Timber pathology — due to the biological attack known as dry rot, what characteristic degradation is observed in affected wood components?

Introduction / Context:
Dry rot is a serious fungal decay affecting timber in buildings and structures. Recognizing its symptoms allows timely remediation and prevents structural failures. Unlike simple shrinkage or superficial cracking, dry rot degrades the cell wall polymers, leading to catastrophic loss of integrity.

Given Data / Assumptions:

• Dry rot fungi digest cellulose and hemicellulose, leaving a brittle, crumbly residue.
• Conditions: intermittent moisture, poor ventilation, and warmth.
• Timber species and preservative treatment influence susceptibility.

Concept / Approach:

The hallmark of dry rot (e.g., Serpula lacrymans) is that the attacked wood becomes brown, cubically cracked, and ultimately crumbles to a dry powder. This is distinct from simple cracking due to drying or minor shrinkage. While cracking and shrinkage accompany the process, the defining manifestation is the wood’s reduction to a friable, powdery mass that has lost structural capacity.

Step-by-Step Solution:

Verification / Alternative check:

Conservation manuals and building pathology texts describe dry rot’s advanced stage as wood becoming powdery and non-load-bearing, requiring replacement and source-moisture elimination.

Why Other Options Are Wrong:

Cracks — Present but not definitive; many non-biological causes also crack wood.
Shrinks — Common with drying but not diagnostic of dry rot alone.
None of these — Incorrect because the powdery disintegration is characteristic.

Common Pitfalls:

Confusing dry rot with wet rot; assuming surface cracking equals dry rot without checking internal friability and fungal growth.

Final Answer:

reduces to powder