Quick summary: choosing a firm for planning permission for extensions
When you need help with planning permission for extensions, the best firm is usually one that can combine accurate drawings, practical design advice and a clear understanding of your local council’s planning policies. Depending on the project, that may be a specialist residential planning and drawing consultancy, an architectural practice, an architectural technologist or a chartered planning consultant.
- For a straightforward home extension: a specialist residential planning and drawing firm can often manage the survey, design, drawings and submission as one service.
- For a complex or sensitive site: a chartered planning consultant may be needed to prepare the planning case and respond to policy concerns.
- For a highly bespoke design: an architect or architectural technologist may provide more extensive design development.
- For the construction stage: check whether the firm also prepares Building Regulations drawings and coordinates structural calculations.
No reputable firm can guarantee approval. However, an experienced team should identify planning risks early, prepare a valid application and explain how your extension is likely to be assessed before you commit to building work.
Unsure who should handle your extension application?
Tell our team what you want to build and we will explain which drawings, applications and professional services your project is likely to need.
Which firms specialise in planning permission for extensions?
Several types of firm can help a homeowner secure consent for an extension. However, their services are not always identical. Some focus mainly on producing drawings, while others concentrate on planning policy, architectural design or the technical information needed for construction.
For many ordinary rear, side or two-storey extensions, the most convenient option is a residential planning and drawing consultancy that manages the project from measured survey through to submission. More complicated sites may also need an architect, architectural technologist, chartered town planner or specialist heritage adviser.
Before appointing anyone, it is sensible to establish whether full permission is actually required. Some house extensions may fall within permitted development rights, provided every relevant limit and condition is met. Our guide explaining how to check the likely consent route will help you understand the starting point.
Specialist planning and drawing firms for house extensions
A specialist residential planning and drawing firm concentrates on common homeowner projects such as rear extensions, side returns, kitchen extensions, loft conversions and garage conversions. These firms are often well suited to projects where you want one team to prepare the design and manage the application.
What a specialist extension firm may handle
- A measured survey of the existing property.
- Existing and proposed floor plans.
- Existing and proposed elevations.
- Roof plans and building sections where required.
- Location and block plans.
- Planning forms and supporting statements.
- Submission to the local planning authority.
- Communication with the planning case officer.
- Revisions where reasonable amendments are requested.
- Building Regulations drawings after the planning stage.
This joined-up service can reduce the risk of gaps between the designer, planning agent and technical drawing provider. It can also make it easier for you to understand who is responsible for each stage.
Nevertheless, check the precise scope before accepting a quotation. Some firms advertise an application package but charge separately for the measured survey, planning statement, amendments, mapping, council fee or Building Regulations work.
Architects, technologists and planning consultants
The right professional depends on the design challenge and the planning risk. In some cases, one firm employs several disciplines. In others, separate specialists work together.
Architectural practices
Architects are often a good choice where design quality, complex internal remodelling or a sensitive external appearance is particularly important. They can explore different layouts and materials, coordinate other consultants and develop the project beyond the planning stage.
However, not every architect specialises in domestic extensions or offers planning representation as part of the basic fee. Ask to see examples of similar householder projects and confirm who will prepare and submit the application.
Architectural technologists and technicians
Architectural technologists and experienced technicians frequently work on residential extensions. Their strength is often the practical development of drawings, construction details and regulatory information.
For a conventional extension, a technologist-led practice may offer a proportionate combination of design and technical knowledge. Even so, experience varies, so check their record with projects of a similar scale and property type.
Chartered planning consultants
A planning consultant focuses on planning law, local policy and the case for allowing development. Their involvement can be especially valuable where:
- the extension is larger than the council would normally expect,
- the property is in a conservation area or the green belt,
- permitted development rights have been restricted,
- neighbouring properties may be significantly affected,
- the proposal has already been refused, or
- you need a planning statement, negotiation or appeal advice.
A planning consultant does not necessarily prepare architectural drawings. Therefore, they may work alongside a drawing practice or architect. You can read more about that role in our homeowner guide to professional planning advice.
Design-and-build companies
Some builders and design-and-build companies offer plans and applications as part of a complete construction package. This can be convenient, but you should check who prepares the drawings and whether the design service is independent of the building contract.
In particular, establish what happens if planning consent is refused, if you decide not to use that contractor or if you want to obtain competitive building quotations.
Which type of firm is right for your extension?
There is no single professional category that is automatically best for every extension. Instead, match the firm to the complexity of the project and the support you need.
Provider comparison at a glance
| Type of firm | Often suitable for | Check before appointing |
|---|---|---|
| Residential planning and drawing consultancy | Straightforward rear, side and two-storey extensions | Whether design, submission and revisions are included |
| Architectural practice | Bespoke design, complicated layouts and sensitive homes | Domestic extension experience and full service scope |
| Architectural technologist | Practical design and detailed technical packages | Planning experience and who acts as the agent |
| Planning consultancy | Policy-sensitive, refused or contentious proposals | Whether separate drawings will be required |
| Design-and-build company | Homeowners wanting one construction provider | Drawing ownership, independence and exit terms |
What should a planning firm provide for an extension?
A good firm should do more than reproduce your sketch on a computer. It should investigate the property, explain the likely application route and develop a proposal that responds to the site.
Initial planning assessment
The first stage should consider the type of property, earlier extensions, planning history, local design guidance and any known restrictions. Previous additions matter because permitted development allowances are generally assessed against the original house, not simply the building as it stands today.
Accurate planning drawings
The application must clearly show the existing property and the proposed work. Depending on the scheme, this may include plans, elevations, roof information, sections and site drawings. Our extension application drawing checklist explains the typical documents in greater detail.
Application preparation and validation
The firm should identify the correct application type and prepare the documents required by the national and local validation lists. Missing information can prevent validation, which delays the point at which the council formally starts assessing the proposal.
Case officer communication
Once the application is live, the agent should monitor it and respond to reasonable questions. Where a small amendment could address an objection, an experienced firm should explain the advantages and disadvantages before changing the design.
Advice after the decision
Approval may include conditions that need to be followed. Alternatively, a refusal may require a revised application or an appeal. The firm should explain the decision notice clearly rather than treating the issue as closed on decision day.
Need drawings and planning support from one team?
We can review your extension idea, prepare the required plans and manage the submission with your local planning authority.
How to choose a planning firm for your extension
Comparing firms on price alone can be misleading. A lower quotation may exclude the survey, application handling or technical stage, while a higher fee may include several services.
Step-by-step appointment checklist
- Define the project. Decide whether you are considering a rear, side, front, wraparound or two-storey extension.
- Ask for an initial consent check. The firm should consider whether full permission, prior approval or a lawful development certificate may be appropriate.
- Review similar work. Look for projects involving comparable homes, constraints and local authorities.
- Confirm the named person responsible. Find out who will design the extension, prepare the plans and communicate with the council.
- Compare the full scope. Check surveys, drawings, revisions, supporting documents, submission and post-submission support.
- Check professional credentials and insurance. Ask about relevant qualifications, memberships and professional indemnity cover.
- Clarify ownership and cancellation terms. Make sure you understand whether you can use the drawings if you change builder or consultant.
- Agree the next stage. Establish whether the firm can prepare Building Regulations information once the planning position is settled.
Planning firm costs and extension application timescales
Fees vary according to the size of the property, the complexity of the design, the amount of survey work and the level of professional involvement. A simple drawing-and-submission service will usually cost less than a bespoke architectural commission or a planning case involving specialist reports.
Quick costs snapshot
- Initial advice: may be included in a package or charged as a separate consultation.
- Measured survey and planning drawings: normally form the main professional fee for a straightforward extension application.
- Planning consultant input: may be added where policy arguments or negotiations are needed.
- Council application charge: is normally separate from the consultant’s professional fee.
- Specialist reports: heritage, tree, ecology, flood-risk or transport documents may add to the cost where relevant.
- Technical design: Building Regulations plans and structural calculations are normally a later and separate stage.
Ask for a fixed written quotation where possible. It should clearly distinguish professional fees, council charges, mapping costs and third-party consultant fees.
After a valid householder application is submitted, the council follows its formal assessment process. However, the overall programme must also allow time for the survey, design decisions, drawing preparation, validation and any requested amendments. Our guide to application stages and decision periods explains how these parts fit together.
Why local council experience matters
National planning rules provide the overall framework, but councils also use local plans, supplementary planning documents, design guides and validation requirements. Consequently, the same extension can receive a different design response in different areas.
A suitable firm should know how to research the current local requirements rather than relying only on general permitted development diagrams. Local factors may include:
- limits on depth or bulk in local design guidance,
- rules for side extensions and gaps between buildings,
- conservation-area character requirements,
- green-belt policies,
- privacy, daylight and overbearing-impact tests,
- parking or access concerns, and
- local validation documents.
For a broader explanation of the system, see our complete homeowner planning overview.
FAQs: firms that handle planning permission for extensions
Do I need an architect to obtain permission for an extension?
No. There is no general requirement to appoint an architect for a householder application. Plans may also be prepared by an architectural technologist, technician or specialist residential drawing firm. The important points are competence, relevant experience and a clear service scope.
Is a planning consultant better than an architect for an extension?
They perform different roles. An architect usually concentrates on design and coordination, while a planning consultant focuses on policy and the planning case. Straightforward extensions may not need a separate consultant, whereas sensitive, refused or unusually large proposals may benefit from one.
Can a firm guarantee planning permission for my extension?
No reputable adviser should guarantee the council’s decision. The local planning authority remains responsible for determining the application. A professional firm can assess risk, improve the proposal and prepare a strong submission, but it cannot control the final outcome.
Do all extensions need planning permission?
No. Some extensions can be permitted development, provided the property qualifies and the proposal satisfies every limit and condition. Restrictions may apply to flats, maisonettes, listed buildings, designated land and properties where rights have been removed.
What size extension can I build without planning permission?
There is no single size that applies to every home. The assessment can depend on height, depth, width, position, materials, distance from boundaries, previous extensions and the type and location of the property. A project-specific check is safer than relying on one measurement.
Should the same firm prepare planning and Building Regulations drawings?
It can be helpful because the technical designer will already understand the approved proposal. However, confirm that the firm has suitable technical experience. Planning approval and Building Regulations compliance are separate, and most extensions still require Building Regulations approval.
What happens if my extension application is refused?
The first step is to understand every refusal reason. Depending on the circumstances, you may revise and resubmit the proposal or consider an appeal. Our guide to responding to an unfavourable council decision explains the main options.
Can the planning firm also deal with my neighbours?
The firm can explain the proposal and respond to planning comments, but this does not replace any separate obligations under the Party Wall etc. Act 1996. Planning permission and party wall procedures are different matters.
Comparing firms or quotations?
Send us your project outline and we will help you understand which planning and drawing services should be included.
Next steps and useful guides
Before appointing a firm, confirm the likely consent route, the drawing package and whether you will also need technical design services. These related guides will help:
- Follow the extension application process step by step
- Understand how an extension design develops from survey to approval
- See what drawing quotations commonly include
- Prepare for the Building Control stage after planning
- Learn how neighbour comments can affect an application
- Main provider types Residential planning and drawing firms, architects, architectural technologists, planning consultants and design-and-build companies.
- Best for straightforward projects A specialist householder planning and drawing service can often manage the survey, plans and application together.
- Best for difficult sites A chartered planning consultant may be valuable where policy, heritage, green-belt or refusal issues arise.
- Permission guarantee No firm can guarantee approval because the local planning authority makes the decision.
- Essential quotation checks Survey, design options, drawings, revisions, submission, case officer contact, council fees and technical-stage work.
- Planning versus construction Planning consent does not remove the need to consider Building Regulations, structural design and other legal requirements.
Need a clear route forward? Ask Plans Made Easy to review your extension proposal.
Official planning and professional directories
For current national guidance and independent professional directories, use the following official resources:
- Planning Portal guidance for house extensions
- GOV.UK guidance on when planning permission is required
- Royal Town Planning Institute professional advice and consultant directory
- RIBA directory of Chartered architectural practices
Choosing the right extension planning specialist
The best firm is not necessarily the cheapest or the largest. Instead, look for a team that understands domestic extensions, explains planning risk honestly and provides a clear route from initial survey to council decision.
For a straightforward house extension, a specialist residential planning and drawing consultancy may provide everything you need under one roof. Where the design is unusually complex or the property is affected by sensitive planning constraints, additional architectural or planning consultancy expertise may be appropriate.
Plans Made Easy helps homeowners understand which permissions and drawings their projects require. Our team can prepare compliant plans, submit applications and guide you through the process without unnecessary jargon or uncertainty.
Ready to move your extension forward?
Plans Made Easy can prepare compliant drawings, manage your submission and guide you from the first idea through to the council’s decision.
Performance Verified ✅
This page meets PME Optimisation Standards — achieving 95+ Desktop and 85+ Mobile PageSpeed benchmarks. Verified on
