The answer is not always straightforward. Some projects can be completed without a planning application, while others will need formal approval before work begins.

The type of property, the work being carried out and even the area of London you live in can all affect what is required. A straightforward internal refurbishment may need no planning permission at all, while an extension, loft conversion or external alteration can bring planning rules into play.

At BRX London, we work across residential renovation, refurbishment and extension projects throughout London. Understanding the approvals required at the beginning of a project is an important part of keeping the build organised and avoiding unnecessary delays later on.

Here are the key things homeowners should understand before starting work.

If your renovation is entirely internal, planning permission will often not be required. Redecoration, replacing a kitchen, updating bathrooms, installing new flooring and many other internal improvements can normally be carried out without making a planning application.

Even significant internal changes do not automatically require planning permission. However, the position can change if the property is listed, if the work affects the external appearance, or if the proposal involves a material change of use.

It is also important not to confuse planning permission with Building Regulations. A project can require Building Regulations approval even when planning permission is not needed.

Many house extensions can be built under permitted development rights. These rights allow certain types of work to proceed without a full planning application, provided the proposal stays within specific limits and conditions.

For example, the size, height and position of an extension all matter. The rules also take account of the original house and previous extensions, so it is not always enough to look only at the work you are proposing now.

Larger rear extensions can also be subject to a prior approval process, where the local authority considers matters including the impact on adjoining properties. If the proposed extension falls outside permitted development limits, a householder planning application is likely to be required.

In London, where properties are often close together and sites can be constrained, establishing the planning position before finalising the construction programme is particularly important.

A loft conversion is another project that can often be completed under permitted development rights. This can include adding rooflights or creating additional roof volume, provided the work complies with the relevant limits and conditions.

For roof enlargements, the permitted development rules include limits on additional roof volume. Broadly, this is up to 40 cubic metres for terraced houses and 50 cubic metres for other houses, alongside requirements relating to height, position, materials and the existing roof.

A design that exceeds the permitted development rules, or a property where those rights are restricted, may require planning permission instead. This is why the design should be checked against the planning position before structural work is ordered or construction begins.

One of the most important distinctions in London is between houses and flats. Householder permitted development rights do not generally apply to flats and maisonettes in the same way they apply to houses.

That matters because London has a huge number of converted houses, mansion blocks and purpose-built flats. External alterations to a flat, changes affecting the building as a whole or more substantial works may therefore require planning permission even where a similar alteration to a house could potentially fall within permitted development.

Leasehold consent may also be required separately. Planning approval does not replace the need to comply with the terms of your lease or obtain any necessary freeholder or management company consent.

London contains hundreds of conservation areas, created to protect places with particular architectural or historic character. If your property sits within one, additional planning restrictions may apply.

Some permitted development rights are more limited on designated land, and local authorities can also use Article 4 Directions to remove particular permitted development rights in specific areas. Works that might be straightforward elsewhere can therefore require an application in a conservation area.

This is especially relevant when changing windows, doors, roofs, external materials or the appearance of the front of a property. The safest approach is to check the property’s planning constraints at the design stage rather than assuming that neighbouring alterations automatically set a precedent.

A listed building is a separate consideration from a conservation area. If a property is listed, works that affect its special architectural or historic interest may require Listed Building Consent.

This can apply to internal as well as external work. Removing historic features, changing layouts, altering windows or doors and carrying out structural changes can all require specialist consideration.

For listed properties, the design and approval process should be dealt with carefully before construction begins. Starting unauthorised work to a listed building can create serious legal and practical problems.

This is probably the most common area of confusion for homeowners. Planning permission is primarily concerned with whether a development or alteration is acceptable in planning terms. Building Regulations are concerned with how building work is designed and constructed so that it meets required standards.

Building Regulations can apply to extensions, loft conversions and structural alterations, as well as many changes to drainage, electrics, heating, windows, doors and other parts of a renovation.

You may therefore need Building Regulations approval even when planning permission is not required. Equally, receiving planning permission does not mean that the technical construction details have been approved under the Building Regulations.

Both need to be considered as part of the pre-construction process.

Removing walls, forming new openings and changing the structure of a property may not necessarily require planning permission, but that does not mean the work can simply begin.

Structural calculations may be required, Building Control may need to inspect the work and, depending on the location of the structure, the Party Wall etc. Act 1996 may also need to be considered.

For example, an extension built close to a neighbouring property, excavation near an adjoining owner’s foundations or work to a shared party wall can create separate obligations. These processes should be identified early because they can affect when construction is able to start.

If a project is intended to proceed under permitted development, homeowners may choose to apply for a Lawful Development Certificate. This is not the same as planning permission. Instead, it provides formal confirmation that the proposed development is lawful.

For larger renovations, this can provide useful certainty and a clear record for the future, particularly when the property is later sold or refinanced.

Permitted development rules can be technical, so where there is any uncertainty it is sensible to obtain professional planning advice or confirmation from the relevant local planning authority before proceeding.

The biggest practical lesson is simple: do not leave planning and approvals until the builders are ready to start.

Drawings, planning requirements, structural information, Building Control and any party wall matters should be reviewed as part of the pre-construction stage. If these are still unresolved once demolition or structural work begins, the project can quickly lose momentum.

Good preparation also makes quotations more accurate. When the contractor is pricing from a coordinated set of drawings and a clearly defined scope, there is less room for assumptions, missing information and avoidable variations during the build.

Every property and project is different, particularly in London. Before starting a renovation, establish exactly what permissions apply to your home and make sure the design, approvals and construction information are aligned.

At BRX London, we work closely with clients, architects, consultants and Building Control throughout the renovation process, helping projects move from the design stage into construction with a clear and coordinated plan.

General guidance only. Planning requirements depend on the individual property, proposal and local authority. Homeowners should obtain project-specific advice before commencing work.