Inside Interior Doors
Shopping for a paint-ready interior door can be confusing, since you can’t see what’s underneath the primer. If a traditional wood door (generally pine or poplar) is what you’re after, you’ll have to special-order it—and expect it to expand and contract with changes in humidity. Here’s how other interior doors are built today.
1. SOLID/HOLLOW CORE
Molded MDF skins cover the front and back of a glued-together wood or MDF frame; the void is filled with an OSB core for sound absorption and heft—or, in some cases, a polyurethane foam core to reduce the weight. Hollow-core doors are made the same way, with no filler in the void or just a cardboard honeycomb to prevent flexing.
2. SOLID STILE AND RAIL
Engineered or solid wood (or occasionally MDF) makes up the stiles and rails; they are then held together with glue and dowels. Panels are usually MDF and have crisper milled details than molded doors; their skins are either wood veneer or a smooth layer of MDF. These are heavier and more expensive than so-called solid-core doors.
3. CARVED MDF
To replicate the look of a traditional raised panel, two solid slabs of MDF are glued together, then the faces are detailed with a router bit. Since the panel, rails, and stiles are one piece, the door costs less than a solid-wood version with layers of applied molding. A strip of wood is added to the hinge side for better screw retention.