Dry Rot

What is Dry Rot? 

Dry rot is the decay of building timbers used in the construction of wooden structures.  Most of the homes in this area are constructed using wood. Even though homes may have brick, stucco, or stone exterior walls, the basic structure frame is made of wood. Trim on most houses is also made of wood.

Dry rot is caused by a fungus which changes the composition of the wood, making it brittle. Over time, the decay causes instability and eventually the collapse of the structure. The dry rot fungus requires an elevated moisture content of 28-30% in order to start growing on the wood. The name "dry rot" can be confusing as it implies decay occurring without the presence of moisture. Dry refers to the dry wood used in construction as opposed to wet wood - the wood in living or newly felled trees.

How to Fix Dry Rot

The first step in handling dry rot is to correct the condition that led to the initial growth of fungus by eliminating the cause of dampness in the area and increasing ventilation to the site. Letting the affected wood dry out will kill dry rot since it is a fungus and requires water in order to live and grow.

Next, wood that has been weakened by fungus growth should be repaired or replaced. 

San Luis Obispo's climate is a nursery for dry rot. Many times dry rot can be found in the structural members of buildings and decks. If handled early, repairs can be made quickly and without requiring partial or complete demolition and re-construction.  

Signs of Dry Rot


Water spots on walls, ceilings, or carpets; discoloration of vinyl floors, carpets, or the shelf under the sink; warping of flooring (usually in kitchen or bathroom); wrinkling, sagging, or crumbling of sheetrock on the walls or ceilings.


Warping or swelling of siding; bubbling or lifting of paint; ends of fascia boards are soft or crumbling; any wood with areas of softness where a screwdriver can be pushed in easily. 

CAL COAST CONSTRUCTION has years of experience handling cases of dry rot in the most cost-effective and efficient manner possible.