Free online calculator
Loft conversion cost calculator for London
Enter the size of the loft and what you want in it, and see a London budget for the conversion with labour, materials and VAT included.
Start the calculatorCall 07353 373753
- London rates, 2026 prices
- VAT included
- No sign-up to see the price
Calculator
Work out your loft conversion cost
Answer the questions below. The estimate updates as you go, and you only leave your details if you want an exact price.
Loft conversion cost calculator
Choose the type of loft conversion, the floor area, rooms, bathrooms, stairs, roof windows, lights and sockets, and see a London price including VAT.
What is included
What the calculator counts
- The floor area of the loft.
- A bathroom or en-suite, in the same detail as the bathroom calculator.
- Eaves storage, smoke alarms, extra insulation, asbestos survey, planning fee and party wall awards.
- New partition walls, by length and height.
- The total shown with VAT, with the figure before VAT underneath.
- Drawings and structural calculations can be uploaded with your request.
Price terms
What is in the price
Every estimate is for supply and fit: we buy the materials and fittings, do the work with our own team and clear up. This is what the price covers, what it leaves out, and what we need from you.
Included: what we supply and do
- Labour of our own plumbers, gas engineers, electricians, tilers, carpenters and decorators.
- Building materials: pipework, cables, consumer unit parts, plasterboard, plaster, adhesive, grout, screws, sealant, paint and primer.
- Steelwork, floor joists, insulation, dormer or roof windows, stairs, fire doors, plasterboard, electrics, heating and decoration.
- Every fitting you tick in the calculator at the finish level you choose (standard, mid-range or premium), bought by us and fitted.
- Waste removal and skips, protection of floors and furniture, site set-up and project management.
- Testing and certificates: gas safety, electrical (Part P) and building control notices where the work needs them.
- VAT at 20%: the range shown is the figure you would pay.
Not included
- Architect drawings, structural engineer, planning fees and party wall surveyors, unless you tick them in the calculator.
- Scaffolding licence from the council if the road is used, and party wall awards unless ticked.
- Structural problems found after opening up: rot, damp, asbestos, old wiring not up to standard. They are priced separately after the survey.
- Furniture, curtains, blinds, light bulbs in decorative fittings and loose appliances that are not built in.
- Parking permits and congestion charges, which are charged at cost.
From you
- If you prefer to buy your own tiles, sanitaryware, kitchen units or appliances, tell us: we fit them and take their cost out of the price. Supply-only items must be on site before the work starts.
- Access to the property, water and electricity during the work.
- Decisions on colours, tiles and fittings before the work starts, so nothing waits on a delivery.
Budget
What changes the price most
The size of the loft
Floor area drives the cost of flooring, insulation, plastering and decoration, so it is the first thing the calculator asks for.
Adding a bathroom
An en-suite adds plumbing, drainage, tiling and ventilation. Placing it above an existing bathroom keeps the pipe runs short.
Structure and permissions
Steelwork, the position of the staircase and changes to the roof depend on the building. If you already have drawings or an engineer's calculation, upload them and the estimate is checked against them.
How it works
From estimate to fixed price
Answer the questions
Sizes, finishes and fittings. It takes a few minutes and you can change any answer.
See the estimate
A price range with VAT, with a breakdown of what it is made of.
Send it to us
Add your contact details, and a drawing if you have one, to ask for an exact price.
Free survey, fixed price
We visit, measure and confirm a fixed price before any work starts.
Read how we carry out home refurbishment in London, or see our hourly rates for smaller jobs on the pricing page.
Questions
Loft conversion cost calculator questions
How much does a loft conversion cost in London?
It depends on the floor area, on whether a bathroom is included and on the structural work the roof needs. The calculator shows a budget range with VAT.
Do I need planning permission for a loft conversion?
Many loft conversions fall under permitted development, but flats, conservation areas and larger roof changes usually need planning permission. Building regulations approval is always required. Check with your local council before work starts.
Can I upload my architect's drawings?
Yes. Upload a PDF or a photo, up to 10 MB, and it goes to our estimator together with your request.
Is the estimate a fixed quote?
No. It is a budget range. The fixed price is confirmed after a free survey.
What is included in the price?
Labour, every material and fitting you tick at the finish level you choose, waste removal, protection, project management, certificates and VAT. Drawings, planning fees, party wall awards and surveys are included only when you tick them in the calculator. The full list is in the section "What is in the price" on this page.
Can I buy the materials myself?
Yes. If you buy your own tiles, sanitaryware, units or appliances we fit them and take their cost out of the price. They must be on site before the work starts. Everything else, from pipework to paint, is supplied by us.
Why Plumbery
Qualified, insured and upfront about price
Every engineer we send is registered or qualified for the trade they work in, and you can check the details before anyone starts.
- Fully insuredEvery job is covered by our insurance.
- Rates published in advanceOur hourly rates are on the pricing page. Nothing starts until you agree the rate.
- Paperwork includedGas safety certificates and electrical records are provided on completion.
- Registered companyPlumbery Ltd, company no. 11677583, registered in England and Wales.
Renovation
Kitchens, bathrooms and extensions
One team for the fitting, plumbing, gas and electrics, with an itemised written quote before work starts.
