Timber moisture content – freshly felled wood (based on dry weight) Based on its dry weight, a freshly felled tree may contain approximately what percentage of water?

Introduction / Context:
Moisture content is a central property in timber technology because it controls weight, strength, shrinkage, and susceptibility to decay. When engineers, carpenters, or building inspectors discuss moisture content, they typically define it on a dry-weight basis. Freshly felled timber can hold a surprisingly large mass of water relative to the oven-dry mass of the wood substance.

Given Data / Assumptions:

• We are asked for moisture content expressed on a dry-weight basis (the standard engineering definition).
• The material is freshly felled timber (green wood), not air-dried or kiln-dried.
• We seek an indicative value that is commonly cited in timber practice and textbooks.

Concept / Approach:

Moisture content on a dry basis is computed as: MC(%) = (mass of water / oven-dry mass) * 100. Because the denominator is the oven-dry mass, MC can exceed 100% when the mass of water is greater than the mass of the dry wood substance. In green wood, both free water (in cell lumens) and bound water (in cell walls) are present, often yielding very high moisture contents compared with seasoned timber.

Step-by-Step Solution:

Verification / Alternative check:

Species data show moisture contents for green wood commonly ranging from 60% to well over 100% on a dry basis. The fiber saturation point (roughly 25%–30% on a dry basis) marks the end of bound-water loss, but green wood contains free water too, pushing MC well beyond 30%—often near or above 100% in many cases. Hence 100% is a realistic benchmark choice for “freshly felled.”

Why Other Options Are Wrong:

25%: Close to the fiber saturation point; far too low for green wood.

50% or 75%: Possible for partially seasoned material, but commonly lower than many fresh cases; does not reflect the typical high MC of green timber.

Common Pitfalls:

Confusing dry-basis definition with wet-basis; assuming MC cannot exceed 100% (it can on a dry-basis definition). Neglecting the presence of free water in freshly felled timber.

Final Answer:

100%