I'm going to build a 5x5 m deck that won't be loaded with anything heavier than a grill, a large load of beer, and a bunch of happy people. At one end, there is a stable concrete foundation to which I can attach post anchors for the wooden beams. Away from the concrete foundation, there is a flat grassy area, but the last 2 meters, the grassy area slopes upward, and it is necessary to dig out a bit to make the deck level. I have a few questions:
1. What is a good distance between the wooden beams running from the concrete foundation towards the slope, and what dimension should they have?
2. Is it sufficient for each wooden beam to rest on 3 points (2.5 m between the points)?
3. On the framework, I'm planning to have transverse thinner beams with cc60, on which I will then lay the deck. What dimension should these beams have?
4. On the slope where it needs to be dug out, I assume there should be some form of retaining wall to prevent the soil from sliding over the deck when it rains, etc. What is the simplest way to do this? I guess it's about 50-60cm high. Are hollow cinder blocks that are secured with rebar a good solution? To increase stability, the bottom cinder blocks can be placed with the long side away from the slope.