Practical design from first survey to technical drawings.
Measured surveys, extension design, planning drawings and Building Regulations information developed with buildability, the existing property and the likely construction process in mind.
A successful extension needs to work on paper and on site
The drawing is not the end product. It is information that has to become a real building.
Williams Survey & Design combines technical drawing and surveying with more than 30 years of practical construction experience. Proposals are developed with consideration for buildability, existing property constraints, structural coordination, construction detailing and the likely sequence of work.
Our aim is to make effective use of the available space while remaining realistic about the property, the client's objectives, budget and statutory requirements.
More than simply reproducing a sketch. If a proposal appears impractical, disproportionately complicated or likely to create avoidable construction problems, we will explain that and discuss more workable options.
Good proposed drawings start with dependable existing information
The existing building is measured and recorded to the level of detail required by the project. For many extension and alteration schemes this includes floor plans and external elevations, with sections or additional detail where they are needed.
That base information then supports planning design, structural coordination and the later technical drawing stage rather than relying on approximate dimensions or assumptions.
Explore measured surveys →Choose the stage your project actually needs
Planning Feasibility / Pre-Design Advice
Early-stage review where the route, constraints or viability need to be understood before committing to full design work.
- Initial project discussion
- Property and proposal review
- Planning history / constraint considerations where relevant
- Planning, permitted-development or LDC route advice
- Practical feasibility and next-step advice
Measured Survey, Design & Planning / LDC
For a straightforward domestic extension or alteration where the design and planning submission can be developed as one defined package.
- Measured property survey
- Existing plans and elevations as required
- Proposed floor plans and elevations
- Site / block and location plans
- Practical design development
- Planning, Prior Approval or LDC drawing package as appropriate
- Application preparation and submission where included in the quotation
Building Regulations Drawings & Specification
Technical information for a straightforward domestic project once the design and planning position have been established.
- Detailed proposed plans and elevations as required
- Construction sections
- Foundation, wall, floor and roof build-ups
- Insulation and thermal-performance notes
- Ventilation and fire-safety provisions
- Drainage information where within scope
- General construction notes and key details
- Coordination with structural information where supplied
Two-storey extensions, loft conversions, substantial structural alterations, unusual construction and small developments are quoted individually where the scope or technical complexity is materially greater. No VAT is currently added to Williams Survey & Design professional fees.
Residential design and alteration work
The appropriate service depends on the property, proposed work and whether planning permission, permitted development confirmation or Building Regulations approval is required.
Planning drawings and Building Regulations drawings do different jobs
Planning / LDC Drawings
Planning drawings principally explain the scale, appearance and relationship of the proposal to the existing property and its surroundings.
- Existing and proposed floor plans
- Existing and proposed elevations
- Roof plans where required
- Location and site / block plans
- Key dimensions and annotations
- Application information relevant to the agreed scope
Planning permission can never be guaranteed. The decision rests with the local planning authority. We can advise on the likely route and foreseeable issues, then prepare a clear submission based on the information available.
Building Regulations Drawings
Building Regulations information goes further into how the proposed work is intended to be constructed and how the relevant technical requirements are addressed.
- Construction build-ups and sections
- Thermal and insulation information
- Ventilation provisions
- Fire-safety considerations
- Drainage information where applicable
- Key construction junctions and details
- Structural information coordinated where supplied
The exact level of information depends on the project and agreed scope. Building Control remains responsible for the statutory approval / inspection process.
Clear drawings that explain the proposal properly
A planning set needs to show the local planning authority what exists, what is changing and how the proposal relates to the building and its surroundings.
Depending on the scheme, that can include existing and proposed floor plans, elevations, roof information, site / block plans and the supporting application information required for the chosen route.
Where appropriate, we also consider whether a full planning application is actually necessary or whether permitted development, Prior Approval or a Lawful Development Certificate is a more suitable route.
The correct route should be established before the drawings are submitted
Some domestic extensions and alterations may be carried out under permitted development rights, while others require planning permission. Where certainty is important, a Lawful Development Certificate may be appropriate.
A clear route from first discussion to technical design
Not every project requires every stage, so the appointment is defined around what the project actually needs.
Initial discussion
We discuss the property, what you want to achieve, your priorities, budget and known constraints.
Review & quotation
We review the available information and issue a written quotation defining the proposed scope, fee and exclusions.
Measured survey
Where required, the existing property is measured and suitable base plans / elevations are prepared.
Design development
The proposed layout and appearance are developed around the brief, existing building and likely planning route.
Planning submission
Once agreed, the relevant planning, LDC or Prior Approval information is prepared and submitted where included.
Technical design
Where commissioned, the agreed proposal is developed into more detailed Building Regulations information.
Coordination
Structural and other specialist information is coordinated with the drawing package where required and supplied.
Construction support
Where separately agreed, we can assist with drawing queries, revisions, contractor coordination or project support.
From first conversation to construction information
More than just drawings
Technical information should help the contractor understand what is intended and help foreseeable construction issues to be considered before work reaches site.
We consider how the proposed work interfaces with the existing building, how junctions are likely to be formed, how structural information affects the design and what further information may be required.
- Existing construction and practical access constraints
- Foundation, floor, wall and roof build-ups
- Insulation continuity and key junctions
- Roof geometry, drainage and weathering details
- Openings and structural coordination
- Relationship between new and existing construction
- Practical sequencing and buildability where relevant
Where specialist calculations, design or investigation are required, those services are identified rather than being implied as part of the architectural / technical drawing appointment.
The Building Regulations stage adds the construction information
This is where the design is developed beyond appearance and room layout into construction build-ups, key junctions, insulation, ventilation, drainage, fire-safety provisions and coordination with structural information where required.
The purpose is not to fill a drawing with notes for the sake of it. The information should help Building Control, the contractor and other professionals understand the intended construction and where specialist information still sits outside our appointment.
Get a Building Regulations guide price →One project can involve several different types of information
Measured survey, site information, planning design, elevations, sections and technical details all need to relate to the same real building.
What is included is confirmed before instruction
Williams Survey & Design professional fee
Your written quotation sets out the measured survey, design, drawing, submission and technical services included in our appointment.
- Scope tailored to the actual project
- Fixed professional fee confirmed before instruction
- No VAT currently added to our professional fees
- Any assumptions or material exclusions stated clearly
Potential third-party / statutory costs
Depending on the project, separate costs may include:
- Planning / LDC / Prior Approval application fee
- Planning Portal service charges
- Building Control fees
- Structural Engineer
- Party Wall surveyor
- Energy / glazing calculations
- Drainage or build-over requirements
- Ecology, arboricultural or other specialist reports where required
Not every project needs all of these. We identify foreseeable requirements as the project develops.
Design decisions and construction budget should be considered together.
Floor area is only part of the cost. Structural openings, glazing, roof design, kitchens, site constraints and specification can materially affect the build budget.
Our separate 2026 guide explains realistic early-stage construction allowances and some of the items that often sit outside a simple £/m² figure.
Read the Extension Cost & Budget GuidePractical construction experience behind the drawings
Planning an extension, conversion or alteration?
Use the guide-price calculator for an initial indication, or send us the property address and a brief outline of what you want to achieve. We will review the project and confirm the appropriate scope and fixed professional fee.
Guide fees are subject to the property, project scope, planning risk, survey requirements and technical complexity. Planning approval and Building Regulations approval cannot be guaranteed. Statutory and third-party fees are separate unless expressly included in the written quotation.