Is it better to use ply or cedar for remodeling carpentry? I've heard that fir is easy to be knocked down

Fir is mostly spliced boards, multi-layer boards are mostly joinery or ecological boards. It depends on what kind of effect you want, fir wood is generally used for direct painting varnish kind of process, pay attention to the kind of ecological kind of feeling. And multi-layer board is used for paint-free board or finish bottom surface spray white paint effect, if you want to do the finish bottom not recommended with fir, in addition to the high cost of no other benefits, and easy to deformation. If you want the feeling of the original ecological and feel that the fir is afraid of bumping you can use oak, oak wood is much harder than fir.