Looking at decking my back yard this will be 4.8m X 4.8m

I have around 13cm height to play with, the deck is over soil, I wanted to avoid escavating

My plan was to run 90 X 90 TP H4 bearers, resting on stirrups at every 1200mm. Then running the decking straight onto the bearers. Running the bearers at 400mm centres

This leaves me needing to run 13 bearers with 50 odd stirrups

I am not to worried which decking i use, So m questions are

Can i get away with a smaller bearer?
which decking will allow the greatest span? which will decrease my bearers required

Am on a strict budget so trying to work out what is needed

Any help is appreciated

Thanks


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