Yes, you can lay slabs on top of existing concrete. This is a common practice for many types of projects, such as driveways, sidewalks, and patios. If you are unsure whether or not your project is suitable for this type of installation, it is best to consult with a professional concrete contractor like Gresham Concrete Contractors. We can help you determine if your project is suitable for slab installation and if so, we can install the slabs for you.