Hi. I'm after some help with building a deck. I have recent experience installing WPC deck boards on to a deck frame built by a carpenter. I now want to tackle a new deck build from start to finish. The deck will measure 4.0m x 2.7m. I have bought 2x6 C24 timber for the frame. The WPC boards will run along the 4m length so the frame joists will be 2.7m (400mm centres) in the opposite direction if that makes sense. Will construct with joist hangers, noggins and combination of coach and deck screws. Building on flat grass/soil. I'm removing the top layer, up to 50mm, level the soil, lay heavy duty weed control fabric and a layer of gravel. I then intend to sit the frame on paving slabs to raise off the ground. My question really is how many paving slabs do I need to support adequately? One in each corner but then how many in between around the edge of the frame and do I need any under the joists as I read that 2x6 will comfortably span 2.7m. Thanks in advance.