Building a Stud Wall: Timber Sizes, Noggins, Fixings & Soundproofing

Summary

Non-loadbearing stud partition walls are one of the most common carpentry tasks in UK domestic work — splitting bedrooms, creating en-suites, adding home offices, or making over a floor plan. The job appears simple but is regularly done badly: walls that flex, walls that transmit sound, walls that were never tied to the structure, and walls that have been built without considering the impact on ventilation, heating, or means of escape.

The Building Regulations position is important to understand. Building a new internal partition wall is generally exempt from Building Regulations notification in its own right, but if the partition wall affects a habitable room's means of escape, ventilation, or fire separation, those regulatory requirements are triggered. Converting a single room into two bedrooms, for example, may trigger Part B (fire) and Part F (ventilation) requirements.

Soundproofing is the most common callback issue. Customers expect privacy between rooms but a bare stud wall with plasterboard each side transmits conversation clearly. Meeting even the minimum requirements of Part E requires mineral wool quilt between the studs — and premium performance requires independent leaf construction.

Key Facts

• Standard stud size (domestic): 75×50mm C16 regularised softwood — adequate for walls up to 2.7m height
• Stud size for walls 2.7m–3.6m: 100×50mm C16 minimum
• Stud centres: 400mm for standard plasterboard (1,200mm/3 = 4 bays); 600mm for 15mm board
• Head plate and sole plate: Same section as studs — typically 75×50mm or 100×50mm
• Noggins: Minimum 75×50mm; fitted at mid-height (approximately 1,350mm from floor); additional noggins at radiator/socket/switch heights and at board joins
• Noggin fixing: Skew-nailed or use metal noggin hangers; minimum 2 × 75mm wire nails each end
• Head plate fixing (to timber joist floor): 100mm screws or nails at 600mm centres into joists — fix to every joist, not just into plasterboard
• Sole plate fixing (to concrete floor): 10mm SDS masonry anchors at 600mm centres
• Sole plate fixing (to timber floor): 100mm screws through board and into joist below; plug and screw between joists
• Plasterboard thickness (stud wall): 12.5mm standard or 15mm for improved sound; two-layer 12.5mm = best performance
• Plasterboard screw centres: 150mm to perimeter, 300mm to intermediate studs
• Standard plasterboard size: 1200×2400mm (or 1200×3000mm for taller walls)
• Sound insulation (bare stud): Approximately 33–35 dB Rw — well below Part E requirement
• Sound insulation (with quilt): 60mm mineral wool quilt between studs achieves approximately 43 dB Rw
• Part E minimum (new build): 43 dB Rw between rooms in purpose-built dwellings [verify current requirement]
• Fire performance: Standard plasterboard gives 30-minute fire resistance; 2 × 12.5mm gives 60 minutes

Quick Reference Table

Detailed Guidance

Marking Out and Setting Up

1. Establish the line of the wall on the floor using a chalk line or laser — check it is square to the room if required
2. Mark the sole plate position; check for any underfloor services using a cable and pipe detector
3. Transfer the line to the ceiling using a plumb bob or rotary laser level
4. Mark the head plate position on the ceiling

Always check: does the partition wall run parallel to or across floor joists? If parallel, the sole plate may fall between joists with no fixings available — additional blocking between joists may be needed before fixing the plate.

Framing Up

Sole plate first: Fix the sole plate along the floor line, leaving a gap only where doorways will be. Do not fit a full-length sole plate and cut out later — it is neater and stronger to frame around the opening from the start.

Head plate: Fix to ceiling joists or noggins between joists. Never just screw into plasterboard ceiling — the head plate must be fixed to structure.

Studs: Measure each stud individually — floors and ceilings are rarely perfectly level or parallel. Cut each stud 3–4mm short for easy fitting; a stud that is too long will push the head plate off its line.

Fixing studs:

• Toenail (skew nail) using 100mm round wire nails — two nails each end, driven at opposing angles
• Alternatively, use metal framing connectors (joist hangers for studs) for neater fixing

Door openings: Frame using trimmer (inner) studs to take the door lining; king (outer) studs; and a head (lintel) over the opening. For stud walls, a 47×100mm or 47×150mm header is adequate for non-loadbearing openings.

Noggins

Fit noggins at:

• Mid-height: Always — prevents studs from twisting and provides a fixing point for pictures and future fittings
• Plasterboard horizontal joins: If boards don't run full height, noggins must support the board edge
• Socket and switch heights: Approximately 350mm from floor for sockets; 1,200mm for switches — fit a double-width noggin (two pieces) to give adequate fixing area
• Radiator positions: Fit a robust noggin at bracket height — a wall-mounted radiator full of water is substantial dead weight
• TV wall mounts: Customer should specify positions before boarding — fit a full panel of 18mm ply behind the boards if the TV position is uncertain

Soundproofing

To achieve useful sound reduction:

1. Fill stud bays with 60mm mineral wool acoustic quilt (e.g. Knauf Acoustic Roll, Isover Party Wall Roll) — not standard loft roll, which is less dense
2. Use two layers of 12.5mm plasterboard rather than one layer of 15mm — the mass law means that two separate layers with an air gap between them outperform a single thicker layer
3. Fix one layer of board directly to the studs; the second layer staggered-joint with grab adhesive and screws
4. For improved performance, use resilient bars (e.g. Gyproc Resilient Bar) fixed horizontally across the studs at 600mm centres; fix the plasterboard to the bars, not directly to the studs. This decouples the boards from the structure and eliminates direct vibration transmission
5. Seal all perimeter joints with acoustic sealant — flanking transmission around the edges of the wall is a major cause of poor acoustic performance

Electrical and Plumbing Runs

• Drill stud centres at mid-height for horizontal cable runs; use 25mm drill in 50mm stud — fits 2× 6mm² T&E cable side by side
• Vertical cable runs in the cavity — no drilling required
• Notching the face of a stud for cables is acceptable for non-loadbearing walls but cover with a steel protective plate
• Plumbing in stud walls requires at least 100mm stud depth — allow for pipe plus insulation plus clearance

Frequently Asked Questions

Does building a stud wall need Building Regulations approval?

Building a non-loadbearing internal partition in an existing dwelling is generally permitted development and does not require Building Regulations approval for the wall itself. However, if the new wall creates a new habitable room (e.g. a bedroom), the new room must comply with Part F (ventilation), Part L (insulation if new window is added), and Part B (means of escape — the room needs an openable window to outside if above ground floor). A building control application may be advisable if you are unsure.

What is the difference between C16 and C24 timber for stud walls?

C16 and C24 are strength grades for softwood timber. C16 is the standard grade used for most domestic stud walls and is widely available and cost-effective. C24 is stronger — used for structural floor joists and roof rafters where span tables require it. For non-loadbearing stud partitions, C16 is entirely adequate.

Can I put a stud wall on a suspended timber floor?

Yes, but you must position the sole plate over a joist or add noggings between joists to create a solid fixing point. If the partition runs parallel to the joists, a single joist may not be adequate — check with a structural engineer if the wall is long and heavy (especially if also adding a masonry veneer or heavy finishes).

How do I get the wall perfectly plumb?

Fit the sole plate and head plate accurately first, using a level and a plumb bob or rotary laser. If both plates are on the same plumb line, every stud should stand plumb automatically. Check each stud with a spirit level as you go — small errors in plate position can accumulate. Use packing shims at the plate fixings if the floor or ceiling is out of level.

How much weight can a stud wall carry?

A standard 75×50mm stud wall with plasterboard both sides can carry normal picture rails, shelves, and standard radiators via noggins. For heavy items — large TVs, kitchen cabinets mounted on an internal partition, heavy bathroom fittings — fit a full sheet of 18mm WBP ply behind the plasterboard, screwed to the studs. This gives a fixing anywhere on the wall surface.

Regulations & Standards

• Building Regulations Approved Document E (Resistance to the passage of sound) — minimum sound insulation requirements

• Building Regulations Approved Document B (Fire safety) — fire resistance requirements, means of escape

• Building Regulations Approved Document F (Ventilation) — ventilation in new habitable rooms

• BS 5268-2 (Structural use of timber) — span and load data for timber members [superseded by Eurocode 5 but widely referenced]

• BS EN 338 (Structural timber — strength classes) — C16 and C24 grade definitions

• Knauf Drywall — Partition Systems Guide — Stud spacing and board specification guidance

• TRADA Technology — Timber Frame Design — Structural timber information

• Building Regulations Approved Document E — Official sound insulation requirements

• first fix second fix — What goes in the wall before boarding

• cable sizing — Cable sizing and protection in stud walls

• waterproofing — Waterproofing a tiled stud wall

• part b fire — Fire resistance requirements