low level deck

[Ben26]

Hey community iam looking at advice on building a low level single frame deck in my back yard. It will be 6mx5m.

Plans so far are to use 140x45 h3 timber for the whole frame using 12x stirups concreted in and where possible 90x90 as posts if space allows or bolted directly to the stirups. So far iam planning to bolt one bearer as a ledger board to the brick wall then every 2m out another bearer. In-between use 140x45 on joist hangers with joist hanger screws also spaced every 450. Do I need to double up the middle bearers? Or is a single 140x45 ok? Pretty much exactly as the picture from another members post I found. Will be over dirt. Should give me roughly 150-250 clearance under the deck for airflow. Planning on using 90x19 merbau as decking boards.