Home Office Conversion Guide for London Homes

A GARDEN ROOM IS THE MOST POPULAR HOME OFFICE SOLUTION IN LONDON WHERE REAR GARDEN SPACE ALLOWS. A WELL-SPECIFIED GARDEN ROOM PROVIDES COMPLETE SEPARATION FROM THE MAIN HOUSE (CRITICAL FOR VIDEO CALL ACOUSTICS AND FOCUS), NO DISRUPTION TO THE EXISTING HOUSE DURING CONSTRUCTION, AND A RAPID BUILD PROGRAMME (6-12 WEEKS FROM GROUNDWORKS TO HANDOVER). PLANNING RULES FOR GARDEN BUILDINGS (CLASS E OF THE GPDO 2015): OUTBUILDINGS IN THE REAR GARDEN ARE PERMITTED DEVELOPMENT PROVIDED: (1) MAXIMUM EAVES HEIGHT 2.5M; MAXIMUM OVERALL HEIGHT 4.0M (DUAL PITCH) OR 3.0M (ANY OTHER ROOF TYPE) — THIS IS THE KEY PD CONSTRAINT AS MOST QUALITY GARDEN ROOMS WITH GOOD CEILING HEIGHT APPROACH 3.0M TO RIDGE; (2) OUTBUILDING DOES NOT COVER MORE THAN 50% OF THE TOTAL GARDEN AREA WHEN COMBINED WITH ALL OTHER OUTBUILDINGS; (3) OUTBUILDING IS NOT FORWARD OF THE PRINCIPAL ELEVATION; (4) WITHIN CONSERVATION AREAS: OUTBUILDINGS ARE NOT PERMITTED DEVELOPMENT IN THE SIDE GARDEN OR FRONT GARDEN (REAR GARDEN STILL APPLIES). FOR HABITABLE GARDEN OFFICES (INSULATED TO BUILDING REGULATIONS STANDARD WITH PLUMBING OR ELECTRICAL INSTALLATION AS PRIMARY WORK AREA): BUILDING REGULATIONS PART L (ENERGY EFFICIENCY — NEW DWELLINGS) DOES NOT APPLY TO NON-HABITABLE OUTBUILDINGS, BUT DOES APPLY IF THE GARDEN ROOM IS DESIGNED FOR REGULAR OCCUPATION (WORK). AN ELECTRICAL INSTALLATION (CIRCUITS, CONSUMER UNIT) IN A GARDEN ROOM REQUIRES PART P NOTIFICATION. RECOMMENDED SPECIFICATION: TIMBER FRAME SIP PANEL CONSTRUCTION (STRUCTURAL INSULATED PANEL, 100-140MM THICK, U-VALUE 0.18-0.22 W/M2K); WARM FLAT ROOF (EPDM OR SARNAFIL, 150MM PIR); TOUGHENED DOUBLE GLAZED TIMBER OR ALUMINIUM WINDOWS AND DOORS; ELECTRIC UNDERFLOOR HEATING OR ELECTRIC PANEL HEATERS ON A DEDICATED CIRCUIT.

GARAGE CONVERSION IS ONE OF THE HIGHEST-VALUE-FOR-MONEY HOME IMPROVEMENTS IN LONDON. AN INTEGRAL OR ATTACHED GARAGE CONVERTED TO A HOME OFFICE ADDS USABLE SPACE TO THE HOUSE WITHOUT REQUIRING EXTERNAL EXTENSION OR GARDEN LOSS. THE TOTAL FLOOR AREA OF A STANDARD LONDON SINGLE GARAGE (5.5M X 3.0M = 16.5M2) IS ADEQUATE FOR A PRIVATE OFFICE FOR 1-2 PEOPLE WITH STORAGE AND MEETING AREA. PLANNING: GARAGE CONVERSION (CHANGING USE FROM GARAGE TO HABITABLE ROOM) DOES NOT REQUIRE PLANNING PERMISSION AS PERMITTED DEVELOPMENT PROVIDED THE EXTERNAL APPEARANCE OF THE BUILDING DOES NOT MATERIALLY CHANGE (I.E. THE GARAGE DOOR OPENING IS FILLED IN WITHOUT CHANGING THE OVERALL BUILDING ENVELOPE). IN CONSERVATION AREAS: THE INFILL MATERIAL AND APPEARANCE MUST MATCH THE EXISTING BUILDING CHARACTER — BRICK INFILL MATCHING THE MAIN HOUSE IS TYPICALLY REQUIRED. BUILDING REGULATIONS: GARAGE CONVERSION TO HABITABLE ROOM ALWAYS REQUIRES BUILDING REGULATIONS APPROVAL (FULL PLANS OR BUILDING NOTICE ROUTE). THE KEY PARTS THAT APPLY: PART A (STRUCTURAL) — FLOOR SLAB ASSESSMENT (OFTEN ONLY 100MM UNREINFORCED CONCRETE — MAY NEED TO BE UPGRADED IF HEAVY FLOOR LOADS OR UNDERFLOOR HEATING INSTALLED); PART C (SITE PREPARATION — DPC CONTINUITY BETWEEN GARAGE AND HOUSE); PART F (VENTILATION — BACKGROUND VENTILATION REQUIRED); PART L (THERMAL ENVELOPE — INSULATION OF ALL WALLS, FLOOR, AND ROOF/CEILING TO MEET U-VALUE TARGETS). TECHNICAL SPECIFICATION: FLOOR: 100MM PIR (KINGSPAN KOOLTHERM K5 OR CELOTEX GA4000) OVER EXISTING SLAB + 65MM HANSON CEMFLOOR LIQUID SCREED + WARMUP ELECTRIC UFH MAT. WALLS: 100MM MINERAL WOOL (ROCKWOOL SAFE GUARD) BETWEEN STEEL STUD FRAME INTERNALLY. CEILING: 150MM KNAUF LOFT ROLL 44 BETWEEN JOISTS + DOUBLE LAYER 12.5MM PLASTERBOARD FOR ACOUSTIC PERFORMANCE.

A LOFT CONVERSION THAT CREATES A DEDICATED HOME OFFICE PROVIDES THE BENEFIT OF PHYSICAL SEPARATION (TOP FLOOR — AWAY FROM MAIN HOUSE NOISE), ACCESS TO NATURAL LIGHT FROM ABOVE (ROOF WINDOWS), AND NO GARDEN LOSS. THE LOFT OFFICE IS IDEAL WHERE THE GROUND AND FIRST FLOORS ARE HEAVILY USED FAMILY SPACE AND A QUIET RETREAT IS NEEDED. THE CONVERSION CREATES A NEW STAIRCASE (USUALLY REPLACING AN AIRING CUPBOARD OR LANDING AREA ON THE FIRST FLOOR — THE SINGLE MOST IMPACTFUL DESIGN DECISION), A STUD-WORK FLOOR AT THE EXISTING CEILING LEVEL, AND STRUCTURAL FLOOR JOISTS ABOVE. BUILDING REGULATIONS: SAME AS A HABITABLE LOFT CONVERSION — PART A (STRUCTURAL FLOORS, RAFTERS, STEELWORK), PART B (FIRE SAFETY — THIRD FLOOR REQUIRES FIRE-SPRINKLER CONSIDERATION IN SOME CONFIGURATIONS), PART F (VENTILATION), PART L (INSULATION). INTERNET CONNECTIVITY: A DEDICATED CAT6 OR CAT6A RJ45 SOCKET RUN FROM THE MAIN ROUTER LOCATION (USUALLY GROUND FLOOR) IS STRONGLY RECOMMENDED FOR A LOFT OFFICE — WI-FI SIGNAL AT TOP-FLOOR LEVEL IN A LONDON TERRACE IS OFTEN DEGRADED BY INTERVENING FLOORS AND MASONRY. A SINGLE-PIECE CAT6 RUN (NO JOINS) FROM ROUTER TO LOFT OFFICE, TERMINATED IN A LEGRAND MOSAIC KEYSTONE JACK SOCKET, COSTS £150-£300 INCLUDING LABOUR AND IS FAR MORE RELIABLE THAN A WI-FI EXTENDER OR POWERLINE ADAPTER. ACOUSTIC DESIGN FOR A LOFT OFFICE: TIMBER FLOOR JOISTS WITH 150MM ROCKWOOL SAFE GUARD BETWEEN JOISTS + 25MM REGUPOL ACOUSTIC MAT (IMPACT SOUND DEADENER) + 22MM TONGUE-AND-GROOVE CHIPBOARD FLOORING GIVES APPROXIMATELY 48DB IMPACT SOUND REDUCTION — ADEQUATE FOR A HOME OFFICE OVER A BEDROOM.

A REAR OR SIDE-RETURN EXTENSION SPECIFICALLY DESIGNED AS A HOME OFFICE IS CHOSEN BY LONDON HOMEOWNERS WHO WANT: LEVEL ACCESS FROM THE MAIN HOUSE WITH NO STAIRCASE; WHEELCHAIR ACCESSIBLE WORKSPACE; LARGE SOUTH-FACING GLAZING (POSSIBLE ON A REAR EXTENSION IF THE GARDEN FACES SOUTH); OR COMBINED KITCHEN-EXTENSION WITH DEDICATED OFFICE ZONE. THE DESIGN CHALLENGE IS ACOUSTIC SEPARATION FROM THE MAIN HOUSE — AN OPEN-PLAN EXTENSION ADJACENT TO THE KITCHEN WILL NOT PROVIDE THE QUIET ENVIRONMENT A HOME OFFICE NEEDS. THE SOLUTION IS A PARTITION WALL BETWEEN THE OPEN-PLAN KITCHEN/DINER AND THE OFFICE ZONE, WITH A SOLID-CORE FD30 DOOR BETWEEN THEM. ACOUSTIC PARTITION SPECIFICATION: 2X75MM METAL STUD FRAME (STAGGERED TRACK SYSTEM WITH NO DIRECT STUD CONTACT BETWEEN THE TWO FRAMES — "DE-COUPLED" CONSTRUCTION) WITH 150MM ROCKWOOL RWA45 BATTS BETWEEN STUDS + 2 LAYERS 15MM BRITISH GYPSUM GLASROC H ON EACH FACE — GIVES APPROXIMATELY 48-52DB SOUND REDUCTION BETWEEN OFFICE AND KITCHEN. THIS IS THE CORRECT SPECIFICATION FOR AN OFFICE THAT REQUIRES PRIVATE PHONE/VIDEO CALL CAPABILITY. INTERNET AND MEDIA OUTLETS: PLAN THE CABLE INFRASTRUCTURE BEFORE WALLS ARE CLOSED. MINIMUM RECOMMENDATION: 2X CAT6A SOCKETS (DATA), 1X HDMI RECESSED WALL PLATE (FOR SCREEN), 1X USB-A+C CHARGING STATION, DOUBLE SOCKETS AT DESK HEIGHT (EVERY 1.2M OF DESK RUN) — ALL SPECIFIED DURING FIRST FIX ELECTRICAL STAGE.

BEYOND STRUCTURE AND PLANNING, THE DESIGN DETAILS THAT MAKE A HOME OFFICE WORK FOR LONDON PROFESSIONALS: (1) NATURAL LIGHT — NORTH-FACING WINDOWS PROVIDE EVEN, GLARE-FREE LIGHT IDEAL FOR SCREEN WORK; SOUTH-FACING WINDOWS REQUIRE SOLAR CONTROL GLASS (PILKINGTON OPTIFLOAT OR ST GOBAIN COOL-LITE SKN 176 WITH G=0.42) AND EXTERNAL BLINDS (LUXAFLEX EXTERNAL VENETIAN BLIND OR MARKILUX 820 ROLLER BLIND) TO PREVENT OVERHEATING AND SCREEN GLARE. (2) ACOUSTIC TREATMENT — HARD PARALLEL SURFACES (GLASS WINDOWS + TILED FLOOR) CAUSE REVERBERATION THAT MAKES VIDEO CALLS ECHO. A COMBINATION OF ACOUSTIC PANELS (SILENT GLISS OMEGA ACOUSTIC PANEL OR ARMSTRONG SOUNDSOAK GLASS WOOL TILES — 75MM THICK FOR HIGH ABSORPTION AT 250HZ-4KHZ) AND SOFT FURNISHINGS (RUG, SOFA/CHAIR, CURTAINS) BRINGS MID-FREQUENCY REVERBERATION TIME (RT60) TO UNDER 0.4 SECONDS — THE TARGET FOR INTELLIGIBLE SPEECH IN A HOME OFFICE. (3) THERMAL COMFORT — ELECTRIC UNDERFLOOR HEATING (WARMUP STICKY MAT, THERMOSTATIC CONTROL VIA HEATMISER NEOSTAT) IS IDEAL FOR AN OFFICE AS IT PROVIDES EVEN BACKGROUND HEAT WITHOUT HOT SPOTS FROM RADIATORS. SUMMER COOLING IN LONDON OFFICES IS INCREASINGLY NEEDED — A MITSUBISHI MSZ-AP SERIES MINI-SPLIT SYSTEM (2.5KW INVERTER, WALL-MOUNTED) PROVIDES BOTH COOLING AND SUPPLEMENTARY HEATING AND COSTS £1,200-£1,800 SUPPLY AND FIT (NO GAS CONNECTION REQUIRED). (4) ERGONOMIC DESIGN — MINIMUM 1.6M DESK DEPTH FOR A STANDING DESK (FLEXISPOT E7 ELECTRIC HEIGHT-ADJUSTABLE, 70-119CM HEIGHT RANGE); MONITOR ARMS (ERGOTRON LX) ALLOWING SCREEN POSITIONING AT EYE LEVEL; OFFICE CHAIR (HERMAN MILLER EMBODY, STEELCASE LEAP V2, OR SECRETLAB TITAN EVO FOR LONGER WORKING DAYS).

GARDEN ROOM COSTS: BUDGET KIT-BUILD INSULATED GARDEN OFFICE (3M X 3M, SIP PANELS, ELECTRIC HEATING, BASIC ELECTRICS): £8,000-£14,000 SUPPLY AND FIT. MID-SPEC BESPOKE GARDEN STUDIO (4M X 3M, WARM FLAT ROOF, ALUMINIUM BI-FOLD DOOR, ELECTRIC UFH, PART P ELECTRICS): £18,000-£28,000. PREMIUM GARDEN OFFICE (5M X 4M, GREEN ROOF, TRIPLE GLAZED, MVHR, FULL AV + NETWORK): £30,000-£50,000. GARAGE CONVERSION COSTS (SINGLE GARAGE TO HOME OFFICE): BASIC (INSULATION, ELECTRICS, DECORATING): £8,000-£14,000. MID-SPEC (NEW FLOOR SCREED + UFH, FULL REFIT, ACOUSTIC CEILING): £14,000-£22,000. LOFT CONVERSION TO HOME OFFICE (WITH STAIRCASE): £25,000-£45,000 DEPENDING ON TYPE (VELUX ONLY VS DORMER). REAR EXTENSION HOME OFFICE (SINGLE-STOREY, 12M2, STRUCTURAL OPENING, GLASS DOOR TO GARDEN): £35,000-£60,000 (FULL BUILD, INCLUDED IN COMBINED KITCHEN-EXTENSION PROJECT). NOTE: ALL OPTIONS REQUIRE BROADBAND/NETWORK INFRASTRUCTURE — BUDGET £500-£1,500 FOR CAT6 CABLING, PATCH PANELS, AND NETWORK SOCKETS WHERE NOT INCLUDED IN MAIN BUILD PACKAGE.