The choice usually comes down to three things: the wall’s job, the climate it sits in, and what your masons are used to building with.

Thermal behaviour

Fired clay holds heat and releases it slowly, which is why old clay buildings stay comfortable through a Rajasthan summer. Hollow cement blocks trap air instead, and the cavity does similar work at a lower weight per square metre.

Speed on site

A 400 x 200 mm hollow block replaces roughly eight standard bricks. On a large boundary wall or a plain internal partition, that speed advantage is real money.

Where clay still wins

Anywhere the wall is going to be seen. Exposed clay brick ages into a better version of itself. Cement blocks need a finish coat, and that coat becomes a maintenance item.

A practical rule

Use hollow blocks where the wall will be plastered or hidden, and clay where the wall is part of the architecture. Mixing both across one project is normal and sensible.