Second Fix Carpentry: Skirtings, Architraves, Doors and Stairs

Summary

Second fix carpentry is where a job either looks professionally finished or doesn't — there's nowhere to hide a bad mitre on a skirting joint or a door hung with an uneven gap the way there is with a stud wall buried behind plasterboard. It's also the stage most affected by what other trades left behind: pipework that wasn't notched cleanly, an electrician's back box sitting proud of the finished plaster line, or a floor that isn't quite where the specification said it would be. A second fix carpenter has to read and adapt to all of that while still hitting tight tolerances on visible joinery.

This article is a consolidated technical reference across the four main second fix carpentry elements — skirting, architrave, door hanging, and staircase finishing. For the broader cross-trade sequencing context (how second fix carpentry fits alongside plumbing, electrical, and heating second fix), see first fix second fix. For deep technical detail on each individual element, see the linked articles in Related Articles below — this piece is the map, not the full territory on any one topic.

Key Facts

• Second fix starts after plastering has dried — typically 5–14 days after skim coat depending on conditions (skim coat), never before the walls have firmed enough to take fixings cleanly
• Skirting standard heights — 100mm, 125mm, 150mm and 175mm are the common UK stock sizes; period properties often specify 150–225mm to match existing profiles
• Architrave reveal — 5–6mm is the standard visible margin between the architrave edge and the door lining, kept consistent on both sides and the head for a professional finish
• Door clearances — 2–3mm at both hinge and leading (latch) side, 2–3mm at the head, 8–10mm at the bottom over carpet, 4–6mm over hard flooring (tile, wood, laminate)
• Standard butt hinge sizes — 75mm or 100mm for internal doors; three hinges (not two) required on fire doors (FD30/FD60) per BS 8214:2016
• Fire door gap tolerance — maximum 3mm around a fire door (sides, head, and meeting point), intumescent-backed hinges and closers required — significantly tighter than a standard internal door
• Staircase regulations (Approved Document K) — max rise 220mm, min going 220mm, 2R+G comfort formula 550–700mm, headroom minimum 2000mm, guarding 900mm alongside stairs / 1100mm on landings, 100mm sphere test for baluster spacing
• Skirting fixing methods — plugs and screws to masonry, adhesive (gripfill/no-more-nails style) plus pins to plasterboard/dot-and-dab walls, or nail gun with 50mm lost-head nails into timber studwork/noggins
• Mitre vs scribe joints — external corners are always mitred (45°); internal corners are scribed (coped) rather than mitred, because scribed joints stay tight even if the wall angle is slightly out of square — see scribing and coping cuts
• Expansion gap — skirting and architrave in MDF need a small allowance for movement; leave joints slightly proud rather than forced tight, and never fully seal a run with silicone at both ends
• Workmanship standard — BS 8000-5 (carpentry and joinery workmanship on building sites) is the reference standard cited for tolerances, fixing methods, and finish quality across all second fix carpentry

Quick Reference Table — Second Fix Carpentry Elements

Detailed Guidance

Skirting boards

Skirting protects the base of the wall, covers the plaster/floor junction, and is one of the most visually continuous lines in a room — any inconsistency in height or gap is immediately obvious.

• Setting height — mark a level line around the room using a laser level rather than measuring up from the floor at each point, since floors are rarely perfectly level
• Internal corners — scribed (coped), not mitred; cut the first length square into the corner, then cope the second length along its profile with a coping saw so it fits over the face of the first. This stays tight even if the wall corner isn't exactly 90° — see scribing and coping cuts for the full technique
• External corners — mitred at 45°, checked with an offcut before cutting the full board, since external wall corners are frequently slightly out of square in older properties
• Fixing to different wall types — masonry needs plugs and screws (or a nail gun with a suitable masonry-rated fixing); dot-and-dab and dry-lined walls need adhesive plus pins, since screwing directly into the dabs alone gives poor grip; timber stud walls take a nail gun straight into the studs and noggins
• Scribing around obstructions — pipework, radiator pipes left by the plumber, and skirting-mounted trunking all need to be scribed around rather than notched roughly; coordinate with the plumber so pipe positions are confirmed before skirting is cut, not after

Architrave

Architrave covers the joint between the door lining and the plastered wall, and sets the finished visual frame around every door opening in the property.

• Consistent reveal — mark a 5–6mm reveal line around the lining using a combination square or a scrap gauge block, and keep it identical on both sides and the head; an inconsistent reveal is one of the most common snagging points on a new-build or refurb
• Mitre joints top corners — both top corners of the architrave are mitred at 45°; check the lining is genuinely square before assuming a factory 45° cut will close tightly
• Fixing — adhesive plus panel pins is standard for MDF/softwood architrave onto a timber lining; pins are punched below the surface and filled before decoration
• Matching existing profiles — in refurbishment work, especially older or listed properties, architrave profile must often match existing mouldings exactly; a mismatched profile installed alongside original mouldings stands out immediately — see listed buildings where consent may also apply

Door hanging

Hanging doors correctly is a combination of accurate clearances, correct hinge positioning, and getting the door to close and latch cleanly without binding.

• Clearances — 2–3mm at the hinge side, 2–3mm at the leading (latch) side, 2–3mm at the head, and 8–10mm at the bottom for carpet (allowing for underlay and pile) or 4–6mm over hard flooring
• Hinge position — rule-of-thirds positioning is standard: top hinge roughly one-ninth of the door height from the top, bottom hinge roughly one-sixth from the bottom, with a third (intermediate) hinge centred between them on fire doors or heavier doors
• Hinge size — 75mm butt hinges for lightweight internal doors, 100mm for heavier or fire-rated doors; always fit the number and type of hinge specified for a fire door — reducing from three hinges to two, or substituting standard hinges for intumescent-backed hinges, invalidates the fire rating
• Fire doors — FD30 and FD60 doors require intumescent strips (either applied to the frame or built into the door edge), certified fire-rated hardware, and self-closers where specified; the maximum gap tolerance drops to 3mm all round, tighter than a standard door — see door hanging step by step and door frame fitting for the full step-by-step method
• Ironmongery — handles, latches, and locks are fitted after the door is hung and closing correctly; test the latch engages cleanly with the door closed under normal (not forced) pressure before considering the door finished
• Floor level dependency — never hang doors before the finished floor covering is confirmed or laid; a door hung to an assumed floor level that changes (e.g. underfloor heating build-up, a thicker floor covering than specified) will need the bottom re-cut, which is avoidable rework

Staircase second fix

While the staircase carcass (strings, treads, risers, newel posts) is generally first fix work, the visible finishing elements — balustrade, spindles, handrail, and newel caps — are second fix, completed after plastering and often after the main flooring is down.

• Regulatory geometry (Approved Document K) — maximum rise 220mm, minimum going 220mm, with the "2R+G" comfort formula (twice the rise plus the going) falling between 550mm and 700mm for a comfortable stair; maximum pitch 42°
• Headroom — minimum 2000mm measured vertically over the full width of the stair, reducing to 1900mm in loft conversions under specific conditions
• Guarding height — minimum 900mm alongside a flight, 1100mm on landings
• 100mm sphere rule — no gap in the balustrade (between spindles, or under the bottom rail) should allow a 100mm sphere to pass through, preventing small children from getting a head or limb trapped
• Handrail — required on at least one side of stairs under 1m wide, both sides is common practice and sometimes specified for wider stairs or where accessibility standards apply; fixed to wall studs/noggins (never to plasterboard alone) or newel-to-newel via brackets
• Newel post fixing — must be fixed securely to the structural stair carcass, not just to the finished floor covering, since the newel post carries significant lateral load from anyone leaning on the handrail
• Full technical detail — see staircase construction for stringer marking, assembly sequence, and stair regulation cross-references, and staircase regs for the full regulatory breakdown

Window boards

Often grouped with second fix carpentry even though timing can vary — window boards are sometimes fitted at first fix (before plastering, scribed into the reveal) and finished/trimmed at second fix, or fitted entirely at second fix depending on the sequence used.

• Expansion allowance — MDF window boards need roughly 3mm per 600mm of length allowed for movement; a board fitted bone-tight wall-to-wall in a wide window opening will bow or crack the plaster reveal as it expands
• Sill sealing — a silicone bead seals the board to the sill beneath, preventing water ingress finding its way behind the board from any window seal failure
• Scribing to the reveal — where the wall isn't perfectly square, scribe the board edge to the plaster reveal with a coping saw for gaps under 10mm rather than relying on caulk to fill a visible gap
• Full detail — see window boards

Coordinating second fix carpentry with other trades

Second fix carpentry deliberately runs after electrical and plumbing second fix in the standard sequence, for good reason:

• Skirting is scribed around radiator pipes and any surface-mounted trunking left by the plumber and electrician, not the other way around
• Architrave and door hanging should follow confirmation of the finished floor level, which is often set by the flooring contractor
• Kitchen fitting (a related but usually separately priced second fix carpentry task) needs plumbing and electrical rough positions confirmed first
• Snagging at handover frequently traces back to second fix carpentry being rushed to hit a completion date while waiting on other trades — build float into the programme rather than compressing the carpentry stage

Frequently Asked Questions

Why is the internal corner on skirting scribed rather than mitred?

Internal wall corners in real buildings are very rarely exactly 90°. A mitred internal joint (two 45° cuts) will show a visible gap wherever the actual angle is off-square. A scribed (coped) joint — cutting the second piece along the profile of the first with a coping saw — stays tight regardless of the exact corner angle, which is why it's the standard method for internal skirting and architrave corners in the UK.

Can second fix carpentry start before the walls are fully dry from plastering?

No — fixing skirting, architrave, and doors into walls that are still drying risks fixings pulling loose as the plaster continues to shrink and cure, and any adhesive-fixed elements (architrave, some skirting) may not bond properly to a still-damp surface. Allow the plasterer's stated drying time (typically 1–3 weeks depending on conditions) before starting second fix carpentry.

What's the difference between a standard internal door and a fire door in terms of second fix work?

A fire door (FD30/FD60) has a tighter gap tolerance (3mm all round vs 2–3mm sides/head, 8–10mm base on a standard door), requires three hinges rather than two, needs intumescent strips (either frame-fitted or door-edge-integrated), and typically a certified self-closer. Fitting a fire door with standard-door clearances or hardware invalidates its fire rating even if it looks correctly hung.

How much movement should I allow when fitting MDF skirting and architrave?

Don't force joints bone-tight, especially on long runs — leave a slight allowance and avoid fully sealing both ends of a run with adhesive or silicone, which prevents natural expansion and contraction and can cause joints to open or bow over a heating season.

Does second fix carpentry need building control inspection?

Not typically for skirting, architrave, and door hanging on standard domestic work, but staircase alterations (new stairs, or changes to an existing staircase's geometry or guarding) usually do fall under Building Regulations and should be checked against Approved Document K requirements and, where structural, inspected by building control alongside the wider project.

Regulations & Standards

• Building Regulations Approved Document K (Protection from falling, collision and impact) — staircase geometry, guarding heights, and baluster spacing

• BS 8000-5 — workmanship on building sites: code of practice for carpentry and joinery, covering fixing methods and finish tolerances for skirting, architrave, and general joinery

• BS 8214:2016 — code of practice for fire door assemblies, covering gap tolerances, hinge requirements, and intumescent detailing for FD30/FD60 doors

• Building Regulations Approved Document B (Fire Safety) — fire door provision requirements in escape routes and compartmentation

• Building Regulations Approved Document Q — security requirements for doors and windows in new dwellings, relevant to external door hardware specification

• Planning Portal — Approved Document K — protection from falling, collision and impact, staircase regulation detail

• BSI — BS 8000-5 — carpentry and joinery workmanship standard

• BSI — BS 8214:2016 — fire door assemblies code of practice

• CITB — Carpentry and Joinery NVQ Guidance — industry training standards for second fix technique

• Carpentry Prices Guide — Checkatrade — UK market pricing reference

• first fix second fix — full cross-trade sequencing and pricing overview for first fix and second fix stages

• skirting architrave — detailed skirting and architrave fitting technique

• door hanging step by step — full internal door hanging method including fire door detailing

• door frame fitting — door lining/frame fitting technique preceding second fix architrave

• staircase construction — stringer marking, assembly sequence, full staircase build technique

• staircase regs — full Approved Document K regulatory reference

• scribing and coping cuts — the coping technique used for internal skirting and architrave corners

• window boards — window board fitting and expansion detailing