2025 Survey Costs (ex VAT)
| Property | Standard | Fast Track (+25%) | Rush (+50%) | | --- | --- | --- | --- | | 2–3 bed | £400–£600 | £500–£750 | £600–£900 | | 4+ bed | £500–£800 | £625–£1,000 | £750–£1,200 | | Commercial | £800–£1,500 | £1,000–£1,875 | £1,200–£2,250 |
Survey Deliverables Reference
| Deliverable | Format | Use | | --- | --- | --- | | Floor plans | DWG + PDF | Design reference | | Elevations | DWG + PDF | Planning submission | | Sections | DWG + PDF | Building regulations | | Site plan | DWG + PDF | Planning boundary |
Measured Building Survey for House Extensions: What Homeowners Must Know
If you are planning a house extension — a rear extension, a loft conversion, a side return, or a full two-storey extension — you will need a measured building survey of your existing property before the design can begin. This article explains what homeowners need to know about commissioning a measured building survey for a house extension.
Why Do I Need a Survey Before an Extension?
You need a measured building survey before an extension because the architect needs accurate existing drawings to design against. Without accurate existing drawings, the design is based on guesswork — and guesswork leads to problems when construction begins.
An architect designing an extension needs to know the exact dimensions of the existing property: the floor areas, the ceiling heights, the positions of windows and doors, the thickness of walls, and the structural configuration. This information is not reliably available from estate agent particulars, Land Registry plans, or the original design drawings — which may not reflect the property as it actually exists.
A measured building survey captures the property as it currently exists. Every dimension is verified against the physical building, so the architect can be confident that the design will fit. The result is a smoother planning application, fewer construction problems, and a better outcome for your project.
What Does the Survey Capture?
A measured building survey for a house extension captures:
- Floor plans of all levels, showing all room layouts, wall positions, windows, and doors
- External elevation drawings, showing the front, rear, and side elevations
- Building section(s), showing ceiling heights, floor levels, and the relationship between different parts of the property
- The positions of structural elements — load-bearing walls, chimney breasts, and any existing structural modifications
- Additional details of any original features that are relevant to the proposed works
The survey data is delivered as CAD drawings in DWG format and PDF, which the architect can use directly in their design software. The drawings are dimensioned and verified against the survey data, so every dimension can be relied upon.
When Should I Commission the Survey?
Commission the measured building survey as early as possible in the project — ideally before you instruct an architect. The survey data is one of the first things the architect needs to begin design work, and commissioning it early avoids a delay at the start of the design stage.
If you are planning a rear extension, the survey should be commissioned before you have detailed plans — the architect needs the existing drawings to develop the proposed drawings. If you commission the survey after the architect has begun work, you will need to wait for the survey before the design can progress.
For a straightforward rear or side extension, the survey can typically be completed within one to two weeks of instruction — including the site visit and the processing of the drawings. For more complex projects, allow more time.
What About the Site Levels?
If your extension involves significant excavation — a basement, a lower ground floor extension, or works near a boundary — you will also need a topographical survey that captures the levels of your property and the surrounding ground. The topographical survey provides the level data that the structural engineer needs to design the foundations.
A combined measured building and topographical survey — commissioned together from the same provider — is typically more cost-effective than commissioning the two surveys separately, and ensures that all survey data is referenced to the same coordinate system and datum.
Do I Need a Survey for a Loft Conversion?
Yes. A loft conversion requires accurate existing drawings — the floor plans, the elevations, and crucially the section through the building that shows the roof structure, the ceiling height, and the available headroom. Without these drawings, the architect cannot determine whether a loft conversion is feasible, what type of loft conversion is possible, and where the dormer or roof light should be positioned.
The measured building survey for a loft conversion also captures the positions of any existing chimneys, dormers, or roof features that affect the proposed works. This information is important for the structural engineer who will design the loft conversion structure.
Do I Need a Survey for a Planning Application?
Most planning applications for house extensions require accurate existing drawings as part of the submission. Your local planning authority will validate the planning application against the existing drawings you submit — if the drawings are inaccurate or incomplete, the application may be rejected or delayed.
A measured building survey from a qualified surveying company produces drawings that meet the planning authority's validation requirements. The drawings are produced to a professional standard, dimensioned and verified against the physical building, and in the format required by the planning authority.
How Much Does a Survey for a House Extension Cost?
The cost of a measured building survey for a house extension depends on the size and complexity of your property. Here are indicative costs:
- Small flat or bedsit (up to 50 sqm): from around 300 to 500 pounds
- Two-bedroom flat or small terraced house: from around 400 to 700 pounds
- Three-bedroom terraced or semi-detached house: from around 600 to 1,000 pounds
- Four to five bedroom detached house: from around 1,000 to 1,500 pounds
For a combined measured building and topographical survey, add approximately 300 to 600 pounds to the measured building survey cost.
All icelabz quotes are fixed-fee — the price you are quoted is the price you pay, with no hidden charges.
How Long Does the Survey Take?
For a typical three-bedroom house, the site visit takes three to four hours. The drawings are typically delivered within five to ten working days of the site visit. The total time from instruction to delivery is typically two to three weeks.
For larger or more complex properties — a detached house with a large garden, a property with a complex Victorian layout, a property with extensive original features — the timeline may be longer. We will confirm the expected timeline when you contact us.
Who Conducts the Survey?
A qualified surveyor from icelabz will conduct the survey. The surveyor will visit your property at a time agreed with you, conduct the measurement survey, and return to process the data and produce the drawings. The drawings are reviewed by a senior surveyor before delivery to ensure quality.
You do not normally need to be present during the survey — though it is helpful if you are, to answer questions about the property and to point out any areas of particular concern.
What File Formats Will I Receive?
You will receive:
- DWG files in AutoCAD format — the industry standard for architectural drawings, compatible with most design software
- PDF files — viewable in any web browser or PDF reader, suitable for sharing with your architect, your planning authority, or your builder
You can forward the DWG files directly to your architect, who will use them as the basis for the extension design.
Can I Use the Drawings for Multiple Purposes?
The measured building survey drawings can be used for multiple purposes throughout your project:
- The initial design stage: the architect uses the existing drawings to develop the proposed drawings
- The planning application: the existing and proposed drawings are submitted as part of the planning application
- The building regulations application: accurate existing drawings are required for the building regulations submission
- The party wall awards: if works affect a neighbouring property, the existing drawings are shared with the adjoining owners' surveyors
- Construction: the builder uses the drawings for pricing and construction
- Future reference: the drawings are a permanent record of your property
Commission the survey once, use it many times.
Getting Started
To commission a measured building survey for your house extension project, contact icelabz with the property address and a brief description of the proposed works. We will confirm the scope, provide a fixed-fee quote, and schedule the site visit at a time that suits you.
For homeowners in London and the South East, we typically have availability within five to ten working days of instruction. For urgent requirements, we offer same-week delivery where possible.
Contact us to discuss your extension project and receive a fixed-fee quote.