Planning Permission vs Building Regulations: What’s the Difference?
Updated: Sep 26
If you’re planning an extension or making changes to your home, you’ll probably hear two terms early on: planning permission and Building Regulations approval.
It’s easy to assume they are different names for the same thing. They are separate processes, however, and getting planning permission does not mean your project is ready to build.
At Reid Design Limited, we help homeowners across Timperley, Sale, Altrincham and Greater Manchester understand these stages and develop their designs from initial ideas into detailed technical drawings.
Using examples from one of our projects, here’s how the two stages differ—and why both matter.
What does planning permission cover?
Planning considers whether a proposed development is acceptable in its location.
For a home extension, this can include its size, height, appearance, materials and relationship with neighbouring properties. Privacy, overlooking, daylight and the character of the surrounding area can also be relevant.
Planning drawings communicate what is there now and what you want to change. They typically include existing and proposed floor plans, elevations, and site information.
In the examples accompanying this article, the existing layout provides the starting point. The proposed drawings then show how the house would change, including the additional space, roof shapes, windows and external materials.
These drawings help the homeowner and planning officer understand the proposal and its relationship with the surrounding buildings.
Proposed planning drawings show the new layout, roof forms, windows and external appearance.
Where do 3D visualisations fit in?
Reading a floor plan or elevation doesn’t come naturally to everyone. A 3D visualisation can make a proposal much easier to understand.
It helps communicate the materials, proportions and overall volume of the building—often referred to as its “massing”. It can also help clients compare design choices and give planners a clearer picture of the proposal.
A visualisation supports the design discussion, but it does not replace accurate drawings or the technical information needed for construction.
What do Building Regulations cover?
Building Regulations set requirements for building work, covering matters such as structural safety, fire safety, ventilation, energy efficiency and drainage.
They are separate from planning permission. An extension or alteration may need Building Regulations approval even when a planning application is not required. GOV.UK: Building Regulations approval
At this stage, the drawings develop beyond the layout and appearance of the proposal to explain the construction and demonstrate how the relevant requirements will be addressed.
For example, the design may need to establish:
How walls, floors and roofs are constructed and insulated.
How new openings and loads are supported.
How the extension connects to the existing building.
How moisture, ventilation and drainage are dealt with.
What fire precautions and escape arrangements are required.
The exact information depends on the property and the work being proposed.
Why do the Building Regulations drawings look so much more detailed?
The technical drawings shown here illustrate the next stage of the same project.
The ground-floor and first-floor plans contain dimensions, construction notes and references to individual details. The sections cut through the building to explain relationships that cannot be fully understood from a floor plan alone.
They show how the different parts of the design come together, including floor levels, roof construction and connections between existing and proposed work.
This detail has a practical purpose. Decisions that look straightforward on a planning drawing often need careful coordination before they can be built.
A large opening between an existing house and a new extension, for example, raises questions about support, beam depth, floor levels and the space available for insulation and finishes.
Working with the structural engineer
Architectural and structural design need to work together.
Depending on the project, a structural engineer may design foundations, beams, columns or other supporting elements and provide the associated calculations.
Our role includes coordinating that information with the architectural drawings. The position and size of structural elements can affect ceiling heights, openings, room layouts and the way new construction meets the existing house.
Resolving these relationships early helps the team identify conflicts before they become problems on site.
Every site has its own challenges
Technical design also needs to respond to the conditions at the property.
The ground-floor drawing in this example includes a gas-barrier detail. Where ground-gas protection is required, the membrane and its junctions need to be considered as part of the construction.
Other projects may involve existing drains, culverts, unusual ground conditions or services running through the proposed building area. These can require investigation, specialist advice and, where applicable, separate consents.
Such constraints should be investigated as early as possible. They can influence the initial design as well as the later technical details.
Sometimes further information only becomes available when work begins and existing construction is exposed. Where included in our appointment, we help coordinate design responses with the contractor, structural engineer and other relevant specialists.
Does permitted development mean I can skip Building Regulations?
No. Permitted development is a planning route; it does not remove applicable Building Regulations requirements. Government householder guidance
For example, a qualifying extension may not need a householder planning application, but its structure, insulation, ventilation and other technical aspects still need to comply.
Our homeowner’s guide to permitted development explains that planning route in more detail.
Can a builder quote from planning drawings?
Planning drawings can help a builder provide an initial budget estimate. However, they generally leave more construction decisions unresolved than a developed technical package.
If different builders make different assumptions about those details, their prices may be difficult to compare.
Coordinated drawings, specifications and a clear schedule of what is included give builders a firmer basis for pricing. The information needed for Building Regulations is an important part of that, although it may not include every finish, fitting or contractual detail needed for a complete tender package.
It is worth agreeing what level of information your project needs before requesting detailed quotations.
Does approval of the drawings finish the process?
No—the work on site matters too.
Under a full-plans route, the building control body checks the submitted information. Site inspections then form part of checking the work as it progresses, with the appropriate completion or final certificate issued when the relevant requirements have been satisfied. Approval of drawings alone is not the same as completion sign-off. Planning Portal: Full plans
Planning conditions and any other necessary permissions must also be addressed. If the design changes during technical development or construction, those changes may need checking against the planning permission.
From your first ideas to detailed drawings
Understanding these stages makes it easier to plan your project, appoint the right people and know what you are paying for.
Planning establishes whether the proposal is acceptable in planning terms. Technical design then develops the information needed to address construction and Building Regulations requirements. Considering both from the outset helps produce a more coordinated design.
At Reid Design Limited, we help homeowners develop practical layouts, understand their planning route and progress their projects through the relevant design stages.
If you’re thinking about an extension, loft conversion or alterations to your home, I’d love to hear your ideas. Get in touch for a free initial feasibility consultation, and we can explore the next steps together.
This article provides general guidance for domestic projects in England. The drawings illustrate a particular project; construction details and approval requirements must be assessed for each property.
Comments