For a smooth installation and optimal performance, it's essential to have a flat and level with a maximum slope of 10 mm in one direction for proper drainage. Slopes greater than this, or in multiple directions, can cause issues or prevent installation. Our recommended base options include smooth flag paving, timber or composite decking, or a concrete foundation. Paving must have solid cement or concrete under foot positions, and decking must have solid timber joists. Please keep in mind that side screen alignment cannot be guaranteed on an uneven base. For detailed guidance on specific measurements, refer to our handy measuring guides. More here.