Building stones — A good-quality stone should absorb less than what percentage of water by weight?

Introduction / Context:
Water absorption is a simple field indicator of stone quality. Lower absorption generally correlates with higher density, strength, and durability against freeze–thaw and chemical attack, which matters for masonry and facing works.

Given Data / Assumptions:

• “Good-quality” refers to stones used in structural or durable architectural applications.
• Standard lab water absorption test by weight.

Concept / Approach:
Engineering handbooks typically specify that quality building stones should have water absorption below approximately 5% by weight. Exceeding this suggests higher porosity and potential durability issues.

Step-by-Step Solution:
Assess thresholds: top-grade stones aim for water absorption under 5%.Relate porosity to durability: lower absorption → improved performance in service.Select the tightest standard value among the options: 5%.

Verification / Alternative check:
Common specifications for façade and load-bearing stones limit water absorption to ≤ 5%.

Why Other Options Are Wrong:
10–25%: represent increasingly porous stones; not considered “good quality” for demanding applications.

Common Pitfalls:
Confusing brick water absorption limits with stone; criteria differ by material.

Final Answer:
5%