building shed shelving

[b21playa]

hi all

i currently have metal shelfing along 1 wall (5m) from floor to 2.5m tall, br want to building some of my own out of wood as these are not deep enough which means many boxes wont fit on them

what is the best and cheapest wood to use to building this

thanks in advance

 

[foxhole]

If the shed does not suffer from damp then mdf [18mm].
White conti type board is also cheap but not as strong.