Exterior wall insulation: polystyrene and volcanic pozzolan
Insulation isn’t a single property. A block combines two different sources: the material of the block itself and the insulation slab inside it.
Source one: volcanic pozzolan
Volcanic block is made from a mix containing volcanic pozzolan, with a thermal conductivity of 0.125 W/m·K. The air voids inside the block add to the insulation while reducing weight, bringing its weight close to that of an equivalent red brick block.
Source two: the polystyrene slab
In the insulated type, the polystyrene slab is placed inside the block during production — wet or dry — so it is integral to and symmetrical with the block body rather than glued on. The result is excellent, cohesive thermal insulation that doesn’t separate over time.
Why is it required for exterior walls?
This technique is widely used in Europe and Saudi Arabia, and municipalities and the electricity company require it for exterior walls as part of energy-efficiency requirements.
An important design note
The values above describe the block itself. The wall’s thermal performance is calculated for the complete wall — block, plaster, finish and joints — by the design engineer. If your project specifies a particular U-value or R-value for the wall, state it in your quote request so a dedicated report can be issued for it.
An often-overlooked construction advantage
The rough surface of volcanic block lets plaster bond quickly and firmly, so it doesn’t need a heavy spatter coat — saving both material and labor.
