Planning, fees and process, answered plainly

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.

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.

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.

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.

You can amend the design and resubmit, appeal to the Planning Inspectorate, or redesign around the objection. A householder appeal by written representations typically takes 4–6 months and there is no fee to appeal. We read the refusal reasons with you and advise which route has the better odds before any further money is spent.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.