UK Loft Conversion Response turns unused roof space into bedrooms, offices, or bathrooms. We design staircases that fit your landing, calculate roof structural capacity, handle Building Regs Part B fire escape and Part M stair compliance, install Velux windows or dormers—then plaster, wire, and plumb to completion.
Survey week 1. Building Regs approved week 4. Roof work weeks 5-6. Plastered week 7. Complete week 8.
Structural engineers assess existing roof timbers and design steel reinforcement if needed (building up from 2x4" rafters to engineered 9"x2" minimum for habitable rooms). FENSA-registered for roof windows. Building Regs compliant staircases (min 2m headroom, max 42° pitch, min 220mm goings). Fire-rated partitions/doors where required. Work to BS 5268 timber stress grade standards.
From feasibility survey to habitable room sign-off
Simplest/cheapest loft conversion—no external changes (usually Permitted Development, no Planning needed). Requires minimum 2.2m head height at ridge. We reinforce roof structure (upgrade rafters, add collar ties, install purlins), cut Velux openings (3-4 windows typical for bedroom), build staircase, insulate to Part L (270mm between/over rafters, U-value 0.11), plasterboard, wire electrics, fit carpet/flooring. Cost: £22k-32k for standard bedroom. Timeline: 6-8 weeks. Suitable for: terraced/semi/detached with simple gable/hipped roofs. Not suitable for: trussed roofs without extensive reinforcement, head heights under 2.2m at ridge.
Builds box dormer on rear roof slope, increasing usable floor area and head height dramatically. On terraced/semi: usually Permitted Development (max 50m³ volume, not higher than highest part of roof). Cost: £32k-45k for bedroom + ensuite. Timeline: 8-10 weeks. Dormer construction: timber frame built on existing rafters, single-ply membrane roof, tile-hung or rendered sides, windows/doors. Gives 2.3m+ head height across 80% of room (vs 60% with Velux only). Building Regs requirement: fire escape window in bedroom (800mm x 600mm clear opening, max 1,100mm sill height). Party Wall notice required if within 3m of neighbour's property. Structural challenge: dormer weight requires padstones and additional support under rafters.
Converts hipped roof (slopes on all sides) to gable (flat wall on one/both ends), maximizing space. Common on 1930s semis/detached houses. Requires Planning Permission (external alteration, not PD). Cost: £38k-55k. Timeline: 12-14 weeks including Planning. Construction: build new gable wall (blockwork on existing wall plate, rendered/matched to house), rebuild roof structure to gable design, often combined with rear dormer for maximum space gain. Result: bedroom with standing room across full width (vs narrow central strip with hipped roof). Engineering requirement: gable wall must be tied into existing structure, roof load calculations critical. Usually creates 15-20m² extra usable floor area vs Velux-only conversion on same roof.
Most challenging part of loft conversions—stairs must fit existing landing/hallway without losing bedroom space below. Building Regs Part M requirements: max 42° pitch (most lofts need 38-40°), min 220mm goings (tread depth), min 2m headroom throughout, min 600mm clear width, max 16 risers per flight, continuous handrail both sides. Common solutions: extend landing by stealing 600mm from bedroom below, install space-saver/alternating-tread stairs (allowed for loft conversions), spiral stairs (allowed but not ideal for bedroom access—furniture difficult). Cost: £2,500-4,500 depending on complexity. Pre-fabricated stairs typically 10-12 day lead time. We template exact site measurements before ordering (£400 restocking fee if wrong size).
Part B fire regulations critical for loft bedrooms (floor is "second storey" or higher). Requirements: 30-minute fire-rated doors on all rooms opening onto escape route (loft room, first-floor bedrooms), mains-powered interlinked smoke alarms on every floor, protected escape route (hallway must have fire-rated ceiling/walls), fire escape window in loft bedroom (800x600mm clear opening). For three-storey houses (two-storey + loft): hallway/stairwell must be enclosed with fire doors (cannot have open-plan stairs). Costs: fire doors £150-250 each (need 3-5 typically), interlocked alarms £400-600, fire-rated plasterboard/doors add £800-1,200 to build. Inspections: Building Control visits 4-6 times during build, final sign-off checks fire provision thoroughly. No certificate without compliance—affects insurance/mortgage/resale.
Adding WC/shower to loft bedroom. Plumbing challenge: need water pressure (combination boiler typically fine, gravity-fed systems may need pump—£600-900). Drainage: waste pipes must fall 1:40 gradient to reach soil stack, often requires boxing-in/lowering ceilings on floor below. Typical setup: corner shower cubicle (800x800mm), wall-hung WC, wall-mounted basin, electric shower (independent of heating system). Cost: +£6k-9k on top of basic conversion (plumbing £2.5k, fittings £1.5k, tiling £1.2k, electrical £800, drainage £1k-2k). Building Regs: Part G (sanitation), Part P (electrical zones in bathrooms). Space requirement: 3m² minimum for ensuite (tight but legal). Ventilation: Part F requires mechanical extract (100mm inline fan, £250 installed) venting through roof or soffit.
Full structural assessment and Building Regs compliance
Tell us your roof type and what space you need