# Forum Home Renovation Concreting  Insulating under concrete slab

## CheeseAndWine

Hi all, I'm looking for some details about XPS insulated concrete slabs on ground...
1. Does the insulation generally completely cover the ground under the concrete or are there spaces left between the insulation boards?
2. Are there any issues with the concrete moving over time because of the insulation? 
3. Is there especially designed XPS for use under concrete slabs? 
Thanks much, 
Cheese

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