Duct and Dryer Vent Cleaning for Oregon Homes, From the Crawlspace Up

Marine valleys and high desert

Oregon has two broad climates. NOAA's state climate summary notes that temperatures on the western side are generally mild thanks to the Pacific, while the Cascades block moisture, leaving the eastern part of the state much drier. Most areas get the bulk of their precipitation in winter.

The federal county climate map follows the same line. Multnomah, Washington, Lane, Marion, and Jackson counties are in a marine zone (IECC 4C), while Deschutes County and much of eastern Oregon are in a cold, dry zone (5B).

Temperatures are rising, too: NOAA reports that Oregon has warmed about 2.5°F since the beginning of the 20th century, and that the 2005–2009 and 2015–2020 periods had the highest number of extremely hot days (100°F or higher) in the historical record. If your household runs air conditioning more than it used to, that's more run time for the filter and ducts, so it's worth checking the filter more often.

Sources: NOAA State Climate Summaries 2022 — Oregon; PNNL for U.S. DOE Building America — Guide to Determining Climate Zones by County (IECC 2021 updates)

Ducts under the floor

The Oregon Department of Energy has noted that many Oregon homes built during the 1990s housing boom came with flexible ducts, which are easily damaged — usually by rodents or water in the crawl space.

Newer construction is moving the other way. Under the 2023 Oregon Residential Specialty Code, new duct systems in new homes and additions must be located fully within the building thermal envelope, with limited exceptions — for example, up to 10 feet of insulated ductwork outside the envelope, ducts deeply buried in attic or vented-crawlspace insulation, or ducts in an unvented crawlspace that meets specific requirements. Oregon's Building Codes Division also notes that when a furnace, air conditioner, or heat pump is replaced or added, existing ductwork doesn't have to be insulated to current code.

For a cleaning visit, the location of the ducts matters: it affects how they're reached and whether damage needs to be repaired first. EPA advises that ducts in unconditioned spaces such as crawl spaces be properly sealed and insulated, and that insulation that gets wet or moldy can't be effectively cleaned and should be removed and replaced.

Sources: Oregon Department of Energy — Sealing Ductwork (Energy Info blog, Feb. 5, 2016); Oregon Building Codes Division — Technical Bulletin: Duct systems, air handling equipment and appliances (2023 ORSC); U.S. EPA — Should You Have the Air Ducts in Your Home Cleaned?

Wildfire smoke season

NOAA's climate summary for Oregon projects that drier summers, higher temperatures, and earlier snowmelt will increase the frequency and severity of wildfires, and it cites the 2020 Labor Day fires among recent damaging events.

For smoke, the Oregon Health Authority recommends a MERV-13 or better filter on your heating, ventilation, and air conditioning system, and running air conditioning with the fresh-air intake closed and the filter clean. Duct cleaning isn't a substitute for filtration — EPA notes it has never been shown to actually prevent health problems.

Sources: NOAA State Climate Summaries 2022 — Oregon; Oregon Health Authority — Protect your health and property during wildfire season (May 8, 2025); Oregon Health Authority — Wildfires and Smoke: Get Prepared; U.S. EPA — Should You Have the Air Ducts in Your Home Cleaned?