Planning applications rely on accurate existing-condition survey drawings. Whether you’re extending a home, converting a loft, changing the use of a building or undertaking a commercial refurbishment, architects and planning consultants require reliable measured survey information before preparing planning drawings.

This guide explains what drawings are typically required, why accuracy matters, and how professional survey data gives your architect and planning consultant a reliable base to work from — reducing the risk of delays, amendments and validation failures.

What Survey Is Required for a Planning Application?

Most planning applications require accurate existing-condition drawings of the property. Depending on the project, this may include a measured building survey, a topographical survey, an OS location plan or a combination of these survey types to support planning, design and validation requirements.

From residential extensions and loft conversions to commercial change of use and listed building consent, XP Surveys provides the measured building surveys, topographical surveys and OS site plans needed to support planning applications across London and the South East.

Planning authorities need to understand what currently exists on a site before they can assess what you are proposing to change. Without accurate drawings of the existing building, officers cannot properly evaluate the impact of proposed works on the building, its neighbours or the surrounding area.

Existing-condition drawings allow the planning authority to:

• Compare the proposed design directly against the current building
• Assess the scale and massing of proposed extensions or alterations
• Verify compliance with local planning policies and design guides
• Review the impact on neighbouring properties for overlooking and right of light
• Confirm heritage and conservation area requirements are being met

Missing or inaccurate drawings are one of the most common reasons planning applications are delayed or invalidated at submission. A professional survey eliminates this risk by providing verified, accurate existing-condition data your architect can rely on from day one.

Most applications will only be validated — accepted for review — when the correct drawings have been submitted at the right scale and in the required format. Getting this right at the outset saves weeks of delay and avoids the cost of amendments later in the process.

Existing Floor Plans

Floor plans show the internal layout at each level — walls, openings, rooms, staircases and key dimensions. Planning authorities use these to understand the current configuration and compare it with the proposed layout. Typically submitted at 1:50 or 1:100 scale.

Existing Elevations

Elevations show the external faces of the building — front, rear and side — including heights, window and door positions, rooflines and architectural features. Both existing and proposed elevations are required so the planning officer can directly compare before and after. Typically at 1:50 or 1:100 scale.

Existing Sections

Sections are vertical cut-throughs showing the relationship between floors, ceiling heights, floor thicknesses and structural elements. Particularly important for loft conversions, basement extensions and any works affecting floor-to-ceiling heights.

Roof Plans

Roof plans show the building from above including roof shape, ridge and eaves lines, rooflights, chimney stacks and drainage outlets. Commonly required for loft conversions, dormer extensions and flat roof alterations.

Site Plan / Block Plan

A site plan shows the building in the context of its plot — boundaries, neighbouring buildings, access routes, trees and external features. Most applications require a site plan at 1:500 or 1:1250 scale, often based on Ordnance Survey mapping. For projects involving extensions into the garden or changes to the site boundary, a topographical survey may also be required.

Submitted Drawing Scales

• Location plan: 1:1250 or 1:2500
• Site/block plan: 1:500 or 1:200
• Floor plans, elevations & sections: 1:50 or 1:100

All XP Surveys drawings are produced at the scales required for planning submission as standard.

Residential Extensions

Side return, rear, wraparound and double-storey extensions require existing floor plans, elevations and a site plan. For terraced and semi-detached properties, accurate party wall positions and neighbour relationships are particularly important for planning assessment.

Loft Conversions

Loft conversions require existing and proposed floor plans at loft level, roof plans, sections showing ceiling heights and floor thicknesses, and external elevations showing any dormer or rooflight additions. Accurate ridge and eaves heights are critical for permitted development compliance.

Basement Extensions

Basement projects are among the most technically demanding for planning. Most London boroughs require a Basement Impact Assessment (BIA) relying on accurate level data, floor-to-ceiling heights and structural information. Survey accuracy here is critical — errors in level data can cause fundamental design problems that are extremely costly to resolve during construction.

Change of Use

Commercial-to-residential conversions, barn conversions and other change-of-use applications require accurate existing floor plans and elevations showing the building in its current use alongside the proposed layout for the new use.

Listed Buildings & Conservation Areas

Applications involving listed buildings or conservation areas require a higher standard of documentation. Planning authorities and heritage officers expect detailed drawings recording existing building fabric precisely — including architectural features, material details and structural elements. Our laser scanning workflow is particularly well suited to heritage properties, capturing period details with millimetre accuracy without physical contact with sensitive fabric.

New Builds & Development Sites

For new build projects or development sites, a topographical survey is typically required. This records ground levels, boundaries, trees, drainage and existing site features needed for the planning submission.

For simple projects some architects measure a property themselves. However inaccurate existing-condition drawings can cause planning applications to be refused, design errors that only emerge during construction and coordination problems between the architect, structural engineer and contractor.

A professional measured building survey eliminates these risks. Using laser scanning technology, our surveys achieve ±2mm positional accuracy — far beyond what hand measurement can reliably deliver — producing coordinated CAD drawings your architect can use directly without additional processing.

For listed buildings, conservation areas, basement extensions or any project where accuracy is critical, a professional survey is essential rather than optional.

How Much Does a Planning Survey Cost?

Survey costs depend on property size, complexity and deliverables required. Typical costs:

• 2–3 bedroom house (floor plans & elevations): from £250 + VAT
• 4–5 bedroom house including sections & roof plan: from £600 + VAT
• Commercial or listed buildings: quoted individually based on scope

Use our instant online quote tool for an estimate based on your property address, or contact us to discuss your project.

How Long Does It Take?

Standard turnaround for CAD-ready drawings is 3–5 working days from survey completion. A typical planning application programme:

• Day 1–2: Survey booked, site visit scheduled within 48 hours
• Day 2–3: Site survey completed
• Day 5–7: CAD drawings delivered to architect
• Week 2–3: Architect produces proposed drawings
• Week 3–4: Planning application submitted

Getting the survey done early avoids delays and gives your architect a reliable base from day one.

Do I always need a professional survey for planning permission?

Not always — for very simple projects on straightforward buildings, an architect may measure the property themselves. However for listed buildings, conservation areas, basement extensions or any project where accuracy is critical, a professional survey is strongly recommended. Inaccurate drawings are one of the most common causes of planning delays and construction errors.

What is the difference between a measured survey and a topographical survey for planning?

A measured building survey records the existing building — floor plans, elevations, sections and internal dimensions. A topographical survey records the site — ground levels, boundaries, trees, drainage and external features. Many planning applications require both, particularly for extensions that affect the garden or site boundary. See our Topographical Surveys page for full detail.

Can you provide OS site plans for planning applications?

Yes. OS location plans and block plans are available as an add-on to any survey instruction — delivered as PDF and .dwg files at the scales required by the Planning Portal.

How accurate do planning drawings need to be?

Planning Portal guidance does not specify a minimum accuracy tolerance, but drawings must be a true and accurate representation of the existing building. For listed buildings and heritage applications, planning authorities and conservation officers expect a significantly higher standard of accuracy and detail. Our laser scanning surveys achieve ±2mm positional accuracy as standard.

Can the same survey data be used for construction as well as planning?

Yes. This is one of the key advantages of a laser-scanned measured survey. The same data that supports the planning application can be used by the architect through RIBA Stages 2–4 for technical design, structural coordination and construction documentation — avoiding the need for a repeat survey later.

Which areas do you cover for planning surveys?

XP Surveys provides planning application surveys across London, Berkshire, Buckinghamshire, Oxfordshire, Surrey and the wider South East. Contact us to confirm coverage for your specific location.

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Get a Planning Application Survey Quote

XP Surveys provides survey drawings for planning applications across London and the South East:

• Measured building surveys — floor plans, elevations & sections
• Topographical surveys for site and ground level data
• OS location plans and block plans
• Revit BIM models for complex or heritage projects

We’ll provide a clear quote covering:

• Survey scope and deliverables
• Site visit date within 48 hours
• CAD drawings delivered in 3–5 working days
• Fixed pricing with no hidden fees

Serving London, Berkshire, Buckinghamshire, Oxfordshire, Surrey and the South East.
Call us on 0333 335 5085 or use the contact form to discuss your requirements.