Question: what is the difference between d4 and d5 vinyl siding?
Answer: Various Types & Textures of Vinyl Siding These terms mean that each piece of siding has the appearance of 2 or 3 pieces of lapped wood. Common sizes include double 4”, double 5”, double 6” and triple 3”. You'll typically see them called D4 for double 4”, D5 for double 5” and so forth.