How Much Does a Loft Conversion Cost
- Nick Gradica
- Jan 30, 2024
- 1 min read
The cost of a loft conversion in London tends to be higher than the national average due to factors such as higher living costs, increased prices of materials and labour, and potentially more stringent building regulations. Below is a summary of the costs of a typical loft conversion.
However, it's important to note that these are just rough estimates, and actual costs can vary based on several factors.
Loft Conversion Enabling Works Cost
Strip out and remove existing fixtures and fittings in the loft affected by the works away from the site. Cut out a section of the rear roof elevation to open up the area for the new dormer. Supply skips to remove away from site rubbish created during the works. Provide a Portable Loo for the site operatives for the duration of the works. Supply and fit scaffolding as required for the duration of the works to enable works at a high level.
Cost £6870
Loft Conversion Structural Steels Cost
Supply and fit new structural steel beams as shown on Structural Engineer drawings and calculations. Supply and fit all pad stones, bolts and chemical fixings as specified by the Structural Engineer
Cost £6650
Loft Sub Floor Cost
Construct new suspended timber floor consisting of; Structural Graded C24 Treated Carcassing Timber 47mm x 200mm webbed into the new structural steels, Wire Netting Galvanised BS443 50mm Mesh to the underside of new timber floor, Isover Spacesaver Insulation 200mm between the new joist and 18mm X 2440mm X 1220mm WBP Plywood screw fixed at 300mm centres on top of the new floor joist.
Cost £4380
Dormer Cheeks Fibre Cement Slates Cost
Construct new dormer cheeks consisting of; 600mm x 300mm Fibre Cement Slates, on Treated Timber Batten 25mm x 38mm, on Cromar Classic Breather Membrane 115gsm, on 12mm Hardwood External Grade Plywood B/BB and 12mm Magply Euroclass A1 Non-Combustible Board on the neighbours' side within 1m, on Structural Graded C24 Treated Carcassing Timber 47mm x 100mm at 400mm centres, including lead flashing and doubling up timbers around window openings.
Cost £6620
Dormer EPDM Warm Flat Roof Cost
Construct Warm Flat roof comprising; 11mm OSB3 Ply Deck on, 120mm Ecotherm Eco-Versal Insulation or similar on, Vapour Control Layer on, 18mm OSB3 Ply Decking, laid on firrings to give a 1:40 fall fixed on 47mm x 175mm grade C24 joist at 400 centres. Supply and fit EPDM Roof Covering, including all the necessary trims and flashing as required. Remove existing rainwater goods affected by the works. Where necessary, adapt existing rainwater pipes and extend them to suit the new layout. Supply and fit new White/Black UPVC Fascia and Soffit Boards. Supply and fit 112mm half-round gutter with necessary connections and fixings. Supply and fit 68mm downpipes with necessary connections and fixings. All rainwater goods are to be in black UPVC plastic.
Cost £6120
Pitched Roof Fibre Cement Slates Cost
Construct new pitched roof comprising; Fibre Cement Slate 600mm x 300mm, including eaves and half round ridge tiles on, 25mm x 38mm roof battens on, breathable membrane on, 47mm x 175mm grade C24 rafters. Remove existing rainwater goods affected by the works. Where necessary, adapt existing rainwater pipes and extend them to suit the new layout. Supply and fit new UPVc White/Black Fascias and Soffit Boards. Supply and fit 112mm half-round gutter with necessary connections and fixings. Supply and fit 68mm downpipes with necessary connections and fixings. All rainwater goods are to be in black UPVC plastic.
Cost £6950
Loft Conversion Double Glazing Cost
Supply and fit new double glazed White Velux Rooflights and UPVC Casement windows to front and rear elevations as follow;
1No x Velux CK04 White Central Pivot Windows
2No x Velux MK06 White Central Pivot Windows
1No x UPVC Casement Window to Ensuite (Frosted)
1No x UPVC Casement Window to Bedroom
Cost £3290
Internal Stud Walls Cost
Construct new timber stud partition to form new ensuite and landing with 47mm x 100mm Structural Graded C24 Treated Carcassing Timber softwood sole and head plates and studs at 400mm centres. Provide noggins at 1200mm centres.
Cost £2100
Electrical BG Screwless Faceplates Cost
Run new 2.5mm Twin and Earth cabling for double sockets to the Loft Room.
Run new 1.5mm Twin and Earth cabling for lighting to the Loft Room.
Supply and fit a new extractor fan to the Ensuite with an over-run timer and isolating switch.
Run 3 core and earth for Mains fed smoke alarms to each landing and Heat Alarm in the kitchen.
Supply and fit new up-to-date Fuseboard to meet current building regulations and issue NIC EIC Electrical Certificate on completion.
Supply and fit BG Nexus Screwless or similar faceplates for double sockets and light switch as follow;
6No. Double Socket (2 with USB)
16No. Spot Lights (4No. IP65)
1No. Storage Light
1No. Dimmer Light Switch
4No. Normal Switches
3No. Mains Smoke Alarm
1No.Mains Heat Alarm
1No. Extractor Fan with Timer
1No. Ubiquiti WiFi Access Point
Cost £3950
Central Heating & En-Suite Cost
Adapt and extend the existing central heating system and pipework into the new loft area. Supply and fit of a high-output convector radiator with TRV Vales in the new room. Adapt and extend existing soil 900mm above any window. Adapt existing hot and cold water pipes and extend new poly-pipe pipe to feed the new bathroom sanitary ware. Run a new 32/40mm waste pipe for the new basin and shower. Run a new 110mm soil pipe to pick up the waste from the bathroom sanitary ware and extend to the nearest existing soil pipe, ensuring that there is adequate fall. Fit only, client-supplied Bathroom Fittings, including Shower Tray, WC, Wash Hand Basin, Mixer and Taps.
Cost £3650
Loft Conversion Insulation & Dry-Lining
Pitched Roof: 100mm Ecotherm Eco-Versal Insulation between rafters and 52.5mm Ecotherm Eco-Liner Insulated Plasterboard to the underside of rafters.
Ceiling: 12.5mm British Gypsum FireLine Plasterboard to the underside of rafters
Dormer Cheeks: 80mm Ecotherm Eco-Versal Insulation between timbers studs and 37.5mm Ecotherm Eco-Liner Insulated Plasterboard on top. Gable Wall: Supply and fit 25mm PIR Insulated Plasterboard.
Internal Walls: 75mm Rockwool RWA45 Insulation between partitions.12mm HardieBacker Tile Board is on the bathroom side, and the 12.5mm British Gypsum Wallboard Plasterboard is on the other side.
Cost £5740
Loft Conversion Plastering Cost
Plaster the walls and ceiling in the new Loft Conversion with two coats of British Thistle Multi-finish, including making good with Bonding/Hardwall where necessary.
Cost £2980
Loft Conversion Carpentry 2nd Fix Cost
Supply and fit new traditional staircase in Pine and Ply positioned above the existing flight. The new stairs will be fitted with a handrail, newel post and spindles, which will match the character of your home. The handmade staircase will be constructed and installed in accordance with the latest building and safety regulations. Supply and fit new door frame and architrave. Supply and fit Premdor Internal Moulded Smooth 4 Panel FD30 Fire Door. Supply three hinges per door and door handle. Bathroom and ensuite door to be fitted with additional privacy lock. Style of doors and handles to be confirmed. Supply and fit Torus/Ogee Skirting Board MDF White Primed 18mm x 144mm
Cost £5150
En-Suite Tiling Cost
Prepare floor and walls ready for tiling. apply a coat of waterproof sealer around the shower area. supply and fit Ditra Matting to flooring area. Fit only, client-supplied floor and wall tiles. Tile adhesive and grouting are included in the cost. For Mosaic tiles, there will be an additional cost.
Cost £2850
Loft Conversion Painting and Decorating Cost
Prepare and decorate ceilings and walls in the Loft with one under oat and two topcoats using Little Greene Emulsion Paint. Prepare and decorate woodwork with one undercoat and two topcoats using Little Green Eggshell/Gloss.
Cost £3560
Legal and Professional Fees
The legal and professional fees associated with a loft conversion in London can vary depending on factors such as the complexity of the project, the need for planning permissions, and the specific services required. Here are some of the potential legal and professional fees you might encounter:
1. Architectural Fees:
- Hiring an architect to design plans for your loft conversion is a common expense. Architectural fees in London can range from 7% to 15% of the total construction cost, but this can vary based on the complexity of the project and the architect's experience.
2. Structural Engineer Fees:
- If structural modifications are needed, you may need the services of a structural engineer. Their fees can vary but are typically based on an hourly rate or a percentage of the project cost.
3. Planning Permission Fees:
- If your loft conversion requires planning permission, there will be fees associated with submitting and obtaining approval. The fees can vary depending on the type and scope of the project.
4. Building Regulations Fees:
- You may need to pay fees for building control services to ensure that your loft conversion meets all necessary regulations and standards.
5. Party Wall Agreement Fees:
- If your property shares a wall with a neighboring property, you may need a Party Wall Agreement. The fees for this agreement can vary, and it's advisable to consult with a surveyor.
6. Legal Fees:
- You might need legal advice, especially if there are complex legal issues related to your loft conversion. Legal fees can vary based on the complexity of the situation.
7. Insurance:
- Consider insurance costs to cover any potential liabilities during the construction phase.
It's crucial to consult with professionals early in the planning stages to get a clear understanding of the specific legal and professional services you'll need for your loft conversion. These costs can significantly contribute to the overall budget, and proper planning can help avoid surprises.