Our Interior doors In terms of construction, panel doors differ significantly from frame doors. The only similarity is the border, which consists of two vertical and two horizontal elements made of MDF or solid wood. In a frame door they are visible at first glance - in a panel door they are hidden under a one-piece HDF board. Both structures, as they were designed with care and then manufactured using state-of-the-art technology, provide adequate strength and resistance to the effects of harmful factors.