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Extensions and Garden Rooms2 min read

Conservatory and Garden Room Guide for London Homes in 2025: Most Specified Conservatories, Garden Rooms, Roof Lanterns, and London Conservatory Costs

CONSERVATORIES AND GARDEN ROOMS ARE ONE OF THE FASTEST-GROWING SEGMENTS OF LONDON RESIDENTIAL RENOVATION IN 2025 — DRIVEN BY THE INCREASED DEMAND FOR HOME WORKING SPACE, INCREASED LIVING SPACE, AND SEAMLESS INDOOR-OUTDOOR CONNECTION FOLLOWING THE LONDON RESIDENTIAL RENOVATION BOOM OF 2021-2024. THE DISTINCTION BETWEEN A CONSERVATORY AND A GARDEN ROOM IN LONDON RESIDENTIAL RENOVATION IN 2025 IS PRIMARILY A PLANNING AND BUILDING REGULATIONS DISTINCTION: A CONSERVATORY (AS DEFINED BY APPROVED DOCUMENT L IN ENGLAND) IS A SINGLE-STOREY EXTENSION SEPARATED FROM THE MAIN HOUSE BY WALLS/DOORS/WINDOWS, WITH MORE THAN 50% OF ITS ROOF AREA AND MORE THAN 50% OF ITS WALL AREA BEING TRANSLUCENT — AND A CONSERVATORY MEETING THESE CRITERIA IS EXEMPT FROM THE THERMAL PERFORMANCE REQUIREMENTS OF PART L OF THE BUILDING REGULATIONS — WHILE A GARDEN ROOM THAT DOES NOT MEET THESE CRITERIA IS CLASSIFIED AS A HABITABLE EXTENSION AND MUST MEET FULL PART L THERMAL PERFORMANCE REQUIREMENTS. THE THREE MOST COMMON CONSERVATORY AND GARDEN ROOM PROJECTS IN LONDON RESIDENTIAL RENOVATION IN 2025 ARE: CONSERVATORY ROOF REPLACEMENT (THE MOST COMMON CONSERVATORY PROJECT IN LONDON RESIDENTIAL RENOVATION IN 2025 — WHERE THE ORIGINAL POLYCARBONATE ROOF OF AN EXISTING CONSERVATORY IS BEING REPLACED WITH A SOLID TILED ROOF OR AN UPGRADED GLAZED SYSTEM TO IMPROVE THERMAL PERFORMANCE AND USABILITY YEAR-ROUND); NEW ALUMINIUM GARDEN ROOM (THE SECOND MOST COMMON PROJECT IN LONDON RESIDENTIAL RENOVATION IN 2025 — WHERE A NEW FULLY GLAZED ALUMINIUM FRAMED GARDEN ROOM IS BEING BUILT AT THE BOTTOM OF OR ADJACENT TO THE REAR GARDEN AS A SEPARATE STRUCTURE); ROOF LANTERN INSTALLATION (THE THIRD MOST COMMON CONSERVATORY-RELATED PROJECT IN LONDON RESIDENTIAL RENOVATION IN 2025 — WHERE A ROOF LANTERN IS INSTALLED ON A FLAT ROOF REAR EXTENSION TO BRING NATURAL LIGHT INTO THE EXTENSION INTERIOR).

Key Takeaways

  • ✓Most specified conservatory and garden room products London residential renovation 2025: CONSERVATORY ROOF REPLACEMENT: Ultraframe Loggia/Livin Room solid tiled roof replacement system (most specified conservatory roof replacement system London residential renovation 2025 — converts unusable hot-in-summer/cold-in-winter polycarbonate conservatory into year-round usable room); Pilkington Activ Blue self-cleaning solar control low-E glass conservatory roof (most specified glass conservatory roof replacement London residential renovation 2025 where client retains glass roof — blue solar control reduces solar gain in summer most cited conservatory usability problem London residential renovation 2025); ALUMINIUM GARDEN ROOMS: Smart Architectural Aluminium Alitherm 600 thermally broken curtain wall system triple glazed Pilkington Optitherm S3 Plus low-E (most specified aluminium framing system fully glazed freestanding garden room London residential renovation 2025 — triple glazed most specified glazing specification garden room home office+year-round habitable space London residential renovation 2025); Apropos Tectonica bespoke glazed garden room (most specified bespoke glazed garden room specialist London residential renovation 2025 — larger budget projects requiring fully bespoke architectural glazed structure); ROOF LANTERNS: Korniche Roof Lantern thermally broken aluminium frame (most specified roof lantern London residential renovation 2025 — 1500mm×1500mm most installed size single flat roof kitchen extension London residential renovation 2025 — Pilkington Optitherm S3 Plus low-E triple glazed most specified glazing for Korniche roof lantern London residential renovation 2025 — triple glazing reduces heat loss through roof lantern most cited thermal weak point flat roof rear extension London residential renovation 2025).
  • ✓Planning, Part L, and London conservatory and garden room costs 2025: PLANNING: permitted development most cited planning route conservatory+garden room London residential renovation 2025 — criteria: single storey/maximum height 4m/maximum eaves height 3m/not beyond side elevation/not more than half area of land around original house/not fronting highway; maximum rear extension depth 3m attached house (possible extension to 6m prior approval notification); PART L: conservatory exempt from Part L thermal performance requirements if: more than 50% roof translucent+more than 50% external wall translucent+separated from house by doors/windows/walls+not heated by main heating system (most cited conservatory Part L exemption criteria London residential renovation 2025); garden room that does not meet these criteria classified as habitable extension must meet full Part L thermal performance requirements London residential renovation 2025; COSTS LONDON 2025: Ultraframe Loggia tiled roof replacement 15m² existing uPVC conservatory including structural ridge+new solid roof+tile: £8,000-£18,000; fully glazed aluminium garden room 15m² Smart Alitherm 600 triple glazed including foundations+groundworks: £25,000-£50,000; Apropos Tectonica bespoke glazed garden room 20m²+: £40,000-£100,000+; Korniche roof lantern 1500mm×1500mm supply+fit triple glazed Pilkington Optitherm S3 Plus: £2,000-£4,000; Korniche roof lantern 2000mm×1000mm supply+fit triple glazed: £2,500-£4,500.

Contents

  1. 1. Most specified conservatory roof systems, aluminium garden rooms, and roof lanterns for London residential renovation in 2025
  2. 2. Planning and building regulations, Part L, and London conservatory and garden room costs in 2025
  3. 3. Frequently Asked Questions

Most specified conservatory roof systems, aluminium garden rooms, and roof lanterns for London residential renovation in 2025

Most specified conservatory roof replacement systems, aluminium garden rooms, bespoke glazed structures, and roof lanterns for London residential renovation in 2025: CONSERVATORY ROOF REPLACEMENT SYSTEMS — MOST SPECIFIED IN LONDON RESIDENTIAL RENOVATION IN 2025: MOST SPECIFIED CONSERVATORY ROOF REPLACEMENT SYSTEM IN LONDON RESIDENTIAL RENOVATION IN 2025: ULTRAFRAME LOGGIA / LIVIN ROOM SOLID TILED ROOF SYSTEM (THE MOST SPECIFIED CONSERVATORY ROOF REPLACEMENT SYSTEM IN LONDON RESIDENTIAL RENOVATION IN 2025 — ULTRAFRAME LOGGIA (FOR AN ORANGERY-STYLE TILED ROOF OVER AN EXISTING UPVC CONSERVATORY FRAME) / ULTRAFRAME LIVIN ROOM (THE MOST INSTALLED ULTRAFRAME PRODUCT FOR A COMPLETE REPLACEMENT INCLUDING SURROUND WALLS AND LANTERN ROOF) — MOST SPECIFIED BECAUSE THE ULTRAFRAME SOLID TILED ROOF SYSTEM CONVERTS AN UNUSABLE HOT-IN-SUMMER/COLD-IN-WINTER POLYCARBONATE CONSERVATORY INTO A YEAR-ROUND USABLE ROOM); MOST SPECIFIED GLAZED CONSERVATORY ROOF REPLACEMENT IN LONDON RESIDENTIAL RENOVATION IN 2025: CELSIUS SMART SELF-CLEANING GLASS CONSERVATORY ROOF REPLACEMENT (THE MOST SPECIFIED GLASS CONSERVATORY ROOF REPLACEMENT SYSTEM IN LONDON RESIDENTIAL RENOVATION IN 2025 WHERE THE CLIENT WISHES TO RETAIN A GLASS ROOF RATHER THAN CONVERTING TO A SOLID TILED ROOF — MOST SPECIFIED GLASS TYPE IN LONDON RESIDENTIAL RENOVATION IN 2025 FOR A CONSERVATORY ROOF: PILKINGTON ACTIV BLUE SELF-CLEANING SOLAR CONTROL LOW-E GLASS (THE MOST SPECIFIED GLASS IN LONDON RESIDENTIAL RENOVATION IN 2025 FOR A CONSERVATORY ROOF BECAUSE THE BLUE SOLAR CONTROL REDUCES SOLAR GAIN IN SUMMER — THE MOST CITED CONSERVATORY USABILITY PROBLEM IN LONDON RESIDENTIAL RENOVATION IN 2025 — AND THE SELF-CLEANING COATING REDUCES MAINTENANCE)); ALUMINIUM GARDEN ROOMS — MOST SPECIFIED IN LONDON RESIDENTIAL RENOVATION IN 2025: MOST SPECIFIED ALUMINIUM GARDEN ROOM FRAMING SYSTEM IN LONDON RESIDENTIAL RENOVATION IN 2025: SMART ARCHITECTURAL ALUMINIUM ALITHERM 600 THERMALLY BROKEN ALUMINIUM CURTAIN WALL SYSTEM (THE MOST SPECIFIED ALUMINIUM FRAMING SYSTEM IN LONDON RESIDENTIAL RENOVATION IN 2025 FOR A FULLY GLAZED FREESTANDING ALUMINIUM GARDEN ROOM — SMART ALITHERM 600 — THERMALLY BROKEN ALUMINIUM MULLION AND TRANSOM CURTAIN WALL SYSTEM — MOST SPECIFIED WITH TRIPLE GLAZED PILKINGTON OPTITHERM S3 PLUS LOW-E UNITS FOR A THERMALLY EFFICIENT FULLY HABITABLE GARDEN ROOM (THE MOST SPECIFIED GLAZING SPECIFICATION IN LONDON RESIDENTIAL RENOVATION IN 2025 FOR A GARDEN ROOM INTENDED AS A HOME OFFICE OR YEAR-ROUND HABITABLE SPACE)); MOST SPECIFIED BESPOKE GLAZED GARDEN ROOM SPECIALIST IN LONDON RESIDENTIAL RENOVATION IN 2025: APROPOS TECTONICA (THE MOST SPECIFIED BESPOKE GLAZED GARDEN ROOM AND CONTEMPORARY GLASSHOUSE SPECIALIST IN LONDON RESIDENTIAL RENOVATION IN 2025 — APROPOS — MOST SPECIFIED FOR LARGER BUDGET PROJECTS IN LONDON RESIDENTIAL RENOVATION IN 2025 WHERE A FULLY BESPOKE ARCHITECTURAL GLAZED STRUCTURE IS REQUIRED); ROOF LANTERNS — MOST SPECIFIED IN LONDON RESIDENTIAL RENOVATION IN 2025: MOST SPECIFIED ROOF LANTERN IN LONDON RESIDENTIAL RENOVATION IN 2025: KORNICHE ROOF LANTERN BY KORNICHE ALUMINIUM (THE MOST SPECIFIED ROOF LANTERN IN LONDON RESIDENTIAL RENOVATION IN 2025 — KORNICHE ROOF LANTERN — THERMALLY BROKEN ALUMINIUM FRAME — MOST SPECIFIED SIZES IN LONDON RESIDENTIAL RENOVATION IN 2025: 1500MM × 1500MM (THE MOST INSTALLED SIZE FOR A SINGLE FLAT ROOF KITCHEN EXTENSION IN LONDON RESIDENTIAL RENOVATION IN 2025) AND 2000MM × 1000MM (THE SECOND MOST INSTALLED SIZE IN LONDON RESIDENTIAL RENOVATION IN 2025); MOST SPECIFIED GLAZING FOR KORNICHE ROOF LANTERN IN LONDON RESIDENTIAL RENOVATION IN 2025: PILKINGTON OPTITHERM S3 PLUS LOW-E TRIPLE GLAZED UNITS (THE MOST SPECIFIED GLAZING FOR A ROOF LANTERN IN LONDON RESIDENTIAL RENOVATION IN 2025 — MOST SPECIFIED BECAUSE TRIPLE GLAZING REDUCES HEAT LOSS THROUGH THE ROOF LANTERN WHICH IS THE MOST CITED THERMAL WEAK POINT IN A FLAT ROOF REAR EXTENSION IN LONDON RESIDENTIAL RENOVATION IN 2025)).

Planning and building regulations, Part L, and London conservatory and garden room costs in 2025

Planning and building regulations requirements, Part L, and typical London residential conservatory and garden room costs in 2025: PLANNING AND BUILDING REGULATIONS FOR CONSERVATORIES AND GARDEN ROOMS IN LONDON RESIDENTIAL RENOVATION IN 2025: THE MOST CITED PLANNING RULE FOR A CONSERVATORY OR GARDEN ROOM IN LONDON RESIDENTIAL RENOVATION IN 2025 IS PERMITTED DEVELOPMENT — WHERE A CONSERVATORY OR SINGLE-STOREY REAR EXTENSION (INCLUDING A GARDEN ROOM ATTACHED TO THE MAIN HOUSE) CAN BE BUILT WITHOUT PLANNING PERMISSION UNDER PERMITTED DEVELOPMENT RIGHTS PROVIDED IT MEETS THE FOLLOWING CRITERIA (THE MOST CITED PERMITTED DEVELOPMENT REQUIREMENTS IN LONDON RESIDENTIAL RENOVATION IN 2025): SINGLE STOREY; MAXIMUM HEIGHT 4M; MAXIMUM EAVES HEIGHT 3M; DOES NOT EXTEND BEYOND THE SIDE ELEVATION OF THE ORIGINAL HOUSE; DOES NOT TAKE UP MORE THAN HALF THE AREA OF LAND AROUND THE ORIGINAL HOUSE; DOES NOT FRONT THE HIGHWAY; MOST CITED PERMITTED DEVELOPMENT DIMENSION IN LONDON RESIDENTIAL RENOVATION IN 2025 FOR A SINGLE-STOREY REAR EXTENSION: MAXIMUM REAR EXTENSION DEPTH 3M FOR AN ATTACHED HOUSE (WITH POSSIBLE EXTENSION TO 6M USING PRIOR APPROVAL NOTIFICATION — THE MOST CITED PD EXTENSION ROUTE IN LONDON RESIDENTIAL RENOVATION IN 2025 FOR A REAR EXTENSION EXCEEDING 3M DEPTH); BUILDING REGULATIONS PART L FOR CONSERVATORY EXEMPTION IN LONDON RESIDENTIAL RENOVATION IN 2025: A CONSERVATORY IS EXEMPT FROM PART L THERMAL PERFORMANCE REQUIREMENTS IF: MORE THAN 50% OF THE ROOF IS TRANSLUCENT; MORE THAN 50% OF THE EXTERNAL WALL AREA IS TRANSLUCENT; IT IS SEPARATED FROM THE HOUSE BY DOORS, WINDOWS, OR WALLS; THE CONSERVATORY IS NOT HEATED BY THE MAIN HEATING SYSTEM; LONDON RESIDENTIAL CONSERVATORY AND GARDEN ROOM COSTS IN 2025 (SUPPLY+FIT): ULTRAFRAME LOGGIA TILED ROOF REPLACEMENT TO AN EXISTING 15M² UPVC CONSERVATORY INCLUDING STRUCTURAL RIDGE AND NEW SOLID ROOF WITH TILE (LONDON RESIDENTIAL 2025): £8,000-£18,000; FULLY GLAZED ALUMINIUM GARDEN ROOM 15M² SMART ALITHERM 600 CURTAIN WALL SYSTEM TRIPLE GLAZED INCLUDING FOUNDATIONS AND GROUNDWORKS (LONDON RESIDENTIAL 2025): £25,000-£50,000; APROPOS TECTONICA BESPOKE GLAZED GARDEN ROOM 20M²+ (LONDON RESIDENTIAL 2025): £40,000-£100,000+; KORNICHE ROOF LANTERN 1500MM×1500MM SUPPLY+FIT INCLUDING TRIPLE GLAZED PILKINGTON OPTITHERM S3 PLUS LOW-E UNITS (LONDON RESIDENTIAL 2025): £2,000-£4,000; KORNICHE ROOF LANTERN 2000MM×1000MM SUPPLY+FIT TRIPLE GLAZED (LONDON RESIDENTIAL 2025): £2,500-£4,500.

Frequently Asked Questions

What are the most specified conservatory and garden room products for London residential renovation in 2025 and what do they cost?▼
MOST SPECIFIED CONSERVATORY AND GARDEN ROOM PRODUCTS LONDON RESIDENTIAL RENOVATION 2025 AND COSTS: CONSERVATORY ROOF REPLACEMENT: Ultraframe Loggia/Livin Room solid tiled roof replacement system (most specified conservatory roof replacement system London residential renovation 2025 — converts unusable hot-in-summer/cold-in-winter polycarbonate conservatory into year-round usable room most cited reason specifying Ultraframe Loggia/Livin Room London residential renovation 2025); Pilkington Activ Blue self-cleaning solar control low-E glass conservatory roof replacement (most specified glass conservatory roof replacement London residential renovation 2025 where client wishes to retain glass roof — blue solar control reduces solar gain in summer most cited conservatory usability problem London residential renovation 2025 — self-cleaning coating reduces maintenance); ALUMINIUM GARDEN ROOMS: Smart Architectural Aluminium Alitherm 600 thermally broken aluminium curtain wall system mullion+transom triple glazed Pilkington Optitherm S3 Plus low-E (most specified aluminium framing system fully glazed freestanding aluminium garden room London residential renovation 2025 — triple glazed most specified glazing specification London residential renovation 2025 garden room intended as home office+year-round habitable space); Apropos Tectonica bespoke glazed garden room+contemporary glasshouse (most specified bespoke glazed garden room specialist London residential renovation 2025 — most specified for larger budget projects requiring fully bespoke architectural glazed structure London residential renovation 2025); ROOF LANTERNS: Korniche Roof Lantern by Korniche Aluminium thermally broken aluminium frame (most specified roof lantern London residential renovation 2025 — 1500mm×1500mm most installed size single flat roof kitchen extension London residential renovation 2025+2000mm×1000mm second most installed size; Pilkington Optitherm S3 Plus low-E triple glazed most specified glazing for Korniche roof lantern London residential renovation 2025 — triple glazing reduces heat loss through roof lantern most cited thermal weak point flat roof rear extension London residential renovation 2025); PLANNING: permitted development most cited planning route conservatory+garden room London residential renovation 2025 — single storey/maximum height 4m/maximum eaves height 3m/not beyond side elevation/not more than half area of land around original house/not fronting highway most cited PD criteria London residential renovation 2025; maximum rear extension depth 3m attached house (possible extension to 6m prior approval notification most cited PD extension route London residential renovation 2025); PART L: conservatory exempt from Part L thermal performance requirements if more than 50% roof translucent+more than 50% external wall translucent+separated from house by doors/windows/walls+not heated by main heating system (most cited conservatory Part L exemption criteria London residential renovation 2025); COSTS LONDON 2025: Ultraframe Loggia tiled roof replacement 15m² existing uPVC conservatory including structural ridge+new solid roof+tile: £8,000-£18,000; fully glazed aluminium garden room 15m² Smart Alitherm 600 triple glazed including foundations+groundworks: £25,000-£50,000; Apropos Tectonica bespoke glazed garden room 20m²+: £40,000-£100,000+; Korniche roof lantern 1500mm×1500mm supply+fit triple glazed Pilkington Optitherm S3 Plus: £2,000-£4,000; Korniche roof lantern 2000mm×1000mm supply+fit triple glazed: £2,500-£4,500.

Important Note

This guide is for general information only. Building regulations, planning rules, and legal requirements change regularly and vary by local authority. Always seek professional advice specific to your project and location. RCB Design & Build offers free initial consultations — book your free survey.

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