrices, most of Oregon's existing R408 amendments are recorded as retained — the Class I vapor retarder with 12-inch laps and 12 inches up the perimeter wall, the ventilation ratios, the vent placement rule, the vent covering rule, and the unvented crawl space requirements. The substantive approved change is an add-back permitting a continuously operated mechanical ventilation system at 1.0 cfm per 50 square feet of under-floor area in place of foundation vents. Separately, the energy chapter the board approved raises the under-floor insulation values in the prescriptive envelope table. The board approved both and the edition is in effect, but this site has not yet read the published text, so confirm either one with the building department before relying on it.
: Not unless you are doing permitted work. A building code governs work that is done, not houses that already exist — no code edition requires you to alter a crawl space you are not otherwise working on. It matters when you pull a permit, and which edition applies to your project is decided by your local building department, not by this page. Until March 31, 2027 either edition may be used, and the rule says the code in effect when the plan review or permit application is filed controls that work, which is worth settling before signing a contract that spans the changeover.
: On the published record, no. Oregon’s existing amendment — a Class I vapor retarder over the under-floor space, lapped not less than 12 inches at the joints and extended not less than 12 inches up the perimeter foundation walls — is recorded in the committee matrix as retained, and the board approved the committee’s recommendations. A vapor barrier scope written to that requirement is written to the same requirement under either edition. The one crawl space vapor retarder item marked for deletion is R408.8, a model code section the division states does not apply in Oregon at all.
: Until March 31, 2027, whichever your plans are designed to: the adopting rule requires building departments to accept either. The code in effect when the plan review or permit application is filed controls the work under it, unless the applicant agrees to be governed by later changes. From April 1, 2027 the 2026 edition is the only one adopted. Ask the building department which edition your permit will be reviewed under, and ask the contractor to name the edition in the written scope.
: Not yet. The edition is final in the sense that matters legally: it was adopted by rule and has been in effect since October 1, 2026. But on October 2, 2026 neither the division nor its publisher had posted the 2026 text, so the rows on this page are taken from the review matrices the board approved. The next check is October 15, 2026; each changed row will then be confirmed against the code itself or corrected. If you need certainty before then, ask your local building department.

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