Timber MCQ with answer and solution

Concept

Fungi attack timber only when the moisture content is above about 20%, with air and a suitable temperature present.

Step-by-step solution

1. Fungi need food (wood), moisture, air and a suitable temperature to grow. 2. Below about 20% moisture content, fungi cannot grow in timber. 3. So fungal defects such as dry rot, wet rot, blue stain and heart rot occur when moisture content is above 20%. 4. Answer is (B) 20%.

Explanation

Fungi are small plants that live on wood. They need enough water to grow. Timber with moisture content above 20% is easily attacked, so timber should be seasoned below this value.

Why the other options are wrong

(A) 25%: fungi start growing before 25%, so this limit is too high. (C) 15%: at 15% timber is well seasoned and safe from fungi. (D) 10%: this is very dry timber, and fungi cannot grow.

Shortcut

Remember: fungi need more than 20% moisture.

Common mistake

Confusing this with the 10-12% moisture limit for seasoned timber used in furniture.