A door lining is one of those things most people only think about when they're fitting a new door or renovating a room. Get the width wrong and you're either packing out the reveal or cutting down timber on site. Get it right and the door hangs cleanly, the architrave beds flat and the whole thing looks like it's always been there.
This guide covers standard door lining sizes, how to measure for one, which timber to use and a few fitting tips worth knowing before you start.
What is a door lining?
A door lining is the three-sided timber frame that lines the inside of a door opening in a stud wall or block wall. It consists of two vertical legs and a horizontal head, rebated to accept the door. The architrave is then fixed to the face of the lining to cover the gap between the lining and the plaster.
Door linings are different from door frames. A lining is used in internal partition walls where the door opening has no structural load above it. A door frame (also called a door casing or door set) is a heavier construction used in load-bearing walls and external doorways.
Standard door lining sizes
Door linings are sized to match wall thickness. The lining needs to sit flush with the plaster on both sides of the wall, so the width of the lining equals the wall thickness plus both plaster coats.
The door lining sizes we stock, and the wall build-up each one suits:
| Finished width | Lining set size | Suits this wall |
|---|---|---|
| 108mm | 115mm softwood set | Standard 100mm stud wall with plasterboard each side |
| 132mm | 138mm softwood set | Thicker stud wall, or 100mm stud with plasterboard and skim |
| 155mm | 175mm softwood set | 150mm block wall with plaster each side |
Pre-finished oak, walnut and white-primed door frame lining kits are also available in 108mm and 133mm widths (fire-rated and non-fire-rated). If your wall is an unusual thickness, a wider lining can be ripped down on site or ordered to a custom width.
These are the most commonly stocked sizes. If your wall is an unusual thickness, linings can be ordered to a custom width or ripped down from a wider board on site.
How to measure for a door lining
Before ordering, measure the wall thickness at the door opening in three places: top, middle and bottom. Walls are rarely perfectly consistent, particularly in older properties where block sizes varied and plaster has been applied at different thicknesses over the years.
Take the largest measurement and order to that width. A lining that's 2mm too wide can be planed back on site. One that's 5mm too narrow means packing out the reveal and the architrave won't lie flat.
For the door height, standard internal door linings are supplied at 2100mm leg length to suit a standard 1981mm door. If your ceiling is lower or you're fitting a non-standard door height, check the leg length before ordering.
Standard door lining sets are supplied for a 762mm or 838mm door width (the two most common internal door sizes in the UK). The head is cut to length to suit.
Timber or MDF?
Most door linings sold in the UK are softwood or MDF. Both are painted, so the choice comes down to workability and budget.
Softwood is traditional and slightly easier to fix into. Nails and screws hold well, it can be planed on site if needed and it takes paint straightforwardly. It's also marginally more forgiving if the opening is slightly out of square and you need to scribe one of the legs.
MDF gives a flatter, more consistent surface and holds a painted finish well. It's heavier, doesn't like moisture and is harder to nail close to an edge without splitting. For dry internal partitions in new build or renovation work, MDF linings are a cost-effective option.
For period properties or anywhere you're matching existing joinery, softwood is the better choice. It's easier to work with traditional tools and the grain accepts stain and clear finishes if you want a natural look.
Rebate depth and door thickness
The rebate in a door lining is the step that the door closes against. Standard rebate depth is 12mm for a 35mm door and 15mm for a 40mm door. Most pre-made linings are supplied with a 12mm rebate as standard, which suits the majority of interior doors.
If you're hanging a heavier fire door (typically 44mm or 54mm thick), check the rebate depth and lining specification before ordering, as fire doors often require a deeper rebate and may need specific ironmongery.
Fitting a door lining
A few things that make the job easier:
- Check the opening for square before you start. Use a spirit level on both sides and a straight edge across the head. Most openings in block or brick construction are slightly out, so shim as you go.
- Fix the legs plumb first, then cut the head to fit exactly between them. Don't assume the head length equals the door width plus two lining thicknesses — measure the actual gap.
- Use frame fixings or timber screws through the lining into the surrounding structure. Avoid nailing only as linings can work loose over time, particularly in stud walls where the noggings may not align perfectly with the fixings.
- Leave a 2mm gap between the door and the lining on the hinge side and latch side. This allows for paint thickness and seasonal movement.
- Prime all faces before fixing, including the back face. Moisture from new plaster can cause unprimed timber to bow.
For the architrave, our beadings and mouldings range includes ogee, torus and chamfered profiles in softwood and MDF to suit most interior styles.
Where to buy door linings
Door lining sets and individual lining boards are available in our door linings and frames range, with finished widths of 108mm, 132mm and 155mm in stock for next-day delivery across the UK. For pre-finished options, see our pre-finished oak-faced door frame lining kit and pre-finished walnut-faced door frame lining kit. If you need a custom width or a specific leg length, get in touch and we can cut to order.
For full door hardware and associated joinery including windows and doors, take a look at the rest of the range.
Door lining sizes FAQ
What size door lining do I need?
Measure the total thickness of your finished wall, including plasterboard and any skim coat on both faces, then choose a lining that matches. A standard 100mm stud wall with plasterboard usually needs a 108mm finished lining; add a plaster skim each side and you are closer to 132mm.
What is the standard internal door lining size?
For internal stud partition walls the most common finished widths are 108mm and 132mm. Block walls with plaster typically use a 155mm lining. Nottage Timber stocks softwood lining sets in all three of these finished widths.
What's the difference between a door lining and a door frame?
A door lining is a lighter three-sided timber frame used in internal stud or partition walls where there is no structural load above the opening. A door frame (or casing) is a heavier construction used in load-bearing walls and external doorways.
Can a door lining be cut down to size?
Yes. If your wall is an unusual thickness, a wider lining can be ripped down on site to the exact width you need, or ordered as a custom width.