Planning Drawings vs Building Regulations Drawings: The London Homeowner's Guide
Planning drawings vs building regulations drawings explained for London homes: what each set contains, who approves them, the order they come in, and how a coordinated package works.
Almost every London extension, loft or conversion needs two very different sets of drawings, and confusing them is the single most common reason a project stalls. Understanding planning drawings vs building regulations drawings early saves weeks of delay and avoids paying twice for work that could have been coordinated from the start. The two sets answer two different questions. Planning drawings ask: is this development acceptable here, in this street, in this London borough? Building regulations drawings ask: once it is allowed, how do we build it so it is structurally sound, warm, safe and compliant?
They are produced at different scales, contain different information, and are read by completely different people. Planning is assessed by your council's planning officers against local and national policy. Building regulations are assessed by building control, whether that is your borough's Local Authority Building Control (LABC) team or a private approved inspector. One set can be approved while the other is refused, and neither replaces the other.
This guide sets out exactly what each drawing package contains, when in the process you need it, who signs it off, and why having both prepared as one coordinated package by a single chartered practice is the most reliable route to a smooth, first-time approval on a London home.
What are planning drawings and what do they contain?
Planning drawings are the visual case you make to your London borough that a proposed change to your home is acceptable in principle. They are deliberately about form, scale, appearance and impact on neighbours, not about nuts and bolts. A planning officer uses them to judge the proposal against the local plan, the London Plan, conservation-area or article 4 constraints, and material considerations such as overlooking, loss of light and the character of the street.
Because the question is about acceptability rather than construction, planning drawings are drawn at coarser scales, typically 1:100 or 1:200, and pair existing and proposed views side by side so an officer can read the change at a glance. They do not show insulation build-ups, beam sizes or drainage falls; that detail belongs in the building regulations set.
- A location plan (usually 1:1250) with the site edged red, and a block plan (1:500)
- Existing and proposed floor plans showing the layout change
- Existing and proposed elevations for each affected face of the building
- Existing and proposed roof plans and, where relevant, site sections
- A design and access statement or heritage statement where the borough requires one
What are building regulations drawings and what do they contain?
Building regulations drawings are the technical construction set. Once a project is allowed in principle, these drawings prove it will be built to the standards in the Building Regulations 2010 and the Approved Documents, covering structure, fire safety, insulation and energy, ventilation, drainage, sound and safe access. They are what your builder actually works from on site and what building control inspects against.
This set is drawn at much finer scales, commonly 1:50 for plans and sections and 1:5 or 1:10 for details, because the whole point is to specify how each junction is constructed. Where planning shows a wall as a single line, building regs show its full make-up: blockwork, cavity, insulation, membrane and finish, each labelled to the relevant Approved Document.
The technical detail a building regs set must carry
Expect construction sections through walls, floors and the roof with insulation and U-value notes for Approved Document L, structural annotations coordinated with an engineer's calculations, fire-safety information such as protected escape routes and mains-wired interlinked smoke alarms under Approved Document B, and drainage layouts showing falls and connections under Approved Document H. Thermal, ventilation and Part O overheating notes complete the picture on most London homes.
How building regs drawings are checked and signed off
You can go the full plans route, where drawings are submitted and formally approved before work starts, or the building notice route, which is faster to start but relies on on-site inspection rather than pre-approved drawings. Either way, building control inspects at key stages, foundations, damp-proofing, drainage, structure and completion, and issues a completion certificate once satisfied. That certificate, not planning permission, is the document a future buyer's solicitor will ask to see.
Which comes first, and do you always need both?
The default order is planning first, then building regulations. There is little sense in engineering every construction detail before you know the council will accept the extension at all, so most London projects secure planning permission, or confirm permitted development rights, before the technical set is finalised. That said, the two are not strictly sequential: a good practice develops the building regs set as soon as the planning outcome is clear, and often runs preliminary structural thinking in parallel so nothing approved at planning turns out to be unbuildable.
You do not always need planning permission. Many London rear extensions, loft conversions and internal alterations fall under permitted development, and homeowners frequently confirm this with a lawful development certificate rather than a full planning application. But permitted development only removes the planning step; it never removes the building regulations step. Almost any structural or habitable-space work still needs building regs approval and a completion certificate, whether or not planning was required.
Who approves each set of drawings in London?
The two approvals sit with entirely separate bodies, which is why a project can clear one and fail the other. Planning is decided by your London borough's planning department, judging appearance, scale and neighbour impact against policy, typically over an eight-week determination period for a householder application. Building regulations are decided by building control, either the borough's LABC service or a private approved inspector you appoint, judging safety and compliance against the Approved Documents.
Because the assessors and the criteria differ, meeting one says nothing about the other. A loft that is perfectly acceptable in planning terms can still fail building control on escape-window sizing or fire separation, and a technically flawless extension can still be refused planning on overlooking grounds. Treating the two as one job, coordinated so decisions in one set never undermine the other, is exactly what avoids that trap.
This is also where using a chartered architectural technologist pays off in London: the same practice that argues the planning case understands the construction detail behind it, so the design that gets approved is the design that can actually be built.
How does a coordinated planning and building regs package work?
A coordinated package means both sets are produced from one shared, dimensionally accurate survey and model, by one team, so the proposed extension in your planning drawings is the exact same building described in your building regs set, to the millimetre. The floor levels, wall positions, opening sizes and roof geometry carry through unchanged, and the structural strategy is sanity-checked against the approved planning design rather than bolted on afterwards.
Split the work across two firms and you invite drift: a planning-only designer may draw a slender flat roof that an engineer later has to deepen, changing the very parapet height the council approved, forcing a fresh application. Coordination closes that gap. It also compresses the timeline, because the building regs set is already substantially developed the moment planning is granted, and it gives your builder one internally consistent pack to price and build from, reducing on-site queries and change orders.
| Aspect | Planning drawings | Building regulations drawings |
|---|---|---|
| Purpose | Prove the project is acceptable in principle | Prove the project is safe and buildable in detail |
| Typical contents | Location and block plans, existing and proposed plans, elevations, sections | Construction sections, U-value and insulation notes, structural and fire annotations, drainage |
| Approver | London borough planning department | Building control (LABC) or an approved inspector |
| Typical scale | 1:100 or 1:200, plus 1:1250 and 1:500 site plans | 1:50 plans and sections, 1:5 or 1:10 details |
| Timing | First, or confirmed via permitted development / LDC | After planning is clear, before and during construction |
| When needed | When the change affects appearance, scale or neighbours | For almost all structural or habitable-space work, always |
Related services: Planning Drawings, Building Regulations Drawings, Architectural Drawings.
Frequently asked questions
Do I need both planning drawings and building regulations drawings?+
Can I use my planning drawings to build from?+
Which comes first, planning or building regulations?+
Who approves building regulations drawings in London?+
Can planning be approved but building regs refused?+
How detailed do building regulations drawings need to be?+
Does permitted development mean I can skip building regulations?+
Why should one practice produce both sets of drawings?+
How long does each stage take on a typical London project?+
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