I'd like to extend my under-house workshop by removing some piers and excavating the existing sandstone bed-rock. I require a design to ensure the subfloor can support the property above and allow the piers to be removed. A detailed design is required to take to a local engineer for sign-off.
I've done detailed measurements and attached a Sketchup diagram that includes the existing layout, with the new proposed boundary marked. The house is a single storey timber framed property with a tile roof.
Happy to provide further details if required.