HVAC Mold Cleaning in Renton, WA

The thermostat clicked, the furnace in the garage lit, and within ten minutes the living room smelled like the inside of a damp tent. It faded by lunch and came back the next morning. The house is a 1994 two-story on Benson Hill with the furnace in the garage and the ducts running under the floor through the crawl space. This site connects you by phone with an independent local provider who does HVAC mold cleaning in Renton and across King County.

Following the duct run, not just opening the furnace door

The provider starts at the furnace: the blower compartment, the filter rack, and the evaporator coil if the house has a heat pump or air conditioning. Then they follow the supply trunk into the crawl space, because in a Renton house that is where the ducts spend the winter. Flex duct lying on damp soil, a trunk line with a disconnected joint pulling crawl-space air, or insulation on the duct that has been wet since the last flood all get photographed and metered.

The return side gets the same look. A return that draws from a hallway over a damp crawl space, with gaps around the boot, is pulling that air into the system every time the blower runs. The crew scopes what they can with a camera and marks which sections are cleanable and which need to be replaced.

Swap the filter, set the fan to auto, and open the hatch

Change the filter now and look at the old one; a filter that is gray and damp on the intake side tells the crew something. Set the thermostat fan to auto so the blower only runs when the furnace fires, instead of circulating crawl-space air all day. Open the crawl-space hatch and look for standing water, slumped insulation, or a duct lying in a puddle, and photograph what you see.

Do not spray anything into the registers or the return. Fragrance covers the smell for an afternoon and leaves the wet material where it was. If the furnace cabinet itself shows growth, leave the door closed until the crew arrives.

Cabinet and coil cleaned, bad duct runs replaced, the crawl space dealt with

The blower assembly and cabinet are HEPA vacuumed and wiped, and the coil is cleaned with a product made for it. Rigid metal duct that reads dry is cleaned in place with the registers sealed and the system under negative pressure. Flex duct that has sat in water, or duct insulation that is wet, is cut out and replaced rather than cleaned, because wet fiberglass does not come clean. Boots and joints are resealed so the system stops pulling from the crawl space.

None of that holds if the crawl space stays wet. Standing water and soaked insulation under the ducts are whole-home mold remediation when the growth has reached the joists, or part of this job when it has not. A musty smell that persists after the system is clean is mold odor removal. Reinsulating the ducts and closing the floor is mold damage repair.

Garage furnaces, crawl-space ducts, and nine months of heating season

Renton homes built from the 1960s through the 2000s put the furnace in the garage or a hall closet and run the ducts under the floor, and in this climate the furnace runs from late September into May. Every one of those months the ducts sit in a crawl space whose air is close to saturated and whose soil may be wet from a downspout, a high water table in the valley, or river water that got in during a storm. The ducts are the one part of the house that touches the crawl space and every room above it.

Washington does not license mold work; the provider represents its own training. Replacing ductwork is mechanical work that needs a contractor registration with the state Department of Labor and Industries and usually a mechanical permit through the City of Renton, or King County outside the city line. Homeowners policies rarely pay for cleaning that traces back to humidity, so the crew's photos and notes are mostly for your own records.

Calling about a furnace that smells like the crawl space

Have the address, where the furnace sits, and whether the ducts run under the floor or through the attic. Say when the smell is worst, whether the crawl space has water in it now, and whether the house has had a flood or a plumbing leak in the last few years. Call (425) 584-6572.