The internal wall-lining kit is a series of TrueCore® steel framing noggins and fastenings that make it faster and easier to attach plasterboard or similar wall-lining material to the TrueCore® structural steel building frame. Wall-lining kits are sold in various lots to suit different sizes of flatpack habitable steel building kits. For example, a flatpack habitable steel building kit of 60m2 would require 2x 30m2 lining kits for the internal lining of perimeter walls. Alternatively, the builder can make their own timber noggins and use suitable fixings.