A 12m² luxury master ensuite spa bathroom build for an affluent homeowner couple in Wilmslow, Cheshire — floor reinforced for the freestanding cast-iron bath loading, full Schluter Kerdi sheet tanking, electric underfloor heating throughout, large-format 1200×2400mm marble-effect porcelain panels to walls and ceiling book-matched on the bath wall, freestanding 1.7m cast-iron Aston Matthews Belmont double-ended bath on traditional ball-and-claw feet, 1m×1m steam shower with Hansgrohe Raindance E rainfall head plus four body jets and a Helo HSXS 60 steam generator in a sealed enclosure, bespoke recessed niches with concealed warm-white LED, chromotherapy lighting in the shower zone and around the bath, designer Hansgrohe AXOR Citterio brassware, bespoke walnut-top double-basin vanity unit, Vogue UK heated towel rail, and a Lutron-style 5-scene dimmable lighting control. Five-week programme delivered against fixed price; first soak Friday evening of handback.
An affluent homeowner couple in Wilmslow, Cheshire — a busy professional couple with grown children, who had recently completed a substantial whole-house renovation of their detached SK9 home — commissioned the rebuild of their tired 1990s master ensuite as a 12m² spa-quality bathroom suite. The brief was drawn from a series of high-end UK boutique hotel stays they had enjoyed: a freestanding cast-iron bath as the room's centrepiece, a steam shower with rainfall and body jets to feel like the spa floor at the hotel they liked best, marble-effect porcelain to ceiling for the continuous flow of stone they had admired in the photograph they had saved on their phones, and the kind of lighting and chromotherapy that turns a bathroom into a place where you actually want to spend forty minutes at the end of a working day. Programme contractually fixed at 5 weeks; couple decanting between their guest ensuite and the family bathroom for the duration.
We were one of three contractors invited to quote. Our price came in second by approximately £1,800 against the leading offer. We won the work because our quotation was the only one to (a) include a structural floor survey at quotation stage with priced joist doubling and a 6mm steel ply for the cast-iron bath loading inside the contract sum rather than as a "subject to structural survey" provisional, (b) propose a steam-enclosure pressure test as a contractually-defined hold-point before brassware commissioning — not just a tanking flood test — because steam vapour escapes through gaps that water cannot reach, and (c) engage the specialist large-format porcelain installer (the same fixer we used on the Birmingham Colmore Row HQ Fit-Out heritage joinery interfaces earlier in the year) at procurement stage with a tile-lippage tolerance held to 0.5mm across all panel-to-panel junctions on the 1200×2400mm porcelain.
Practical completion was certified on the contracted Friday afternoon. The Hansgrohe AXOR Citterio brassware was commissioned, the Helo steam generator was tested and live, the chromotherapy was scene-programmed against the homeowners' preferences (a warm-amber sunrise scene for morning, a cool-blue calm scene for evening), the underfloor heating was running at the homeowners' preferred 24°C, and the cast-iron bath was filled with hot water at 4pm Friday for the first time. The wife told us, when we left, that she would be in the bath at half past six.
The brief came from the homeowner couple directly across four pre-construction sessions, drawn from hotel reference photographs, product wishlists and the way they actually use a bathroom at the end of a working day. Priorities, in their stated order:
A 5-week luxury master-ensuite spa build is a different discipline from an accessibility-led wet-room or a full-house modernisation. The freestanding cast-iron bath demands a structural floor that can take its loading; the steam shower demands a sealed enclosure that retains vapour as well as water; the large-format porcelain demands a specialist installer and a tile-lippage tolerance that ordinary tilers can't meet; the chromotherapy and lighting scenes demand commissioning patience to tune to the homeowners' preferences. Every constraint had a workaround that had to be planned before site possession.
The Aston Matthews Belmont 1.7m cast-iron bath weighs 130kg empty; with 250 litres of water and an adult bather it carries a 380kg point load, distributed across four ball-and-claw feet on a 1.7m×0.75m footprint. We commissioned a structural floor survey at quotation stage with a structural engineer walking the existing 195mm timber-joist span on a 400mm centre. The recommendation: joist doubling on the two joists immediately below the bath position, plus a 6mm steel ply spread plate spanning across three joists to distribute the point loads. Both costed inside the contract sum at quotation; installed in week 1 before tanking and tiling commenced.
Steam vapour escapes through gaps that water cannot reach. The 1m×1m steam shower required a sealed full-height glass enclosure (silicone-sealed at every junction including head, jambs, threshold and the ceiling), porcelain panels carried to ceiling and sealed at all interfaces, steam-rated low-voltage downlights with sealed gaskets, a steam-rated extraction unit, a separate condensate drain at the base of the shower, and an in-shower control panel for the Helo HSXS 60 steam generator. A 90-minute steam pressure test held as a contractual hold-point before brassware commissioning: enclosure run at full steam for 90 minutes with an independent surveyor verifying no vapour escape at any junction. Test passed first attempt.
1200×2400mm marble-effect porcelain panels weighing 38kg each are not a tile; they are an architectural panel. Hanging them on walls and ceiling requires suction-cup handling rigs, a levelling-clip tile-fixing system, a substrate prepared to within 1mm flatness across the panel face, and an installer who has fitted the format before. We engaged the specialist large-format porcelain fixer at procurement stage and held the lippage tolerance to 0.5mm at all panel-to-panel junctions in the contract. Book-matching across the bath wall (where two adjacent panels are mirrored to give a continuous grain pattern) was set out in CAD before the panels were cut at the supplier; final lippage measured at handback was 0.3mm worst-case.
Same tanking discipline as the Hale Wet-Room Conversion we delivered earlier in the year, but applied to a different brief. Full Schluter Kerdi sheet tanking system across the floor (lapped over the linear drain and shower waste), and 200mm above every fitting on the walls, with pre-formed Kerdi-Kereck and Kerdi-Kerab corner pieces sealed at every junction. 24-hour flood test commenced Tuesday week 2: shower waste blocked, floor flooded to lip of cove-skirting, left in place; flood test passed Wednesday morning with no measurable level drop. Photo documentation in the homeowners' handover folder.
Chromotherapy lighting is RGB LED, programmable across the colour spectrum, dimmable, integrated with the room's main 5-scene lighting controller. The Hansgrohe Raindance E rainfall head carried the in-shower chromotherapy LED ring; bath-side chromotherapy fittings were recessed into the wall behind the bath. We sat with the homeowners on the Friday morning of week 5 with all chromotherapy and lighting on, scene-programmed five scenes against their stated preferences: Morning bright (clean white at full brightness), Day clean (warm white at 70%), Evening warm (warm amber at 30%), Bath relax (a slow-shifting amber-pink scene synced with the bath chromotherapy), Steam spa (cool blue-green in the steam shower at 20% with a 30-minute timer). Saved to the homeowners' Lutron-style controller; remote control via their existing home app.
The homeowners remained in the property throughout the 5-week build, decanting between their guest ensuite and the family bathroom. Affluent-home site management is a defined discipline: dust-sheet protection from the front door to the work zone, shoe protectors at every threshold, daily clean-down at end of every working day, tools and materials cleared from view at end of every working day, single-point-of-contact site manager on a WhatsApp channel for any ad-hoc question, daily 4pm progress photo update, in-person Friday walkthroughs at end of each week. The homeowners' 16-year-old daughter's room was the closest to the work zone; we observed quiet hours during her exam-revision evenings and made sure she was unaffected.
Luxury master-ensuite spa builds succeed or fail on four things: structural floor design for the cast-iron loading, steam enclosure sealing, large-format porcelain installer specialism, and patient commissioning of chromotherapy and lighting scenes to a couple's preferences. Our approach was built around four working disciplines and one craft discipline.
Structural floor survey at quotation stage, not at site visit one. The two competing quotes treated the cast-iron bath floor loading as a "subject to structural survey, additional work to be confirmed" line. We engaged a structural engineer at quotation stage to walk the existing joist span, calculated the point loading from the Aston Matthews Belmont's specification sheet, and priced the joist doubling and 6mm steel ply inside the contract sum. The competing quote that came in cheaper would have hit the homeowners with a structural variation in week 1; ours did not.
Steam pressure test as a contractual hold-point. The two competing quotes proposed a tanking flood test (the standard wet-room test, which we also did). Steam shower vapour retention is a different problem from water containment: vapour escapes at junctions where water doesn't, and the consequence of escape is condensation in the loft void above the ceiling porcelain over months and years. We held a 90-minute steam pressure test as a contractual hold-point in week 4, with an independent surveyor verifying no vapour escape at any junction. The test caught one minor seal issue at the ceiling-to-wall junction which was remedied the same afternoon and the test re-run successfully.
Specialist large-format porcelain installer engaged at procurement. 1200×2400mm porcelain panels are not a tile. We engaged the specialist installer at procurement stage in week one (the same fixer we used on the heritage joinery interfaces at the Birmingham Colmore Row HQ Fit-Out earlier in the year), confirmed the substrate flatness preparation, the suction-cup handling rig, the levelling-clip system and the book-match CAD set-out for the bath wall before the panels were cut at the supplier. Lippage tolerance held to 0.5mm contractually; measured at handback at 0.3mm worst-case.
Chromotherapy and lighting scenes programmed with the homeowners on site. Chromotherapy and 5-scene dimmable lighting commissioning is the part of a luxury bathroom that nobody plans for properly. We sat with the homeowners on the Friday morning of week 5 for an hour: every scene tuned in real time, saved to the controller, named to their preference, mapped to specific times-of-day on their app. They walked away with an ensuite that felt like theirs, not like a showroom.
Affluent-home site management as a defined discipline. Dust-sheet protection front door to work zone, shoe protectors, daily clean-down at end of every working day, tools cleared from view, single-point-of-contact site manager on a WhatsApp channel, daily 4pm progress photo, Friday walkthroughs, quiet hours observed for the homeowners' teenage daughter's exam revision. The homeowners told us at handback that the four-week mark had felt like the third week because the site had stayed clean throughout.
Twenty-five working days from key handover to first soak. A structurally-led mobilisation, a tanking-and-pressure-test discipline, a large-format porcelain workstream sequenced as a continuous specialist install, and a Friday evening when the homeowners had their first soak in the new bath at 6.30pm.
Site mobilisation Monday morning with dust-sheet protection running from the front door to the master ensuite, shoe protectors at the threshold, single-point-of-contact site manager introduced to the homeowners in person at 8.30am. Strip-out of the existing tired 1990s ensuite: corner shower, bath, basin, WC, dropped suspended ceiling, dated ceramic tile. Existing floor cut back to the joists and inspected jointly with the structural engineer Tuesday afternoon. Joist doubling installed Wednesday on the two joists immediately below the cast-iron bath position; 6mm steel ply spread plate fixed across three joists Thursday. New OSB structural subfloor laid Friday. 18mm plywood backer board fixed to studs at every brassware position. Underfloor heating mat positioned ready for week 2 install.
First-fix electrical: lighting circuits zoned for 5-scene control, chromotherapy LED cabling to shower head and bath positions, steam-rated low-voltage downlight cabling, USB-C wiring to vanity drawer, mirror-light cabling. First-fix plumbing: hot and cold to bath position with floor-mounted bath spout, hot and cold to vanity (with in-line TMV3 valve at basin), Hansgrohe iBox concealed thermostatic valve roughed in for shower, four body jet supply pipework, steam generator condensate drain. Schluter Kerdi sheet tanking installed across floor and walls 200mm above every fitting. 24-hour flood test commenced Tuesday morning; passed Wednesday morning with no measurable level drop. Photo documentation completed.
Electric underfloor heating mat fixed to the tanked floor, energised and resistance-tested. Self-levelling compound poured over the heating mat to give a 1mm-flat substrate ready for the porcelain floor in week 4. Specialist large-format porcelain installer mobilised Tuesday for the wall panels: 1200×2400mm Calacatta-look panels lifted on suction-cup rigs, set on a levelling-clip system with continuous adhesive bedding, lippage tolerance held to 0.5mm at every panel-to-panel junction. Book-match across the bath wall set out from the CAD drawing prepared in week 1; the two book-matched panels installed mid-week with the homeowners present to verify the grain alignment.
Ceiling porcelain installed in the steam shower zone and across the rest of the ensuite ceiling, sealed at all interfaces with the wall panels. Steam shower glass enclosure installed Wednesday: full-height frameless 10mm toughened glass with silicone-sealed junctions at head, jambs, threshold and ceiling. 90-minute steam pressure test commenced Thursday morning with independent surveyor present; one minor seal issue at the ceiling-to-wall junction caught and remedied within the hour, test re-run successfully Thursday afternoon. Pressure-test certification issued. Cast-iron Aston Matthews Belmont bath delivered and lifted into position Friday by 4-person team; ball-and-claw feet attached, bath set on the new structural floor; bath filler and floor-mounted spout commissioned and pressure-tested.
Bespoke walnut-top double-basin vanity delivered Monday and installed Tuesday: Catalano under-mounted basins, soft-close drawers, demisting LED-edge mirrors fitted Tuesday afternoon. Hansgrohe AXOR Citterio brassware fitted across all positions: thermostatic shower valve commissioned and temperature-tested, basin mixers commissioned, bath filler tested. Helo HSXS 60 steam generator commissioned with a half-hour live-steam test through the in-shower control panel. Recessed niche LED commissioned. Vogue UK heated towel rail connected to the wet heating system. Lutron-style 5-scene lighting controller programmed Friday morning with the homeowners on site for an hour: Morning bright, Day clean, Evening warm, Bath relax, Steam spa scenes saved against their preferences. Underfloor heating commissioned at 24°C. Final snag round Thursday; 11 minor items closed by Friday lunchtime. Builders clean Friday afternoon. PC certificate issued Friday afternoon. Cast-iron bath filled with hot water at 4pm; first soak Friday evening at 6.30pm.
The technical detail behind a 12m² luxury master-ensuite spa bathroom built to a homeowner couple's hotel-quality references with the structural, steam-sealing and large-format-porcelain disciplines that those references demand.
Aston Matthews Belmont 1.7m cast-iron double-ended bath on traditional ball-and-claw feet in polished chrome, 130kg empty, 380kg full of water with bather. Floor-mounted bath spout with chrome cross-handles, freestanding bath filler. Internal surface re-enamelled to manufacturer standard.
Structural floor survey commissioned at quotation stage. Joist doubling on the two existing 195mm joists immediately below the bath position; 6mm steel ply spread plate fixed across three joists to distribute the 380kg point load. New OSB structural subfloor over the reinforced joists. Verified by structural engineer at sign-off.
Full Schluter Kerdi sheet tanking system across floor (lapped over linear drain and shower waste) and walls 200mm above every fitting. Pre-formed Kerdi-Kereck and Kerdi-Kerab corner pieces at every junction. 24-hour flood test held as contractual hold-point; passed first time with no measurable level drop. Photo documentation in handover folder.
1m×1m steam shower with full-height frameless 10mm toughened glass enclosure, silicone-sealed at all junctions including ceiling. Helo HSXS 60 steam generator in boxing behind the shower with in-shower programmable control panel. Steam-rated extraction. Separate condensate drain. 90-minute steam pressure test held as contractual hold-point; passed certified.
Hansgrohe Raindance E ceiling-mounted rainfall shower head with integrated chromotherapy LED ring. Four wall-mounted body jets fed from Hansgrohe iBox concealed thermostatic valve with separate diverter for each jet pair. Hand-held shower on slider rail. Thermostatic valve commissioned and temperature-tested. Body-jet flow balanced to manufacturer's spec.
1200×2400mm Calacatta-look marble-effect porcelain panels to walls and ceiling from a single batch range. Specialist installer engaged at procurement stage. Substrate prepared to 1mm flatness; suction-cup handling rigs and levelling-clip system used throughout. Lippage tolerance held to 0.5mm contractually; measured at handback at 0.3mm worst-case.
Two adjacent 1200×2400mm porcelain panels mirrored to give continuous grain pattern across the wall behind the bath. Set out in CAD before panels cut at supplier. Installed mid-week 3 with the homeowners present to verify grain alignment. Single-batch sourcing confirmed at order to ensure tone consistency.
Electric underfloor heating mat across the entire ensuite floor (excluding the cast-iron bath footprint and the steam shower drain zone). Resistance-tested before self-levelling compound poured over. Own thermostat zone integrated into the home's existing heating-controller setup; programmable from the homeowners' phone app. Commissioned at 24°C.
Hansgrohe Raindance E head with integrated chromotherapy LED ring in shower zone. Recessed chromotherapy fittings in the wall behind the bath. Programmable 7-colour RGB, dimmable, scene-integrated with the main 5-scene lighting controller. Bath relax and Steam spa scenes saved at handback against the homeowners' specific preferences.
Polished chrome throughout: thermostatic shower valve plus separate diverters, basin mixers (one per basin), bath filler and floor-mounted bath spout, matched chrome accessories (heated towel rail valves, robe hooks, tissue holder). Single-supplier brassware ensures finish and tone consistency across the room.
1.6m bespoke walnut-top double-basin vanity unit with two under-mounted Catalano basins, push-open soft-close drawer banks each side, concealed wiring for chromotherapy controls in left drawer, integrated USB-C charging in right drawer, demisting LED-edge mirrors above each basin. Hand-finished walnut top oiled to natural matt.
Lutron-style 5-scene dimmable lighting controller integrating ceiling downlights, niche LEDs, vanity lights, mirror lights and chromotherapy zones. Five scenes programmed with the homeowners on site Friday morning week 5: Morning bright, Day clean, Evening warm, Bath relax, Steam spa. Remote control via the homeowners' existing home app.
A 12m² master-ensuite spa bathroom suite in a renovated detached home in Wilmslow delivered against a 5-week fixed-price contract with no variation orders, the structural floor reinforcement for the cast-iron bath signed off by the structural engineer in week 1, the Schluter Kerdi tanking system passing its 24-hour flood test on first attempt, the 90-minute steam pressure test passing on re-run after a single ceiling-to-wall seal issue was caught and fixed within the hour, the large-format 1200×2400mm porcelain installed by a specialist fixer to a 0.3mm worst-case lippage against a 0.5mm contractual target, the bath-wall book-match verified by the homeowners themselves on installation, all five Lutron-style lighting scenes programmed with the homeowners on site Friday morning of handback, and the cast-iron bath filled with hot water at 4pm Friday for a 6.30pm first soak.
The Hale Wet-Room Conversion we delivered earlier in the year was a 3-week accessibility-led adaptation in an older couple's home where the contracted milestone was the Trafford Council Occupational Therapist signing off the works at 10.40am on the Friday morning of handback; this Wilmslow Spa Bathroom Suite was the same bathroom-category methodology applied to a luxury master ensuite five weeks long where the contracted milestone was the homeowners' first soak in the cast-iron bath at 6.30pm on the Friday evening of handback. Different chapter of life, different brief, different products, same disciplines underneath: tanking flood-tested as a contractual hold-point, structural backing where the loads matter, specialist installers engaged at procurement stage, commissioning patience for the controls.
We had just finished a substantial whole-house renovation of our home in Wilmslow when we turned our attention to our tired master ensuite. We knew exactly what we wanted from the bathrooms we had used at a couple of UK boutique hotels we keep going back to: a freestanding cast-iron bath, a steam shower with a rainfall head and body jets, marble-effect porcelain to ceiling, the kind of lighting that turns a bathroom into somewhere you actually want to spend forty minutes at the end of the day. We tendered three contractors. Building Group came in second on price by about eighteen hundred pounds. We chose them because their quotation was the only one to include the structural floor survey for the cast-iron bath inside the contract sum rather than as a "subject to survey" provisional, the only one to propose a steam-enclosure pressure test as a contractual hold-point in addition to the standard tanking flood test (and on the day, the test caught a single seal issue at the ceiling-wall junction that the others would have missed), and the only one to engage the specialist large-format porcelain installer at procurement rather than at handover. The book-matched panels behind the bath were laid out in CAD before they were cut at the supplier; the panels arrived numbered and the grain alignment is genuinely seamless. The team kept the dust out of the rest of the house, daily four o'clock photo updates kept us in the loop, and on the Friday morning we sat with the project manager for an hour while he programmed the five lighting scenes with us until we had them right. The cast-iron bath was filled at four o'clock that afternoon; my wife was in it at half past six. We have already recommended Building Group to two friends in the area.
If you've been planning a master-ensuite rebuild around a freestanding bath you have already chosen, a steam shower you have used at a hotel and want at home, or a complete spa-quality bathroom suite for your renovated property, we'll come out for a free home visit, walk the existing space with you and any interior designer involved, and put a fixed-price quotation on your desk — with the structural floor survey, the tanking and steam pressure tests, the specialist large-format porcelain installer, the brassware specification, the chromotherapy and lighting commissioning and the kind of clean site management your home deserves all costed in.
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