Loft conversion drawings from £625
Velux, rear dormer or hip-to-gable: we measure the house, draw the loft as it will be, work out whether it needs planning permission and submit it, for one fixed fee.
£625 £475 drawings + £150 survey (£625 total), no VAT to add
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The short answer
Loft conversion drawings show the council and your builder what the new room is: the plan, the roof, the stairs that reach it and the way out in a fire. Many London lofts fit permitted development, which is limited by roof volume. Our fee is £475 drawings + £150 survey (£625 total), no VAT to add, and the council fee, if one is due, is separate.
Loft conversion drawings
from £625
- Drawings
- £475
- Measured survey
- £150
- Total you pay
- £625
- VAT
- None to add
- A measured survey of the house, the roof and the neighbours’ windows that face it
- Existing and proposed plans, elevations and a section through the new stair
- A volume calculation that tests the loft against permitted development
- The Lawful Development Certificate or planning application, with forms, submitted for you
- Your choice of Velux, rear dormer, hip-to-gable or L-shaped dormer, drawn from the same survey
- An independent check of every sheet, and free redraws of our drawings until approval
£475 drawings + £150 survey (£625 total). A starting fee: we confirm one fixed figure after checking your address. The council’s own fee, where there is one, is paid to the council.
Get my fixed feeHow a loft conversion job runs with us
Roof check
We look at the address first: conservation area, listed building, Article 4 direction, past extensions that have already used up volume.
Survey the loft and the stair below
One visit measures the roof, the ridge and eaves heights and the landing where the new stair must land.
Choose the shape
We show a Velux scheme and a dormer scheme side by side, with the volume each uses, and you choose in writing.
Drawings and submission
We draw the chosen scheme and submit it for you, as a Lawful Development Certificate or a householder application.
Building regulations next
After the decision we can draw the technical set: structure, fire escape, insulation and the stair.
Does a loft conversion need planning permission?
Often it does not. Roof additions fall under Class B of the permitted development order, which allows a loft to grow by up to 40 cubic metres in a terraced house and 50 cubic metres in any other house, measured against the original roof space. That volume includes any earlier loft work, which is why we ask about it before we draw.
The right is lost in a conservation area, and a dormer cannot rise above the existing ridge or reach past the plane of a roof slope that fronts the road. Flats have no permitted development rights for lofts at all. When the right is lost, a householder application is the route, and we say so before you pay for anything beyond the survey.
- Terrace: 40 cubic metres. Semi-detached or detached: 50 cubic metres
- No part higher than the existing ridge
- Side-facing windows obscure-glazed, opening only above 1.7 metres from the floor
- Not allowed on article 2(3) land, which includes conservation areas
The stair and the fire escape decide the layout
A loft is only a bedroom if you can get up to it and out of it. The stair needs 2 metres of headroom, though Approved Document K lets a loft conversion reduce that to 1.9 metres at the centre of the stair, falling to 1.8 metres at its side, where there is no more room.
Once the new floor sits more than 4.5 metres above the ground, Approved Document B asks for a protected escape route down the house: fire doors and 30-minute partitions around the stair. That is why we draw the stair first and the loft around it, not the other way round.
Velux, dormer or hip-to-gable: what each one costs you in volume
A Velux conversion keeps the roof as it is and spends almost none of the volume allowance, but it only works where the room already has height. A rear dormer buys standing room at the back for a good slice of the allowance, and a hip-to-gable on a semi uses even more.
Because we draw each option from one survey, you see the volume and the headroom for every shape before choosing. If the loft is already past the allowance because of an earlier extension, we tell you at the start and draw a householder application instead.
Loft conversion rules in numbers
40 m³
Largest roof-space increase permitted development allows a terraced house.
Source: GPDO 2015, Schedule 2, Part 1, Class B: roof additions (legislation.gov.uk)
50 m³
The same limit for a semi-detached or detached house.
Source: GPDO 2015, Schedule 2, Part 1, Class B: roof additions (legislation.gov.uk)
0.2 m
How far a dormer should sit back from the eaves, measured along the roof slope, so far as practicable.
Source: GPDO 2015, Schedule 2, Part 1, Class B: roof additions (legislation.gov.uk)
1.7 m
Side-facing roof windows must be obscure-glazed and open only more than 1.7 metres above the floor.
Source: GPDO 2015, Schedule 2, Part 1, Class B: roof additions (legislation.gov.uk)
4.5 m
A new storey above this height triggers a protected escape route with fire doors and 30-minute partitions.
Source: Approved Document B (fire safety) volume 1: Dwellings (GOV.UK)
1.9 m
Reduced stair headroom allowed in a loft conversion at the centre line, falling to 1.8 m at the side.
Source: Approved Document K: protection from falling, collision and impact (GOV.UK)
0.15
Maximum U-value, in W/m²K, for a new roof element in an existing dwelling.
Source: Approved Document L volume 1: conservation of fuel and power, dwellings (GOV.UK)
2 months
Notice you must give a neighbour before work on a party wall, such as cutting in a steel beam.
Source: Party Wall etc. Act 1996, section 3 (legislation.gov.uk)
145,600
Householder decisions made by English councils in the year to June 2026, half of all planning decisions.
Source: Planning applications in England: April to June 2026 (GOV.UK)
Questions about loft conversions
Do I need a Lawful Development Certificate if the loft is permitted development?
You do not have to have one, but you should. A buyer’s solicitor will ask for proof that the loft was lawful, and a certificate is that proof. For a future development the council fee is half the full application fee, according to the GOV.UK fees guidance.
Can I convert the loft if my neighbour has already done theirs?
Yes, each house is judged on its own roof. A neighbour’s dormer does not use up your allowance, though it can help show what the street already accepts if you need a planning application.
Will I need a structural engineer?
Almost always. New floor joists, steel beams at the ridge or across the dormer opening need calculations for building control, and we draw to match them. See structural calculations.
Do I need to tell my neighbours?
Permitted development does not require it, but the Party Wall Act can, where beams bear on a shared wall. We prepare the notices if you need them.
Find out how big your loft can be
Send the address and a photo of the back of the house. We reply with the route and a fixed fee, from £475 drawings + £150 survey (£625 total).