Hi, I'm looking to build decking and I've just ordered 2x4" joists (C16, pressure treated to BS8417) and want to make sure it's ok for my current plan or should I change for 2x6s or put in more support? The joists are within 30cm OC and have lots of noggins and raised by 40-60mm from the ground using Jouplast Adjustable Decking Risers, which I will use 4-6 on each joist. The decking area will be 5.5m x 3.6m. Current plan of the joists & decking are attached (doesn't have the risers in the plan). Any suggestions welcome! Thanks!