Crawlspace Ductwork in Oregon Homes: What to Check Before Duct Cleaning

Why crawlspace ducts deserve a closer look in Oregon

The Oregon Department of Energy has noted that many homes built during the 1990s housing boom came with flexible ducts that are easily damaged, usually by rodents or water in the crawl space. The same post quotes a Salem energy contractor observing that most people don't want to even look into their crawl space — which is how damage goes unnoticed.

Code has since changed. The 2023 Oregon Residential Specialty Code requires new duct systems in new construction and additions to 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. Homes built before that code weren't held to the same rule.

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)

What to look for (from the crawlspace hatch, if you can do it safely)

You don't need to crawl the whole space to learn a lot. With a flashlight from the access opening, look for:

• Ducts lying on the ground, sagging, or disconnected at joints.
• Torn or chewed outer jackets or insulation on flexible ducts.
• Standing water, wet insulation, or signs of past flooding.
• Rodent droppings or nesting material near ducts or registers.

Sources: Oregon Department of Energy — Sealing Ductwork (Energy Info blog, Feb. 5, 2016); U.S. EPA — Should You Have the Air Ducts in Your Home Cleaned?

When repair has to come before cleaning

Cleaning a damaged duct doesn't fix it. A torn, disconnected, or crushed duct is a repair for an HVAC contractor. EPA is specific about wet materials: if insulated ducts get wet or moldy, the insulation can't be effectively cleaned and should be removed and replaced.

EPA also recommends that ducts in unconditioned spaces such as crawl spaces be properly sealed and insulated, and notes that sealing duct air leaks can help save energy on heating and cooling. That, too, is contractor work rather than part of a cleaning visit.

Source: U.S. EPA — Should You Have the Air Ducts in Your Home Cleaned?

When cleaning makes sense

Once the ducts are intact, EPA's criteria are a good guide. Consider cleaning if ducts have been infested with rodents or insects, are clogged with excessive dust and debris, or particles are being released from supply registers. EPA also lists substantial visible mold growth inside hard-surface ducts; mold assessment and removal are specialist work and aren't part of our cleaning. Either way, EPA says the underlying cause must be corrected before cleaning, or the problem will likely recur.

EPA notes that controlling moisture is the most effective way to prevent biological growth in air ducts, and that duct cleaning has never been shown to actually prevent health problems. If someone tells you there's mold in your ducts, EPA suggests asking them to show you, and notes that confirming mold may take an expert and laboratory analysis.

Source: U.S. EPA — Should You Have the Air Ducts in Your Home Cleaned?

Getting ready for a cleaning visit

If your ducts run under the floor, a clear path to the crawlspace opening helps, and any standing water should be dealt with first. Mention the crawlspace, your system type, and anything you spotted from the hatch when you request an estimate.