A heavy and rigid inertia block is often used as the base for equipment in order to reduce motion, lower the centre of gravity, minimize the effect of unequal weight distribution of the support equipment, and stabilize the entire vibration isolation system. Generally an inertia block should be at least 15cm thick and very stiff and rigid to avoid significant flexure in any direction. Table 16 shows a recommended weight of inertia block for various rating of equipment.
However, when the mass of the supported equipment is enormous, there may be no need for additional mass in the form of inertia blocks; a rigid frame to support (e.g. Reinforced Concrete Beam) the entire assembly may be sufficient.