Wooden Door Frames: Steel, Solid Wood or MDF?

When choosing a room door, most of the time goes into the colour and design of the leaf, yet it is the wooden door frame that keeps the door true, seals out sound and resists warping. A good door on a crooked or ill-fitting frame will never close properly. Here we compare the three frame types most common in residential buildings in Iran and the wider region.

Steel frames: common, but not always the best

In many buildings, a steel frame is set in place during the structural stage, as the walls go up, and is then plastered and painted around. It is strong, inexpensive and impact resistant, but it has drawbacks:

• If it is not set plumb and square during construction, correcting it later is almost impossible, and the wooden leaf has to be fitted to its error.
• In bathrooms and kitchens, the bottom of a steel frame rusts and the paint lifts.
• Next to a refined wooden leaf it looks like building hardware and clashes with wooden interiors.
• Without a rubber gasket the door clacks against metal and the gap lets sound through.

Wooden frames and MDF frames

A wooden frame, in solid timber or veneered engineered wood, is installed after plastering and before the final floor, and matches the leaf in colour and material. Because it is made together with the leaf in the workshop, dimensions and hinge and lock positions line up. For bedroom doors and spaces where appearance and acoustics matter, this is the usual choice.

Veneered MDF or HDF frames mostly come with pre-hung doors. They are lighter and cheaper but more sensitive to moisture: if the bottom touches a wet floor, it swells. In bathrooms, use moisture-resistant timber, or keep the frame foot clear of the floor and seal the cut edges.

Size the frame to the finished wall thickness, not the brick thickness on the drawing.

Details that reveal a quality frame

• Width matched to the wall: walls end up with varying thicknesses once plaster and tiles go on. The frame should match the finished wall or have adjustable architraves that cover the difference.
• A gasket groove: the rubber strip set into the frame softens the closing sound and seals the gap; in bedroom doors the difference is noticeable.
• Plumb installation: the frame is set with wedges and foam or screws at three points on each side. Filled with foam alone, without wedges, the foam pressure can bow a side.
• Finished floor level: before installation you need to know whether the floor will be parquet or tile and how much it will rise; otherwise the gap under the door ends up too big or the door drags on the floor.

If a steel frame is already in place and you do not want to remove it, it can be clad in wood to match the leaf, provided the frame itself is plumb. We have listed common measuring and fitting errors in common wooden door installation mistakes.

Which one should you choose?

If the building is still at the structural stage and a wooden interior is the goal, the opening can be left ready with its lintel instead of a steel frame, and the wooden frame fitted after plastering. If a sound, plumb steel frame already exists, wooden cladding is the lower-cost route. For simple pre-hung doors an MDF frame is enough, as long as it is not used in a wet area. In every case, measuring after plastering and coordinating with the finished floor level matter more than the frame material.