One of the most common questions homeowners ask when starting a residential project is what drawings are actually required before work can begin.
The answer depends on the type of project, whether planning permission is required and how far through the process the project has progressed. However, most home extensions will typically involve two key drawing stages:
Understanding the difference between these stages early on can help make the process feel significantly clearer and easier to navigate.
Measured Surveys & Existing Drawings
Before any proposed design work can begin, accurate existing drawings of the property are usually required.
At Downland Studio, this begins with a detailed digital measured survey. Specialist technology captures the layout, wall thicknesses, openings and key dimensions, with precision laser checks where required. We interpret the information to produce the existing Revit model and architectural drawings, including:
Existing floor plans
Existing elevations
Site information
The checked existing model supports design and technical development from the outset. Digital measurement helps us move efficiently from the site visit into design and reduce unnecessary repeat visits. A PDF copy of your measured floor plan is also added to your Client Portal.
Planning Drawings
Planning drawings are typically the first set of proposed drawings prepared during a residential project.
These drawings focus on the overall design, layout and appearance of the proposal and are used either:
For a householder planning application
To assess permitted development compliance
To support a Lawful Development Certificate application
Planning drawing packages commonly include:
Proposed floor plans
Proposed elevations
Site plans
Location plans
Depending on the project, additional information may sometimes also be required.
What Are Planning Drawings Used For?
Planning drawings help communicate the proposal clearly to the local authority and demonstrate how the project relates to the existing property and surrounding area.
When reviewing an application, planning officers are generally considering things such as:
Scale and appearance
Impact on neighbouring properties
Privacy and overlooking
Relationship to the street scene
Local planning policy
Planning drawings are therefore primarily concerned with the overall proposal rather than technical construction details.
Building Regulations Drawings
Once planning approval has been secured — or where planning permission is not required — projects will usually progress into a more detailed technical design stage.
Building Regulations drawings are significantly more detailed than planning drawings and are prepared for:
Building Control approval
Construction purposes
Coordination with builders and structural engineers
Technical drawing packages commonly include:
Construction sections
Structural coordination
Insulation specifications
Drainage information
Technical junction details
Compliance information
These drawings provide the technical information required to construct the project safely and compliantly.
Can Builders Work From Planning Drawings Alone?
In most cases, no.
Planning drawings alone are usually not detailed enough for construction and generally do not contain the technical information required for Building Regulations approval.
Attempting to build directly from planning drawings can often lead to:
Delays on site
Missing information
Unexpected costs
Coordination issues during construction
For this reason, most residential projects benefit from progressing into a dedicated technical drawing package before works begin.
Do I Need Structural Engineer Drawings Too?
Often, yes.
Many residential projects involving structural alterations, steel beams or loft conversions will also require input from a structural engineer.
Structural information is then typically coordinated into the Building Regulations drawing package as part of the wider technical design process.
Typical Residential Drawing Process
Although every project is slightly different, many residential projects across Worthing and West Sussex typically follow a process similar to:
Digital Measured Survey
Existing Drawings
Planning Drawings
Planning Approval (if required)
Building Regulations Drawings
Construction
Approaching projects in clear stages often makes the process feel much more manageable for homeowners.
See how a full project COMES TO LIFE HERE:
From drawings to the building contract
Technical drawings describe the proposed construction; administering the building contract is a separate role. Before your builder starts, decide how payments, changes and completion will be recorded. Downland Studio’s optional Contract Administration service provides a formal appointment for this work, while Project Support offers lighter, flexible assistance.
Starting the Process
For many homeowners, simply understanding which drawings are required and when can remove a huge amount of uncertainty at the beginning of a project.
At Downland Studio, projects are approached collaboratively and practically, helping homeowners across Worthing, West Sussex and the South Coast navigate residential design projects clearly from initial ideas through to construction-ready drawings.
If you’re considering a home extension and would like some honest advice before getting started, feel free to get in touch for an informal conversation.