Understanding Wood Rot

Wood is a timeless and versatile material that has been used in construction for centuries and is the most common type of residential framing in Nova Scotia by a large margin. From framing to flooring, it brings warmth and beauty to our homes, and nothing beats the smell of wood, at least to this home inspector! However, lurking beneath its appealing surface lies a hidden threat that can compromise the integrity of any structure: rot. It's crucial to understand the damaging effects of rot on wood and the necessity of identifying and addressing it promptly. 

Wood rot is a natural process caused by fungi that break down the structural components of wood. These fungi thrive in environments with high moisture content and poor ventilation. They feed on the cellulose and lignin within wood, gradually weakening its structural integrity. If left unchecked, rot can spread throughout a building, leading to severe damage, compromised safety, and expensive repairs.

Types of Wood Rot
There are two primary types of wood rot:

1. Brown Rot: Brown rot is commonly known as dry rot (which is a misnomer if there ever was one) and tends to affect softwoods such as pine and spruce, which is used for the overwhelming majority of wood construction in North America. The affected wood becomes dry, cracked, and crumbly, often taking on a dark brown or reddish color. Brown rot typically progresses rapidly, leaving the wood weak and brittle.
2. White Rot: White rot attacks hardwoods such as oak, ash, and maple. As the name suggests, it appears as a whitish or yellowish discoloration on the wood's surface. Unlike brown rot, the affected wood retains its moisture and becomes spongy, stringy, and fibrous. White rot tends to spread slowly and can lead to significant structural damage over time.

Signs of Wood Rot
Detecting wood rot requires a keen eye during home inspections. Look out for the following signs:

1. Visible Discoloration: Dark brown, reddish, or whitish patches on wood surfaces can indicate rot.
2. Softness or Sponginess: Pressing on wood surfaces should reveal a solid and firm structure. If it feels soft, crumbly, or spongy, rot may be present.
3. Fungal Growth: The presence of mushrooms, mold, or mildew on or near wood surfaces suggests high moisture content and potential rot.
4. Musty Odor: A persistent musty smell in certain areas of a building is often an indication of hidden wood rot.
5. Cracks and Crevices: Check for cracks, splits, or crevices in the wood, as these provide entry points for moisture and fungi.

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Wood rot is a formidable adversary that can compromise the structural integrity and safety of a building. As a home inspector, being knowledgeable about the causes, signs, and impact of wood rot is essential for providing thorough assessments. In the example below, the deck railing was pressure treated (PT) but no treatment was added to the cut area. This lead to moisture infiltration, which is the most essential ingredient to wood rot. 

This is an example of "dry" rot, which is anything but.

Wood rot is a valuable function of nature, allowing dead wood to decompose and form nutrients for new trees to take root and complete the natural cycle. However, the interests of a homeowner is to slow down this process as much as possible by keeping moisture at bay.