Need more space? Got a dingy unfinished room? You can quickly transform that space into something usable and comfortable. We take a closer look at it as well as some alternatives. Interior Door Installation Cost Home Depot Cost Of Interior Door Installation Interior Door Installation Cost Best Style is one way to turn a dingy unfinished room into additional space that's attractive and comfortable. It does this by applying their expertise in building science and system design to the standard below-grade home design.