I’d have them make a Dungeoneer test to negotiate rough stairs and allow Laborers to assist by managing the heavy loads and doing “bucket brigade” style teamwork to get that shit upstairs…
It wouldn’t cost a check to carry things to town, btw. That’s part of the adventure phase. You might even earn a check while carrying heavy stuff (if you’re a halfling, which is the best thing to be). Although upon re-reading, I think you meant “test.”