Glavel as a sub slab aggregate layer derives much of its load bearing strength and thermal insulation from compaction. A foam glass install’s compaction is done at a 1.3 : 1 ratio, which locks the frictional pieces to one another, creating a smooth layer upon which slab can be poured. 

The compacting of Glavel takes place with a light vibratory plate. A support layer for the foundation slab is achieved with the devices listed below. The type of vibrating plate to be used depends on the properties of the sub grade and the Glavel layer thickness. It is highly recommended that a test area is used at a suitable location to check the compaction behavior of the layer sequence.

For hard surfaces and low gravel layer thicknesses, lightweight devices tend to be suitable. For softer surfaces and large insulation Glavel layer thicknesses, heavier devices are required.

The compression ratio of the insulation ballast layer is 1.3 : 1. The compaction is to be stopped when the target value is reached. Any additional compaction will serve only to increase material consumption without increasing insulative value or compressive strength. 

A compacted Glavel layer of Glavel can be flattened to + – 1 inch over a 6 square yard area.