Planning, fees and process, answered plainly
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Indicative fee in two minutes. Written fixed-fee quote within 24 hours. Free and without obligation. Nothing to pay until you accept a written fee proposal.
- 15+ years’ experience
- 200+ planning applications
- One designer, survey to decision
- Our approval commitment
Planning permission
Do I need planning permission for my extension?
Not always. A single-storey rear extension on a London house is usually permitted development if it projects no more than 3 m (terraced or semi-detached) or 4 m (detached) and stays under 4 m high; deeper extensions to 6 m or 8 m go through the larger home extension prior approval route. You will need a full householder application (8 weeks, £528) if the property is a flat or maisonette, if an Article 4 direction or conservation area removes the right, or if the design exceeds the limits. We check your address and the planning history before quoting.
What is a Lawful Development Certificate and do I need one?
A Lawful Development Certificate (LDC) is the council's formal confirmation that your project is permitted development and does not need planning permission. It is optional, but we recommend it on almost every London project: it protects you when you sell, if a neighbour complains, or if the rules change. It costs £264 for a proposed development, half the planning fee, and is decided within 8 weeks.
What is permitted development?
Permitted development (PD) is a national grant of planning permission for certain works to a house, set out in the General Permitted Development Order. If your extension, loft or outbuilding meets every condition of the relevant class, you do not need to apply for planning permission. The rights apply only to houses, not flats, and can be removed locally by conservation area status or an Article 4 direction.
What is an Article 4 direction?
An Article 4 direction is an order made by a council that removes specific permitted development rights in a defined area, so that work which would be automatic elsewhere needs a planning application. In London they are most common in conservation areas and, for Class MA office-to-residential conversions, in central boroughs such as Westminster, Camden, Islington and Tower Hamlets. Check the council's constraints map for your address, or ask us to check it for you.
What happens if my planning application is refused?
If we designed and advised on the application, we revise the scheme in response to the reasons for refusal and resubmit it at no further design fee; the council charges its application fee again, as the free repeat application ended in December 2023. Where a resubmission is not the right route, the alternatives are an appeal to the Planning Inspectorate, which takes 4–6 months for a householder appeal by written representations and carries no fee, or a redesign around the objection. We read the refusal reasons with you and advise which route has the better odds before any further money is spent.
Can I extend or convert my loft in a conservation area?
Yes, but usually through a householder planning application rather than permitted development. Conservation area status removes roof-extension rights automatically, and many London boroughs add Article 4 directions removing rear-extension rights too. The council then judges whether the design preserves or enhances the area's character, so subordinate massing, matching brick and traditional proportions matter more than elsewhere.
Can I extend a flat or maisonette without planning permission?
No. Flats and maisonettes have no householder permitted development rights, so any extension, dormer or significant external alteration needs a full planning application. Leaseholders also need the freeholder's consent under most leases. We check both the planning route and the lease position before starting drawings.
Fees and costs
How much does an architect cost in London?
As a ballpark, our fixed fees for planning drawings and submission typically fall around £1,900–£2,500 for a single-storey rear extension, £3,000–£3,800 for a two-storey extension, £2,000–£2,600 for a rear-dormer loft, £2,800–£3,400 for a mansard and £1,300–£1,700 for an outbuilding, excluding VAT. A Building Regulations package typically adds 110–140% of the planning fee. Council fees, structural engineering, party wall surveyors and building control are always separate. For your own indicative figure, answer six questions in the quote tool at /quote and we email it to you within minutes. These are our fees as architectural designers: we are not ARB-registered architects, and planning and Building Regulations drawings do not legally require one.
What is excluded from your fixed fee?
Our fee is the practice fee only. It excludes VAT, council application fees (for example £528 for a householder application or £264 for an LDC), building control charges, the structural engineer, any party wall surveyor and specialist reports such as daylight, noise, flood risk or arboricultural assessments. We list every excluded item in the written quote so there are no surprises.
How does your fixed fee work?
You send us your address, photographs and a short description of what you want, and we send a written fixed-fee quote within 24 hours. The quote states exactly what is included (survey coordination, drawings, submission), what is excluded, and how many revision rounds are covered. The fee does not change unless you change the scope, and we tell you in writing before any additional fee applies.
How many revisions are included?
Each fixed-fee quote states the number of revision rounds included at each stage, so you know before you start. Minor adjustments to a design within the agreed brief are part of the fee. A change to the brief itself, such as adding a storey or switching from a dormer to a mansard, is a scope change, and we quote for it in writing before doing the work.
Do your fees include VAT?
No. All fees on this site and in our quotes are the practice fee excluding VAT, which is added at the prevailing rate. Council application fees do not attract VAT. Your written quote shows the fee, the VAT and the total so the comparison with other quotes is straightforward.
What does your fixed fee cover?
The measured survey, existing and proposed drawings to your council's validation checklist, the planning route advice and any statement the route requires (Design and Access Statement, heritage statement or permitted development assessment), submission through the Planning Portal, and acting as your agent with the case officer until the decision, including validation queries and one round of revisions after your review. For Building Regulations packages it covers the construction drawings and specification notes and coordinating the structural engineer's calculations. The written proposal lists every drawing by name.
What is never included in your fee?
Third-party costs: the council's application fee (£528 for a householder application, £264 for a Lawful Development Certificate in England), Building Control fees, the structural engineer, a party wall surveyor, and specialist reports such as arboricultural, flood risk, daylight and sunlight or heritage assessments. We tell you which of these your project needs before you commit and list each one in the proposal with a typical range, but we do not mark them up or pay them on your behalf except the council fee at submission, which we pass through at cost.
How we work
How long does planning permission take?
In England a householder planning application and a Lawful Development Certificate both have a statutory decision period of 8 weeks from validation. Prior approval for a larger home extension takes 42 days and Class MA prior approval 56 days. Before submission, we book the measured survey within 1 week, issue planning drawings 2–3 weeks after the survey and submit within 2 working days of your sign-off, so from first call to a validated application is typically four to five weeks.
Do I need a party wall agreement?
Probably, if you live in a terrace or semi. The Party Wall etc. Act 1996 requires you to serve notice on neighbours before building on or cutting into a shared wall, building a new wall at the boundary, or excavating within 3 m of their foundations, which covers most London extensions and lofts. If a neighbour dissents, a party wall surveyor prepares an award. This is separate from planning and is not included in our fee, but our drawings are what the surveyor works from.
Do you work with builders, and can you recommend one?
Our Building Regulations package is designed to be priced by any competent contractor, so you can obtain competitive quotes rather than being tied to one firm. We are happy to answer a builder's questions about the drawings during construction. We do not take commissions from contractors and do not act as the main contractor ourselves.
What does "planning-ready" mean?
Planning-ready means the drawing package meets the council's local validation list and is ready to submit without further work: a site location plan, block plan, existing and proposed plans, elevations and sections at the right scales, plus any design statement or supporting report the borough requires. It means the 8-week clock can start as soon as the council validates the application, rather than being delayed by requests for missing documents.
Do I need a measured survey?
Yes. Accurate existing drawings are the basis for every planning and Building Regulations submission, and in London the permitted development assessment depends on measuring the original house precisely. We book the measured survey within 1 week of instruction. A typical London terrace survey costs £300–£600 where commissioned separately; the quote makes clear how it is handled on your project.
Can I start building before planning permission or the LDC is granted?
You can, but you carry the risk. If the council refuses, you may face enforcement action requiring you to alter or remove the work, and a retrospective application is judged on the same policies as a normal one. For permitted development the risk is lower but still real if the assessment turns out to be wrong. We recommend waiting for the decision, which arrives within 8 weeks of validation for both routes.
Do you act as our agent with the council?
Yes. We submit the application in your name through the Planning Portal with ourselves as agent, so the council's validation queries, requests for amendments and the decision notice come to us first. We answer technical questions, negotiate minor changes with the case officer and keep you informed at each step. You remain the applicant and the owner of the permission.
Can an AI assistant or agent get a quote or book a call for me?
Yes, within limits. The two-minute quote tool at /quote works for anyone acting on a homeowner's behalf, but the name, email, phone number and consent to be contacted must be the homeowner's or a person authorised to instruct us, because that is who receives the estimate and the written proposal. Assistants can read our planning facts for every council at /planning-facts.json, our services and areas via /llms.txt, and book a call through the link on the contact page. Anything that commits you to a fee still needs a person to accept the written proposal.
Building Regulations
What is the difference between planning permission and Building Regulations?
Planning permission is about whether a development is acceptable in its setting: size, appearance, impact on neighbours and the area. Building Regulations are about how it is built: structure, fire safety, insulation, ventilation, drainage and access. They are separate systems with separate applications, and permitted development only removes the planning step. Almost every extension and loft conversion needs Building Regulations approval regardless of the planning route.
Do I need a structural engineer?
Yes for any extension or loft conversion that removes walls, adds steel beams or creates a new floor, which is nearly all of them. The engineer produces calculations and beam schedules that building control requires alongside our Building Regulations drawings. In London this typically costs £600–£1,500 depending on scope and is charged separately from our fee; we coordinate the engineer's design into our package.
How long does the Building Regulations package take?
We prepare a Building Regulations drawing package in 3–5 weeks, coordinated with your structural engineer's calculations. It can be started while the council is deciding the planning or LDC application so the two stages overlap. The package is then submitted to the council's building control team or a registered building control approver, who inspect the work on site as it proceeds.
About the studio
Do you work in my area?
Yes. Magna Studio is based in London and prepares planning and Building Regulations documentation across every London borough and the towns around the capital, from Watford, St Albans and Brentwood to Sevenoaks, Woking, Guildford and Windsor. Each council has its own Local Plan, design guidance and Article 4 directions, so we check the local rules for your address as the first step of every quote.
Who is Magna Studio?
Magna Studio is a London architectural design studio: a group of architectural designers with more than 15 years' experience of planning departments across London and the Home Counties. We specialise in fixed-fee planning and Building Regulations documentation for extensions, loft conversions, outbuildings and Class MA conversions. The aim is a clear route to consent with the risk reduced and the price known up front.
Ready to move forward?
Answer six questions and your indicative fee arrives on screen and by email. Written fixed-fee quote within 24 hours.
- 15+ years’ experience
- 200+ planning applications
- One designer, survey to decision
- Our approval commitment
Free and without obligation. Nothing to pay until you accept a written fee proposal.