If you are the owner (maybe general contractor too) then the building under construction is the inventory - all the materials and labour inputs become part of that one item. Prior to completion its a special type of inventory know as work-in-process (WIP), which is classed separately from 'normal' inventory that is ready-to-sell.
Theres a entire subset of QB practises and proceedures related to construction accounting. You need to learn how to handle progress billing (in and out), holdbacks & releases, loan draws, WIP inventory, WCB registrations, contracor tax reporting etc, etc.
Put some time aisde for heavy reading - it is a lot.
