San Francisco · Residential Dryer Exhaust Cleaning Inspection

Dryer Vent Cleaning & Inspection - San Francisco Garage

A single residential dryer in a San Francisco garage received a full exhaust cleaning and inspection, revealing heavy lint accumulation throughout the duct interior, a heavily clogged exterior vent cap, and several installation concerns worth monitoring for long-term safety.

Completed June 29, 2026

Two metal periscope-style exterior dryer vent caps side by side on a concrete foundation with wooden framing above: the left cap shows heavy lint on the housing and damper area, while the right cap appears clean with the louvered damper in proper open position

Before and after comparison of exterior vent caps showing lint removal and restored damper function

What We Found

Dryer Vent Specialists completed a residential dryer exhaust cleaning and inspection for a single dryer located in a garage in San Francisco (94116). The exhaust system was configured with the dryer fan mounted on an external wall, with an exposed duct run terminating through the foundation. Upon initial inspection, the exterior vent cap was removed and found to be severely obstructed: lint had built up heavily on the interior housing walls, the damper louvers were partially blocked and showed corrosion, and the cap opening was restricted enough to significantly impede airflow. A ground-level periscope-style vent termination was also noted, presenting concerns for water intrusion, pest entry, and debris blockage per IRC M1502.2, which requires the exhaust to convey moisture cleanly to the outdoors.

Inside the Duct and Dryer

Camera and rod inspection of the duct interior confirmed dense lint matting along both the upper and lower walls of the metal duct run, creating a substantially narrowed airflow channel. This level of accumulation is a recognized fire hazard and directly reduces dryer efficiency. Inside the dryer itself, the blower wheel, motor housing, mounting bracket, and drum surfaces all showed significant lint and dust buildup. Electrical wiring in the blower compartment was visible and coated with debris. The lint trap screen was also soiled and showed staining consistent with extended use without deep cleaning. Thorough cleaning was performed throughout: the duct interior, blower assembly, drum area, and exterior vent cap were all cleared of accumulated lint and debris.

Installation Observations

Several installation details were documented during the inspection. The duct penetration through the concrete foundation showed visible efflorescence, rust staining, and cracking around the opening, with a flexible white discharge hose connected via plastic clamps, indicating potential moisture intrusion at the foundation pass-through. A separate exterior vent cap on the wall showed corrosion and rust on its metal housing, and the electrical outlet box directly above it displayed exposed wiring and inadequate weatherproofing with gaps around the edges, lacking proper caulking or sealing where components meet the siding. While these electrical and weatherproofing items fall outside the dryer vent scope, they were flagged for the homeowner's awareness. Before-and-after comparison confirmed a clear contrast between the clogged and cleaned vent cap conditions, with the cleaned cap's louvered damper returning to proper operating position.

Outcome

Following the cleaning service, the dryer exhaust pathway was restored to unobstructed airflow from the dryer cabinet through the duct run and out the exterior termination cap. Homeowners in San Francisco with garage-based dryers, particularly those with ground-level or foundation-penetrating vent terminations, should schedule annual inspections given the increased exposure to moisture, pests, and debris at low-profile termination points. Dryer Vent Specialists recommends re-inspection within 12 months and evaluation of the termination cap height relative to grade to confirm ongoing code compliance with IRC M1502.2.