Rotten Joists, Sills & Beams

Wood rot and termite damage occur when moisture is present long enough to support biological activity. Damp crawl spaces create ideal conditions for fungal decay and insect infestation. Rot slowly breaks down wood fibers, reducing strength and causing material to become soft or crumbly. Termites consume wood internally, often leaving outer surfaces intact while hollowing structural members from the inside.

Sill plates and subfloor areas are particularly vulnerable because they sit close to moisture sources and often receive condensation from plumbing and ductwork above. Bathrooms and kitchens frequently show early damage due to concentrated moisture exposure. Damage often progresses unnoticed because it occurs beneath the floor and behind finishes.

Surface treatments or chemical applications cannot restore strength to damaged wood. Once fibers are compromised, structural capacity is lost. Effective repair requires supporting via sistering or subfloor plating, or replacing girder beams to restore proper load transfer. Termite treatment alone does not repair damage, and rot will continue unless moisture conditions are corrected.

Long-term protection depends on eliminating the environmental conditions that allowed damage to occur. When crawl spaces are sealed and humidity controlled, wood remains dry and resistant to biological attack. Structural repairs then perform as intended for decades.

- BACK TO STRUCTURAL GUIDES