What is the difference between planning drawings and Building Regulations drawings?

If you’re planning an extension, renovation or new home, you’ll probably hear your architect talk about planning drawings and Building Regulations drawings.

Although they are both part of the architectural design process, they serve different purposes.

In simple terms:

Planning drawings show the planning authority what you want to build.

Building Regulations drawings show Building Control how the building will be constructed so that it complies with the regulations.

Understanding the difference is important because planning permission and Building Regulations approval are two separate processes, and getting planning permission does not mean that you can automatically start building.

What are planning drawings?

Planning drawings are prepared to explain the proposed development to the local planning authority.

Their purpose is to show what you are proposing to build and how it will look, so that the planning authority can assess whether the proposal is acceptable in planning terms.

For a typical house extension, planning drawings might include:

Existing and proposed floor plans
Existing and proposed elevations
Site location plan
Block plan
Sections through the building
Roof plans
Information about materials and finishes
Details of windows and doors
Other information required to support the planning application

The level of information required will depend on the project and the type of application being made.

At LA Hally Architect, once the initial design has been agreed, the planning stage involves developing the plans and elevations and adding further detail to the drawing set. We also consider potential Building Regulations issues at this stage, for example allowing sufficient space for insulation or likely structural elements.

This is important because planning drawings shouldn’t be designed in isolation from how the building will eventually be constructed.

What are Building Regulations drawings?

Building Regulations drawings are much more detailed.

Their purpose is to demonstrate that the proposed building work can comply with the requirements of the Building Regulations.

Rather than simply showing what the finished extension will look like, the drawings need to explain how important parts of the building will actually be constructed.

Depending on the project, this can include details relating to:

Wall construction
Roof construction
Floor construction
Insulation and thermal performance
Structural elements
Windows and doors
Drainage
Ventilation
Fire safety
Access
Electrical layouts
Lighting
Internal finishes and construction details

At LA Hally, the Building Control stage follows planning approval and involves producing detailed drawings for submission to Building Control. The practice works alongside the appointed structural engineer and other consultants to bring the relevant information together.

For most of its projects, LA Hally Architect submits a Full Plans application, allowing Building Control to check the technical information before construction begins.

Why aren’t planning drawings enough to build from?

This is one of the most important distinctions.

A planning application is primarily concerned with the principle, appearance and impact of the development.

A planning drawing might show that your proposed extension has a pitched roof, a particular type of window and a certain external material.

But for Building Regulations considerably more information is required to demonstrate how standards will be met.

For example, a planning drawing might show a wall approximately 340mm thick.

A Building Regulations drawing needs to establish how that wall is actually made up — including its structure, insulation, cavity, finishes and other components.

Similarly, a planning drawing might show a new roof.

The technical drawings need to establish how the roof is constructed, how it is insulated, how it connects to the existing building and how it meets the relevant Building Regulations requirements.

At LA Hally Architect our Building Control drawings are highly detailed, including construction information, insulation build-ups, electrical layouts, feature lighting and material details. These drawings are then enhanced further into Working Drawings, accompanied by a Schedule of Works, to ensure there can be no ambiguity around what the builder is expected to build and, consequently what the build cost actually includes.

Does planning permission mean I can start building?

No.

Planning permission and Building Regulations approval are separate.

Planning permission deals with whether the development is acceptable from a planning perspective.

Building Regulations deal with whether the building work meets the required technical standards.

You may therefore have planning permission for your extension but still need to complete the Building Regulations process before construction can begin.

There can also be projects that don’t require planning permission but still require Building Regulations approval.

For example, some extensions and alterations may fall within permitted development rights, meaning a planning application isn’t required. However, the construction work will still generally need to comply with Building Regulations.

This is one reason why it is important to consider both processes early in the design.

Why does LA Hally Architect consider Building Regulations during the planning stage?

Although the two applications are separate, the design of a building needs to work as a whole.

A design that looks excellent on a planning drawing may become difficult or expensive to construct if technical requirements haven’t been considered.

For example, the thickness of insulation can affect:

Wall thickness
Window positions
Floor levels
Roof design
Junctions with the existing building
Internal room dimensions

Similarly, structural requirements can affect openings, roof designs and the way a new extension connects to the existing property.

LA Hally Architect therefore tries to pre-empt potential Building Control issues, including allowing space for likely structural elements and insulation requirements, at the design stages of a project.

This helps the design move more smoothly from planning into technical design.

What happens after planning permission?

Once planning permission has been granted, the design can be developed in much greater technical detail.

At LA Hally Architect, this is when the Building Control drawings are prepared and coordinated with the structural engineer and other relevant consultants.

The drawings are then submitted to Building Control as part of the Building Regulations approval process.

For a Full Plans application, Building Control reviews the technical information and may request further information or amendments before approval.

This gives the project a greater degree of certainty before work starts on site.

What about the structural engineer?

An architect’s Building Regulations drawings are not a substitute for structural engineering calculations.

For example, if your extension involves removing an existing load-bearing wall or creating a large opening between the existing house and the extension, a structural engineer will normally need to design the structural solution.

At LA Hally Architect almost every project we work on requires a structural engineer and that it works closely with the appointed engineer during the Building Control stage.

The architect’s drawings and structural engineer’s information therefore need to work together.

Can the same drawings be used for getting builders’ quotes?

This is where detailed technical drawings become particularly valuable.

Once the design has progressed beyond planning and the technical information has been established, contractors can price the work much more accurately.

LA Hally Architect produces detailed construction drawings alongside a Schedule of Works, which sets out the work to be carried out and helps minimise the risk of items being missed from contractors’ quotations.

This can also make it much easier to compare quotations on a like-for-like basis.

A builder quoting from relatively simple planning drawings may have to make assumptions about how elements of the building will be constructed.

The more information that is available before construction starts, the fewer assumptions there should be.

Do I need both planning drawings and Building Regulations drawings?

For many extension and renovation projects, yes — but they are produced at different stages and for different purposes.

You don’t necessarily need planning permission for every project, but where planning permission is required, planning drawings will form part of the application.

Building Regulations approval is a separate matter and technical drawings will normally be required to demonstrate compliance.

Even where a project falls under permitted development and doesn’t need a planning application, it can still be worthwhile having an architect develop the design and technical information properly.

The simplest way to remember the difference

Think of it this way:

Planning drawings

“This is what we want to build.”

They explain:

What the building will look like
Where it will sit
How big it will be
How it relates to neighbouring properties
What materials and finishes are proposed

Building Regulations drawings

“This is how we are going to build it.”

They explain:

How the building will be constructed
How it will be insulated
How structural elements work
How it will deal with fire, ventilation and drainage
How it will comply with the Building Regulations
The detailed construction information needed by the builder

Why having an architect involved throughout can help

At LA Hally Architect, the aim is to take a project from the initial idea through to completion, rather than treating planning as the end of the design process.

The practice’s services cover concept design, planning applications, Building Control applications, technical detailing, tendering and contract administration. The level of involvement can be tailored to the individual project.

This means the transition from the initial concept, through planning and into technical design can be managed as one continuous process.

For a homeowner, that can help avoid a situation where a design receives planning permission only to discover later that it needs significant changes to make it technically viable or affordable to build.

Planning drawings vs Building Regulations drawings: at a glance

	Planning drawings	Building Regulations drawings
Main purpose	Obtain planning permission	Demonstrate Building Regulations compliance
Main audience	Local planning authority	Building Control and construction team
Focus	Design, appearance and planning considerations	Construction and technical performance
Level of detail	Sufficient to assess the proposal	Much more detailed
Structural information	Usually limited	Coordinated with structural engineer
Construction details	Limited	Extensive
Materials	General specification	Detailed specification
Used for construction?	Usually not sufficient on their own	Yes, alongside other project information

Thinking about an extension or renovation?

Planning and Building Regulations are separate processes, but they work best when considered together from the beginning.

A well-developed design should not only achieve planning approval; it should also be capable of being turned into a practical, buildable and cost-effective project.

At LA Hally Architect, we work with homeowners across Winchester, Hampshire and the surrounding areas, helping clients develop residential projects from initial ideas through planning, technical design and construction.

If you’re considering an extension, renovation or new home and aren’t sure what drawings or approvals you’ll need, get in touch with LA Hally Architect to discuss your project.