Why did Mohenjo-daro use so many baked bricks?

At the ancient site of Mohenjo-daro, the extensive use of baked (or burned) brick was a strategic choice driven by environmental and functional needs. Unlike other sites of the Indus civilization, such as Kalibangan, where baked brick was reserved primarily for specialized infrastructure like drains and wells, Mohenjo-daro utilized it more broadly, potentially due to the greater availability of timber required for the fuel-intensive kiln-firing process.1

Baked bricks were essential for structures exposed to moisture, high wear, or structural stress. They were used to ensure the durability of bathrooms, wells, and drainage systems, which were critical for the city's advanced sanitation. Furthermore, the city’s walls were often plastered with mud to protect them from salts contained within the bricks, which could react destructively to fluctuations in heat and humidity. While mud brick remained common for mass work and fillings, the use of baked brick provided the necessary resilience for the city's monumental architecture, defensive fortifications, and infrastructure in a flood-prone alluvial plain.123