Frequently Asked Questions…

Extensions

  • The cost of a house extension can vary considerably depending on the size, design, specification and complexity of the project. There isn't a single cost that can be applied to every extension, as factors such as the existing property, ground conditions, structural requirements, windows and doors, finishes and internal alterations can all affect the overall cost.

    As a general guide, a single-storey extension will usually cost less than a two-storey extension, while larger or more complex projects will naturally have a higher overall construction cost. A ball park figure of around £2K per M2 for standard extensions/new builds is reasonable, this can however drastically change depending on the design and complexity with some more bespoke builds totalling around £3.5/£4K Per M2

    It is also important to consider the costs beyond the construction work itself. Depending on the project, you may need to allow for architectural fees, planning application fees, building regulations, structural engineering, surveys and other specialist services.

    We recommend establishing a realistic overall budget at the beginning of the project before committing to a design. This allows the proposed extension to be designed with your budget in mind and can help avoid costly changes later.

    At Holmes Architecture & Planning, we can discuss your requirements and provide guidance on the likely scope and costs of your project before progressing with the design.

  • You don't always legally need to appoint an architect to design an extension, but using an experienced architectural professional can make the process considerably easier and help ensure your project is properly designed and documented.

    An architect or architectural designer can help you understand what you can build, whether planning permission is required, how to make the most of your available space and how the proposal can best respond to the existing property.

    They can also prepare the drawings and supporting information required for planning permission and, where required, produce detailed drawings for building regulations.

    Every extension is different, and there can be a surprising amount to consider before you even start building. Planning restrictions, permitted development rights, building regulations, structural requirements, drainage, neighbouring properties and the relationship between the existing and proposed buildings can all influence the design.

    At Holmes Architecture & Planning, we manage the process from the initial design through to planning and building regulations, providing our clients with a single point of contact throughout the process.

  • Potentially, but there are a number of factors that need to be considered before designing an extension directly on or close to a boundary.

    From a planning perspective, the location and height of the proposed extension can affect whether it falls within Permitted Development rights or whether a planning application is required. There may also be specific restrictions relating to the property or its location.

    You also need to consider your neighbour's property and the practical construction of the extension. Building directly against or close to a boundary can have implications for foundations, access, gutters, roof design, maintenance and drainage.

    The Party Wall etc. Act 1996 may also apply depending on the proposed works and the relationship between the extension and neighbouring structures. This is separate from planning permission and building regulations.

    If you're considering building close to a boundary, we can assess the property and proposed extension and advise on the planning and design considerations before you proceed.

  • How far you can extend depends on several factors, including the type of extension, the existing property, previous extensions, its location and whether you're intending to use Permitted Development rights or submit a full planning application.

    For example, there are specific limitations relating to the depth, height and width of extensions under Permitted Development. The rules also differ depending on whether the extension is single-storey or two-storey.

    Previous extensions to the property can also affect what you are able to build, as can restrictions such as a Conservation Area, Article 4 Direction or Listed Building status.

    If you're applying for planning permission, there isn't necessarily a simple maximum distance that applies to every property. The local planning authority will consider the proposal based on the circumstances of the site, the design and its impact on the surrounding area.

    Rather than designing an extension based solely on the maximum dimensions allowed, we recommend considering how much additional space you actually need and how the extension can best work with the existing house and garden.

    We can assess your property and advise on the potential options before developing the design.

  • Yes, a two-storey extension can be possible, although the planning requirements are generally more involved than for a single-storey extension.

    The acceptability of a two-storey extension will depend on factors such as the size and position of the property, the proposed design, its relationship with neighbouring properties, overlooking, loss of light, the character of the area and relevant planning policies.

    Some two-storey extensions may fall within Permitted Development rights if they meet all of the relevant criteria, although there are more restrictions than for many single-storey extensions.

    Where planning permission is required, the design needs to demonstrate that the proposed extension is appropriate for the property and its surroundings.

    A well-designed two-storey extension can provide a significant amount of additional accommodation, potentially creating extra living space at ground floor while also providing additional bedrooms or bathrooms above.

    At Holmes Architecture & Planning, we have experience designing and obtaining planning permission for two-storey extensions across Cambridgeshire and the surrounding areas.

  • In many cases, yes, but the previous extension needs to be taken into account when considering what can be built.

    If the previous extension was constructed under Permitted Development rights, the amount of development already carried out may affect what additional work can be undertaken under the current Permitted Development rules.

    It is therefore important to establish what has previously been built, when it was constructed and whether planning permission or Permitted Development rights were used.

    Even if a property has already been extended, it may still be possible to create additional space through a further extension. However, the most appropriate approach will depend on the property, the existing extension and the planning constraints affecting the site.

    For example, a property that already has a rear extension may still have opportunities for a side extension, first-floor extension or other alterations, subject to the relevant planning requirements.

    We can review the existing property and any previous planning history before advising on what options may be available.

Building Regulation

  • Building Regulations are minimum standards that apply to building work to ensure that buildings are designed and constructed to meet requirements relating to areas such as structural safety, fire safety, energy efficiency, ventilation, drainage, accessibility and health and safety.

    They are separate from planning permission.

    For example, planning permission is primarily concerned with whether a development is acceptable in terms of its design, appearance, use and impact on the surrounding area, whereas Building Regulations are concerned with how the building is constructed and whether it meets the required technical standards.

    Building Regulations can apply even where planning permission isn't required. For example, an extension may be permitted development from a planning perspective but will still need to comply with Building Regulations.

    Depending on the project, Building Regulations approval will normally need to be obtained before or during the construction process.

    At Holmes Architecture & Planning, we can prepare detailed Building Regulations drawings and specifications to help demonstrate how your proposed project will comply with the relevant requirements.

  • Planning permission and Building Regulations are two separate things, and obtaining one does not automatically give you approval for the other.

    Planning permission is primarily concerned with whether the proposed development is acceptable. This can include considerations such as:

    • The appearance and design of the proposal

    • The size and position of the development

    • Its impact on neighbouring properties

    • The character of the area

    • The use of the building

    • The impact on the surrounding environment

    Building Regulations are concerned with how the building will be constructed and whether it meets the required technical standards.

    This can include:

    • Structural stability

    • Fire safety

    • Thermal performance and insulation

    • Ventilation

    • Drainage

    • Electrical safety

    • Accessibility

    • Energy efficiency

    A project may therefore receive planning permission but still require further work before it can be constructed in accordance with Building Regulations.

    For most extension projects, both planning and Building Regulations need to be considered, even though they are separate processes.

  • In most cases, yes. Building Regulations will generally apply to house extensions, regardless of whether planning permission is required.

    This means that an extension which qualifies as Permitted Development from a planning perspective will still need to comply with Building Regulations.

    Building Regulations cover the technical aspects of the construction, including matters such as foundations, structural stability, insulation, fire safety, ventilation and drainage.

    The level of information required will depend on the project. A detailed Building Regulations drawing package can be used to demonstrate how the proposed extension will meet the relevant requirements and can also provide your builder with the information needed to construct the project correctly.

    At Holmes Architecture & Planning, we can prepare the architectural drawings and specifications required for the Building Regulations stage and coordinate with structural engineers and other consultants where necessary.

  • You may need a structural engineer whenever your project involves new or altered structural elements.

    For an extension, this could include:

    • New foundations

    • Steel beams

    • Removing load-bearing walls

    • Large openings in existing walls

    • New roof structures

    • Changes to the existing roof

    • Structural alterations to the existing building

    • Significant changes to floors or walls

    A structural engineer will assess the proposed design and provide the necessary structural calculations and details to demonstrate that the building will be structurally safe.

    The requirement for a structural engineer can vary considerably between projects. A relatively straightforward extension may require calculations for foundations and beams, while a more complex project could require considerably more structural design.

    We will identify where structural engineering is required as part of the design process and can coordinate with a structural engineer to ensure that the structural information works alongside the architectural drawings.

    It's important to remember that architectural and structural drawings serve different purposes. We prepare the architectural design and drawings, while the structural engineer is responsible for the structural calculations and design of structural elements.

Planning Permission

  • Not necessarily. Whether you need planning permission will depend on the size and design of the proposed extension, the property and its location, as well as any previous extensions or alterations that have been carried out.

    Some extensions can be built under Permitted Development (PD) rights, meaning a formal planning application may not be required, provided the proposal meets all of the relevant requirements.

    For example, there are limits relating to the height, depth and position of an extension, and different rules can apply to single-storey and two-storey extensions.

    It's also important to establish whether there are any restrictions on the property. Conservation Areas, Listed Buildings, Article 4 Directions and other planning constraints can affect whether Permitted Development rights are available.

    If you're unsure whether your proposed extension requires planning permission, we can review your property and proposed works and advise on the most appropriate route before you proceed with the design.

  • The time required to obtain planning permission can vary depending on the type and complexity of the application and whether any issues arise during the process.

    For a typical householder planning application, the council will generally aim to make a decision within 8 weeks from the point the application is validated.

    However, the overall process can take longer than this. Before an application can be submitted, time is usually required to carry out a measured survey, prepare the proposed designs and drawings, and put together the necessary planning documentation.

    Once submitted, the planning authority may also request amendments or additional information, or require an extension of time to reach a decision.

    For this reason, we recommend allowing several months from the initial design stage through to receiving a planning decision, rather than simply allowing eight weeks for the application itself.

    We manage the planning process on behalf of our clients and keep them informed throughout the application.

  • The cost of planning permission consists of more than just the planning application fee.

    For a house extension, you will generally have costs associated with preparing the architectural drawings and planning documentation, as well as the planning application fee payable to the local authority.

    The overall cost will depend on the size and complexity of your project. A straightforward single-storey extension will typically require less work than a larger two-storey extension, a new-build property or a proposal involving more complex planning considerations.

    There may also be additional costs depending on the project, such as a measured survey, structural engineer, specialist reports or other supporting information.

    At Holmes Architecture & Planning, we provide a clear, fixed-fee quotation at the beginning of every project, so you know exactly what is included and what you can expect to pay from the outset.

    Our fees vary depending on the size, complexity and requirements of each project. As a general guide, our planning drawing packages typically range from around £495 for smaller projects, such as porch extensions, to approximately £1,895 for larger two-storey extensions. For new-build projects, planning drawing packages typically start from around £2,495.

    Our planning drawing packages can include detailed architectural drawings, specifications and 3D visuals, helping you to clearly understand and present your proposed development. If required, additional services such as photorealistic 3D models and animations can also be provided at an additional cost.

    We don't offer a standard "off-the-shelf" price because every project is different. Instead, we review each enquiry individually, discuss your requirements and establish the work involved before providing a quotation.

    Once we have agreed the scope of work, we provide a fixed fee upfront, giving you certainty over the cost of our services. Our fees won't change unless the project brief or scope of work changes.

    We also allow for a reasonable number of design revisions within our fee proposals. If the Local Planning Authority requests reasonable amendments to the drawings during the planning application process, these changes are also covered within our agreed fee.

    We believe that providing a clear fixed fee from the outset gives our clients peace of mind and confidence that their architectural costs won't unexpectedly increase throughout the project.

    This approach has worked extremely well for our current and previous clients, and we believe it provides a straightforward and transparent way of working from the very beginning.

  • A refusal of planning permission doesn't necessarily mean that your project cannot go ahead.

    When an application is refused, the planning authority will provide reasons explaining why the proposal was considered unacceptable. These reasons should be carefully reviewed before deciding what to do next.

    Depending on the circumstances, it may be possible to amend the design and submit a revised application addressing the reasons for refusal. In many cases, this can be the most straightforward approach.

    There is also the option to appeal the planning decision, although whether an appeal is appropriate will depend on the circumstances and the reasons for refusal.

    Our approach is to understand the planning authority's concerns and work with our clients to determine the most appropriate way forward. Where possible, we will identify potential planning issues during the design stage to reduce the risk of problems later in the process.

  • A planning condition is a requirement attached to a planning permission that must be complied with as part of the approval.

    Planning permission isn't always simply a case of receiving an approval and being able to start building immediately. The council may impose conditions relating to things such as materials, landscaping, windows, external finishes or other aspects of the development.

    Some conditions need to be dealt with before development can begin, while others may need to be complied with during or after construction.

    For example, a planning permission might require details of the proposed external materials to be submitted and approved before work starts.

    It's important to understand the conditions attached to your planning permission before commencing work. Failing to comply with a planning condition can potentially result in enforcement action.

    Where conditions are attached to an application we have prepared, we can advise our clients on the requirements and assist with the submission of any necessary information or applications to discharge the conditions.

  • Permitted Development (PD) rights allow certain types of building work and alterations to be carried out without the need to submit a full planning application.

    There are specific rules and limitations that must be followed. For residential properties, these can cover works such as certain extensions, loft conversions, outbuildings and other alterations.

    Just because a project appears to fall within Permitted Development doesn't necessarily mean that planning permission isn't required. The proposal must meet all of the relevant criteria.

    There can also be restrictions on Permitted Development rights depending on the property and its location. For example, Listed Buildings, properties within Conservation Areas and homes affected by an Article 4 Direction may have additional restrictions.

    If your proposed works fall within Permitted Development, you may also wish to apply for a Lawful Development Certificate. This provides formal confirmation from the local authority that the proposed or existing works are lawful under planning legislation.

    We can review your proposed project and advise whether it is likely to fall within Permitted Development or whether a full planning application is required.

  • Holmes Architecture & Planning is based in Soham, Cambridgeshire, providing architectural design and planning services throughout East Cambridgeshire and the surrounding areas.

    Our location in Soham allows us to work with homeowners, developers and businesses across a wide area, including Soham, Ely, Isleham, Fordham, Newmarket, Burwell, Swaffham Prior, Cambridge and Bury St Edmunds, as well as many of the surrounding villages and towns.

    We have extensive experience working on projects throughout the region, including single-storey and two-storey extensions, loft conversions, new-build homes, residential developments and planning applications. Our portfolio includes projects in many of the areas we cover, giving us valuable local experience and an understanding of the different planning considerations that can affect properties across Cambridgeshire and Suffolk.

    Although we are based in Soham, we regularly work with clients further afield and don't limit our services to a specific radius. If you're unsure whether we cover your area, please get in touch and we'd be happy to discuss your project.

    Looking for an architectural designer in your area? Browse our portfolio below to see examples of projects we've completed in Soham, Ely, Newmarket, Cambridge, Burwell, Fordham, Swaffham Prior and surrounding areas.

    View our portfolio →

    Areas we regularly work in:

Architectural Drawings

  • The drawings you need will depend on the type and complexity of your project and what you are applying for.

    For a typical house extension, a planning application will generally require drawings showing the existing property and the proposed changes. These can include existing and proposed floor plans, elevations and site/location plans, along with other information where required.

    For more complex projects, additional drawings and information may be necessary to properly explain the proposal. This could include sections through the building, roof plans, site plans, details of materials, 3D Visuals and other supporting information.

    If the project progresses to Building Regulations, the drawings need to become considerably more detailed. They will need to demonstrate how the proposed building work will meet the relevant Building Regulations requirements. These drawings may include construction details, insulation specifications, structural information, drainage and other technical details.

    At Holmes Architecture & Planning, we establish what drawings and information are required for your particular project and provide a drawing package appropriate to the stage of the project.

  • The cost of architectural drawings depends on the size, complexity and requirements of the project. A small and straightforward project will require considerably less work than a large extension, new build or more complex alteration.

    At Holmes Architecture & Planning, our typical planning drawing packages start from around £495 for smaller projects, such as porch extensions, and are around £1,895 for larger two-storey extensions. New-build planning drawing packages typically start from around £2,495.

    Our planning drawing packages can include detailed architectural drawings, specifications and 3D visuals, depending on the requirements of the project.

    Additional services, such as photorealistic 3D models and animations, can also be provided where required.

    We don't have a standard price for every type of project because every property and brief is different. We review each enquiry individually and establish the work involved before providing a fixed-fee quotation.

    Our quotation sets out exactly what is included, and our fees will not change unless the agreed scope or brief changes. We also allow for a reasonable number of design revisions within our proposals.

    This approach gives our clients certainty over the cost of our services from the outset, without having to worry about fees unexpectedly increasing as the project progresses.

  • In most cases, yes, an accurate survey of the existing property is required before detailed architectural drawings can be prepared.

    A measured survey records the existing building, including its dimensions, room layouts, floor levels, windows, doors and other relevant features. Depending on the project, external features such as boundaries, neighbouring buildings and levels may also need to be recorded.

    Having accurate information about the existing property is particularly important when designing an extension or alteration. The proposed drawings need to accurately reflect what is currently there so that the new design can be properly coordinated.

    For some smaller or straightforward projects, it may be possible to use existing information or undertake a more limited survey, depending on the circumstances.

    We can advise you on what level of survey is appropriate for your project before work begins.

    It's worth remembering that the survey and the architectural design are two separate parts of the process. The survey establishes an accurate record of the existing property, while we use that information to develop and prepare the proposed design.

  • Structural drawings are generally required when the proposed works involve structural alterations to the existing building or new structural elements.

    For example, an extension may require structural calculations and drawings for foundations, steel beams, roof structures or other elements that need to support the building.

    Structural design is normally undertaken by a structural engineer, who will assess the proposed design and calculate the appropriate structural requirements.

    The exact information required will depend on the project. A simple internal alteration may require relatively limited structural information, whereas a large extension or more significant alteration may require detailed structural calculations and drawings.

    At Holmes Architecture & Planning, we can coordinate with a structural engineer where one is required and incorporate the relevant structural information into the architectural and Building Regulations package. We work with several local companies and can provide recommendations on request.

  • Yes, absolutely! We often receive projects from clients that were originally started by other Architects or Designers.

    We can produce the next Building Regulation stage of drawings, Discharge the Planning Conditions or submit a new Planning Application if required.