Accessory Dwelling Units (ADUs) — those cozy backyard cottages and guest houses — have become increasingly popular across Washington State. According to the Washington State Department of Commerce, ADU permits increased by more than 35% in the last five years as homeowners look to add value and livable space to their properties. But these structures, often built close to trees, garden beds, and sprinklers, can be especially vulnerable to moisture. One common issue that flies under the radar is siding rot — a problem that can cause serious damage if ignored. Addressing this early with effective rot repair service can help protect your ADU investment.
Why ADUs Are Prone to Siding Rot
ADUs often face different exposure than the primary home. Located at the far end of a property, they may have less sun exposure and receive more moisture from surrounding landscaping, tree canopies, or nearby irrigation systems. Washington’s damp climate only amplifies this risk. Prolonged moisture can penetrate cracks or gaps in aging or improperly installed siding, leading to rot that can deteriorate structural components over time.
In fact, rot can go unnoticed for years because most ADUs don’t get inspected as thoroughly as primary homes. This can lead to hidden water damage that affects walls, insulation, and framing. Working with a professional who understands these unique conditions — like an experienced siding rot repair contractor — ensures that small problems don’t escalate into costly, disruptive repairs.
Warning Signs of Siding Rot in ADUs
Keep an eye out for the following signs of siding rot around your ADU:
- Soft, spongy spots on siding boards that give when pressed.
- Paint peeling or bubbling, which indicates trapped moisture beneath the surface.
- Mildew or algae growth on the outside walls.
- Warped or cracked siding boards that no longer sit flush.
- Musty odors indoors, which often signal rot that’s progressed into interior materials.
If you see these signs, it’s time to call in professionals who specialize in rot repair. Catching rot early is much more affordable than replacing entire walls or framing.
Prevention and Maintenance
Prevention is always better — especially for detached structures like ADUs that can go unchecked. Installing properly ventilated rain screens, ensuring seamless gutters and downspouts, and choosing rot-resistant siding materials (such as fiber cement or engineered wood) can greatly reduce the risk of siding rot. It’s also wise to schedule an annual exterior inspection and maintain proper landscaping drainage around the unit.
By treating your ADU like the primary home — inspecting its siding and exterior components regularly — you can stop rot before it spreads. A small investment in repair and prevention can preserve your unit’s value and extend its lifespan, saving you thousands in potential future repair costs.