Door Lining Sizes – How to Measure & Choose the Right Depth

Choose a door lining by measuring the finished thickness of the wall where the lining will sit. Include plasterboard, plaster and skim rather than choosing from the stud or block size alone.

Standard softwood door lining sizes

Nominal size	Approx. finished size	Best match
32 × 115mm	27.5 × 108mm	Finished walls around 108mm
32 × 125mm	27.5 × 120mm	Finished walls around 120mm
32 × 138mm	27.5 × 132mm	Finished walls around 132mm
32 × 150mm	27.5 × 145mm	Finished walls around 145mm
32 × 175mm	27.5 × 155mm	Deeper finished walls around 155mm

All five sizes are available on our Softwood Door Lining Kit.

Firecheck door lining sizes

Nominal size	Approx. finished size
38 × 115mm	32 × 108mm
38 × 138mm	32 × 132mm
38 × 150mm	32 × 145mm

These sizes are available on our Redwood Fire Door Lining Set. The Firecheck lining uses a thicker redwood section and is machined with a 15 × 4mm groove for a compatible intumescent strip or smoke seal.

Measure the finished wall, not just the stud

A 89mm stud does not automatically mean one lining depth because the finished wall also includes the boards and finish on each side. The same applies to masonry walls: old plaster, new skim and uneven finishes can change the real thickness.

Measure the wall you will actually be finishing against.

If the lining is slightly too narrow, around 2mm is normally manageable

Where the frame is being painted, a very small difference can usually be dealt with when filling and finishing around the architrave. Once the mismatch becomes larger, the cleaner approach is normally to move up a size.

Once the lining is fitted, finish the doorway with architrave and carry the same profile around the room with matching skirting boards and architrave.

If the lining is too wide, plane the larger lining down

Choosing the next stocked depth up gives you timber to work with. A lining can be reduced to suit; making a significantly narrow lining wider is much less tidy.

The reversible head suits 2'6" and 2'9" internal doors

Our lining sets use a reversible head machined for 762mm (2'6") or 838mm (2'9") doors. The lining depth is a separate measurement from the door width: choose the door opening from the head, and choose the lining depth from the finished wall.