Given that 门店 (lit. "door shop") = "outlet", how do you say "door shop"?
門業公司 or 大門設計 if you are looking for a shop that sells just doors, perhaps designer doors. But most shops carry other items as well, so it is common practice to visit a 門窗公司, 裝修公司, 廚櫃公司, or 木業公司 for the wooden product, or a 五金行 for the metallic bits.