You can't fasten a ledger to most structural insulated panels, so if you want to add a deck to a SIPs house your best bet is to build a freestanding deck and anchor it to the structure or foundation with special metal brackets.
You can beef up the outer skin, but the best solution might be supporting the deck independently.
Be sure your installation isn't subject to wind or seismic loading.
Here's why you often see these "ghost stripes" on SIPS roofs.
