Summary
En-suite installations are a frequent value-add project for UK homeowners — they convert wasted bedroom corner space into a functional second bathroom that increases sale value by 5-10% according to most estate agent benchmarks. The pricing logic is similar to a small bathroom but with three critical additions: stud wall construction (if forming a new room within a larger bedroom), waste pipe routing (often the biggest hidden cost), and ventilation (window vs. mechanical extract).
The most common pricing pitfall is treating an en-suite as "half a bathroom price." It's not. The fixed costs — building inspection, skip hire, plumber and electrician call-out, tanking — are similar whether you build 3m² or 6m². Spread across a smaller area, the £/m² rate is naturally higher than a full bathroom. A 4m² en-suite at £6,500 is £1,625/m²; a 6m² bathroom at £8,000 is £1,330/m². This is normal.
This guide covers en-suite installations across the four standard scenarios — converting bedroom corner to en-suite, building en-suite into loft conversion, replacing existing en-suite, and adding en-suite to extension/loft. For full bathroom guidance see full bathroom installation pricing guide.
Key Facts
- Compact en-suite (3-piece + corner shower) — 3-4m² typical; £4,500-£8,500
- Standard en-suite (3-piece walk-in shower) — 4-6m² typical; £6,500-£12,000
- Premium en-suite (4-piece, bath + shower) — 6-9m² typical; £10,000-£18,000
- Stud wall construction — 75mm or 100mm timber stud + plasterboard both sides + insulation; £80-£120/linear m
- Door + frame + ironmongery — £150-£400
- Compact corner shower enclosure (800-900mm) — £200-£500
- Walk-in shower with screen (1000-1200mm) — £350-£900
- Compact basin (cloak-style 350-500mm) — £80-£200 supplied
- Wall-hung basin (slim profile) — £150-£400 supplied
- Compact toilet (back-to-wall short projection) — £200-£500 supplied
- Wall-hung toilet + cistern + frame — £400-£900 supplied
- Thermostatic shower mixer + head — £200-£800 supplied
- Electric shower — £150-£400 supplied
- Soil pipe rerouting — £400-£1,200 typical
- Macerator pump (Saniflo, Saniflow) — £300-£700 supplied; allows compact installs without gravity-fed waste
- Mechanical ventilation extractor (Building Regs Part F) — £40-£200 supplied; mandatory if no window
- Tile cost (mid-range porcelain) — £35-£70/m²
- Floor area covered with tile — 3-6m²; wall area 6-12m²
- Tanking — £15-£30/m²; required for tiled shower area
- Plumber — typically 4-5 days; £1,000-£1,800
- Tiler — 2-3 days; £400-£840
- Electrician — 1 day; £280-£380
- Carpenter — 1-2 days (if stud wall); £200-£560
- Decorator — 0.5 day; £90-£140
- Building Regulations — Part F (ventilation), Part G (sanitation), Part P (electrical), Part B (escape route if affecting bedroom)
- Macerator regulations — Building Regulations Approved Document H Section 1; must be installed correctly; only for restricted use (no kitchen waste)
- VAT — 20% standard
Quick Reference Table
Spending too long on quotes? squote turns a 2-minute voice recording into a professional quote.
Try squote free →| En-Suite Type | Size | Spec | Cost Range (Regional) | Cost Range (London) |
|---|---|---|---|---|
| Compact 3-piece in bedroom corner | 2.5-4m² | Mid-range, no stud walls | £4,500-£7,500 | £5,800-£9,500 |
| New en-suite with stud walls | 3-5m² | Mid, partition included | £6,500-£10,500 | £8,000-£13,000 |
| Loft conversion en-suite | 3-5m² | Compact, vertical pipe routing | £6,500-£11,000 | £8,500-£14,000 |
| Walk-in shower en-suite | 4-6m² | Mid-premium | £7,500-£13,000 | £9,500-£16,000 |
| Bath + shower 4-piece | 6-9m² | Premium | £11,000-£18,000 | £14,000-£23,000 |
| Wall-hung toilet + premium fittings | 4-6m² | High-end | £11,500-£19,000 | £14,500-£24,000 |
| En-suite refit (like-for-like) | 3-5m² | Mid-range, no structural | £4,000-£7,500 | £5,500-£9,500 |
Detailed Guidance
Stage Breakdown
Day 1-2: Strip and discovery
- If existing en-suite: strip sanitaryware, tiles, ceiling
- If converting bedroom corner: lay floor protection, set out stud walls
Day 2-4: Stud walls and rough carpentry (if applicable)
- 75mm or 100mm CLS stud at 400mm or 600mm centres
- Plasterboard both sides, taped and jointed
- Door frame fitted
- Insulation between studs (acoustic and thermal)
Day 4-7: First-fix plumbing and electrics
- Supply pipes to basin, shower, toilet
- Waste pipes: 110mm to toilet, 40mm to basin and shower
- Soil stack connection or macerator pipe route
- Lighting circuits (Part P certified)
- Extractor fan power and ducting
- Underfloor heating mat (if specified)
Day 7-10: Tiling
- Floor tile, wall tile
- Tanking applied before tiling in wet areas
Day 10-12: Second-fix and snag
- Hang and connect sanitaryware
- Connect shower system
- Fit doors and ironmongery
- Silicone bead
- Customer handover
Total: 7-12 working days. Customer's other bathrooms remain in service during en-suite work.
The Soil Pipe Problem
In ~30% of en-suite projects the soil stack is more than 5m from the proposed en-suite. Options:
Option 1: Extend existing soil pipe
- 110mm uPVC waste pipe extension; fall 1:40 minimum (BS EN 12056)
- Must terminate to existing soil stack or new stack
- Cost: £400-£1,200 depending on access (floor lifting, ceiling work, vent terminal)
Option 2: New external soil stack
- 110mm uPVC stack on external wall
- Vent terminal above roof line
- Cost: £700-£1,800 supplied and fitted
Option 3: Macerator pump (Saniflo)
- Compact pump in WC unit; pumps waste to existing soil stack via 22mm or 32mm pipe
- Lower install cost: £400-£800
- Higher service cost: pump replacement every 7-15 years (£250-£500)
- Restrictions: not suitable for high-volume use, no kitchen waste
- Customer education on use important — wrong waste damages pump
For most en-suites, Option 1 (extending soil pipe) is the right answer; Option 3 (macerator) suits truly difficult locations like loft conversions or basements with no gravity drainage. Always assess soil pipe options at quote stage.
Stud Walls — Building a New En-Suite
When converting bedroom corner to en-suite, expect to build 2-3 stud walls (one or two new walls plus the door):
- 75mm CLS timber stud at 400mm centres for non-load-bearing; 100mm for any acoustic-sensitive separation
- Plasterboard both sides (12.5mm standard; 12.5mm moisture-resistant on the wet side)
- Insulation between studs: 50mm mineral wool for acoustic (helpful for bedroom side)
- Door pocket or hinged door; pocket doors take more space planning
- Skirting and architrave to match bedroom
- Decoration: mist coat + 2 coats on bedroom side; tiles or paint on en-suite side
Cost per linear m: £80-£120 supplied and fitted. A typical 4m² en-suite requires 4-6m of new stud wall = £400-£700 in carpentry plus £200-£400 in plasterboard, mud, paint, and decoration.
Ventilation — Building Regs Part F
Every en-suite must have mechanical extract ventilation if there is no openable window with sufficient area. Requirements:
- Extract rate ≥15 L/s for bathroom/en-suite (BS EN 13141)
- Located in or near the wet area
- Discharge to outside via ducted vent
- 15-minute overrun timer after light switch off (or humidity sensor) is standard practice
- For loft en-suites, ducting to outside via gable end or fan-assisted ridge vent
Cost: £40-£200 for fan, £80-£200 for ducting and termination, £80-£180 for fit. Many builders supply MVHR-ready en-suites in modern builds; for retrofit, dedicated extractor fan + ducting is the standard.
Loft Conversion En-Suite — Special Considerations
When the en-suite forms part of a loft conversion, additional complications:
- Roof pitch limits headroom — at least 60% of usable area must have 1.5m+ headroom under Building Regs Part K; en-suite frequently sits in the lower headroom area
- Soil pipe via existing stack — usually requires routing through ceiling/wall void
- Compact suite — short-projection toilet, compact basin, corner shower
- Plumbing access — supply pipes routed through floor void below
- Heating — towel radiator typical; underfloor heating where space allows
See also loft conversion pricing guide for the wider loft context.
Pricing Walkthrough — Compact 3.5m² En-Suite, Mid-Range, Regional
| Item | Cost |
|---|---|
| Compact suite (Burlington Cloak + close-coupled WC + small basin) | £600 |
| Thermostatic shower mixer + head + 900mm corner enclosure | £550 |
| Mid-range porcelain tile (3.5m² floor + 8m² wall = 11.5m² × £55/m²) | £635 |
| Tile adhesive + grout + tanking | £180 |
| Stud walls (4m linear) + plasterboard | £600 |
| Door + frame + handle | £180 |
| Extractor fan (Building Regs) | £100 |
| Compact towel radiator | £130 |
| Electric UFH mat (3.5m²) | £140 |
| Saniflo macerator pump | £450 |
| Plumber 4 days | £1,200 |
| Tiler 2 days | £480 |
| Electrician 1 day | £320 |
| Carpenter 1.5 days | £360 |
| Decorator 0.5 day | £100 |
| Sundries (silicone, fixings, sealant) | £100 |
| Skip hire | £300 |
| Building Notice + inspection | £200 |
| Margin 20% | £1,205 |
| Total | £7,628 |
Where Builders Lose Money
- Soil pipe rerouting underestimated — biggest single cost variable
- Stud wall not in original quote — customer requests change to room layout
- Macerator chosen too easily — long-term maintenance cost shifts to customer; build-out before quote
- Ventilation duct routing — long runs through joist voids; allow time
- Bedroom decoration — stud wall side often needs decoration to match existing bedroom
- Floor levelling — bedrooms often have uneven floors; en-suite tile requires self-levelling screed
- Loft / restricted access — material handling and labour productivity drop 20-40% in restricted access
Frequently Asked Questions
Do I need planning permission for an en-suite?
No, internal alterations like adding an en-suite are permitted development. Building Regulations approval is required for: drainage (Part H), ventilation (Part F), electrical (Part P), sanitation (Part G). Building Notice or competent person scheme certification covers this.
Can I use a macerator for the toilet?
Yes, in restricted scenarios where gravity drainage is impractical. Saniflo and similar macerators are widely used in basement conversions, loft en-suites and tight access spaces. Trade-offs: 7-15 year pump life; restricted waste types (no kitchen, no nappies, no wipes); 5-year servicing recommended. Quote the maintenance cost as part of long-term ownership.
How long does an en-suite installation take?
A like-for-like refit: 7-10 working days. A new build-out from bedroom corner: 10-12 working days. Loft en-suite as part of conversion: typically 5-7 days within the longer loft project. Customer can usually retain access to other bathrooms during work.
Will my mortgage / sale be affected by an en-suite?
Adding an en-suite typically increases property value 5-10% according to most estate agents — usually more than the install cost. Mortgage lenders see it as standard improvement. Insurance should be notified of additional sanitary fittings. No specific tax implications.
What's the most space-efficient en-suite layout?
For a 3m² space: corner toilet, wall-hung basin (350mm), and 800mm corner shower. Items arranged in an L along two walls; door swings into bedroom or pocket door. For 4m²: same but with 900-1000mm shower or compact bath. Avoid centred door positions that waste corner space.
Can the en-suite share plumbing with the bathroom?
Yes — both connect to the same hot and cold supply and the same soil stack. Pipework needs to be sized for combined demand (typically 22mm hot/15mm cold to en-suite from main bathroom supply). Simultaneous shower use in two rooms requires combi boiler capacity of 30kW+ or a system with cylinder.
Regulations & Standards
Building Regulations 2010 — Part F (ventilation), Part G (sanitation, hot water safety), Part P (electrical safety), Part H (drainage), Part B (escape routes through bedrooms)
BS 6700:2006 — Water supply services
BS 7671:2018+A2:2022 — Electrical installations (Part 701 — bath/shower rooms)
BS EN 12056 — Gravity drainage systems
BS EN 13141 — Mechanical ventilation
WaterSafe — Water Industry Approved scheme for plumbers
NICEIC / NAPIT — Electrical competent person schemes
Saniflo — manufacturer guidance for macerator installation under BS EN 12050-3 (macerating wastewater lifting plants for limited applications)
Saniflo UK — macerator technical specs
full bathroom installation pricing guide — full bathroom context
wet room pricing guide — wet room alternative
shower installation pricing guide — shower-only installs
loft conversion pricing guide — loft en-suite context
cylinder replacement pricing guide — hot water for additional bathroom
underfloor heating wet pricing guide — UFH option