A
Approved Document
An Approved Document is a piece of statutory guidance published by the UK government that shows one way to comply with the Building Regulations in England and Wales. There are Approved Documents covering structure (Part A), fire safety (Part B), ventilation (Part F), energy efficiency (Part L), and many others. They are not the only way to comply, but following them is the simplest route to demonstrating compliance during a building regulations application.
Approved Inspector
An Approved Inspector is a private-sector body authorised to carry out building control functions as an alternative to your local authority building control (LABC) service. Approved Inspectors check that your building work complies with the Building Regulations and issue a Final Certificate on completion. Homeowners in London can choose either an Approved Inspector or their borough council for building control — the legal effect is the same.
Article 4 Direction
An Article 4 Direction is a legal order made by a local planning authority that removes specific Permitted Development rights in a defined area. In London, Article 4 Directions are widespread — many boroughs use them in conservation areas or entire wards to require full planning permission for work that would otherwise be permitted, such as loft conversions, changes to front elevations, or alterations to windows and doors. Always check whether an Article 4 Direction applies to your property before assuming you can build under PD rights.
Read our full guide to planning permission in London →Architectural Technologist
An architectural technologist is a construction professional who specialises in the technical design, detailing, and regulatory aspects of buildings. Unlike architects, who focus on concept and design, architectural technologists focus on making designs buildable, code-compliant, and cost-effective. In the UK, chartered architectural technologists hold MCIAT status through the Chartered Institute of Architectural Technologists (CIAT). At Architectural Drawings London, our MCIAT chartered team prepares planning and building regulations drawings at fees 30% below typical London architect rates.
Meet our chartered team →B
Block Plan
A block plan (also called a 1:500 site plan) is a drawing that shows the development site in relation to surrounding properties and streets. It is typically drawn at 1:500 scale and is a required document for most planning applications in London. The block plan must show the property boundaries, the outline of existing and proposed buildings, access roads, and the site's relationship to neighbouring structures. It is different from a site location plan, which is drawn at 1:1250 scale and covers a wider area.
Boundary Treatment
Boundary treatment refers to the physical structures that define the edges of a property, including fences, walls, hedges, and railings. In a planning application, you may be asked to provide a boundary treatment plan showing existing and proposed boundaries, especially if your extension or new building is close to a neighbour. In conservation areas, changes to boundary treatments facing the highway may themselves require planning permission.
Building Control
Building control is the process of checking that building work complies with the Building Regulations. In England, building control is carried out either by your local authority building control department (LABC) or by a private Approved Inspector. Building control involves plan checking before work starts and site inspections during construction. A Completion Certificate is issued when the work is signed off. Building control is separate from planning permission — you typically need both for any significant building project.
Building Regulations
Building regulations are the minimum standards for the design, construction, and alteration of buildings in England and Wales. They cover structural safety (Part A), fire safety (Part B), resistance to moisture (Part C), drainage (Part H), energy efficiency (Part L), ventilation (Part F), and accessibility (Part M), among others. Nearly all building work — including extensions, loft conversions, and structural alterations — needs building regulations approval. Compliance is demonstrated through detailed technical drawings and specifications reviewed by building control.
Our building regulations drawings service →Build Over Agreement
A Build Over Agreement is a formal consent from your local water authority (Thames Water in most of London) that allows you to build over or near a public sewer. If your proposed extension or new foundation is within 3 metres of a public sewer, you will need a Build Over Agreement before work can start. The water authority will review your structural drawings to ensure the sewer is protected during and after construction. Failing to obtain one can result in enforcement action and complications when selling the property.
C
CIL (Community Infrastructure Levy)
The Community Infrastructure Levy (CIL) is a charge that local planning authorities in London can impose on new development to help fund infrastructure such as schools, transport, and healthcare. CIL is calculated per square metre of new floor space and varies by borough — rates in central London boroughs are significantly higher than in outer boroughs. Residential extensions and loft conversions may be exempt from CIL if the total new floor area is under 100 square metres, but you must submit a CIL exemption form with your planning application.
Completion Certificate
A Completion Certificate (also called a Final Certificate when issued by an Approved Inspector) is the official document confirming that building work has been inspected and complies with the Building Regulations. It is issued by either local authority building control or an Approved Inspector after final inspection. A Completion Certificate is essential when selling a property — without it, buyers' solicitors and mortgage lenders will flag the work as potentially non-compliant.
Conservation Area
A conservation area is a neighbourhood or district designated by the local planning authority as having special architectural or historic interest whose character or appearance is worth preserving or enhancing. In London, there are over 1,000 conservation areas across the 33 boroughs. Properties in conservation areas face stricter planning rules: Permitted Development rights are reduced, front-elevation changes typically need permission, and demolition may require Conservation Area Consent. If your property is in a conservation area, we recommend checking restrictions before planning any work.
Planning permission in conservation areas →Condition (Planning)
A planning condition is a requirement attached to a planning permission that must be met before, during, or after development. Common conditions include requiring specific materials to be approved before construction begins, limiting construction hours, requiring landscaping to be completed within a certain timeframe, or restricting the use of the property. Conditions are legally binding — failure to comply can result in enforcement action. Your planning approval letter will list all conditions, and some (called pre-commencement conditions) must be formally discharged before any building work starts.
D
Design & Access Statement
A Design & Access Statement (DAS) is a supporting document submitted with certain planning applications that explains the design principles behind the proposal, how it responds to the local context, and how access and movement through the site have been considered. In London, a DAS is required for major applications and for applications affecting listed buildings. It is not required for standard householder applications, but some boroughs recommend submitting one to strengthen your case.
Dormer
A dormer is a structural extension that projects vertically from the slope of a roof, creating usable space and headroom in a loft conversion. There are several types: flat-roof dormers (the most common in London), gabled dormers, hipped dormers, and shed dormers. Under Permitted Development, rear dormers may be built without planning permission, subject to volume limits, but any dormer facing the highway always requires planning permission. Dormer design is a critical part of loft conversion drawings.
Loft conversion drawings →Dwelling
In planning and building regulations terms, a dwelling is a self-contained unit of residential accommodation. A dwelling must have its own front door, kitchen, bathroom, and sleeping area. The distinction matters because the creation of a new dwelling (such as subdividing a house into flats, or building a new house on garden land) almost always requires full planning permission, whereas alterations to an existing dwelling may fall under Permitted Development.
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Eaves
The eaves are the lower edges of a roof where it overhangs the external wall of a building. Eaves height is an important measurement in planning terms because Permitted Development rules specify that extensions and outbuildings must not exceed the height of the eaves of the original house. Eaves height is measured from ground level to the point where the external wall meets the underside of the roof slope.
Elevation (Drawing)
An elevation drawing is a scaled, two-dimensional drawing showing the external face of a building as viewed from one side — front elevation, rear elevation, or side elevations. Elevation drawings are required for both planning and building regulations applications. They show the proposed materials, window positions, roof lines, ridge and eaves heights, and the relationship of the building to ground levels and neighbouring properties.
Our planning drawings service →Extension
An extension is an addition to an existing building that increases its floor area. Common types in London residential projects include single-storey rear extensions, double-storey rear extensions, side return extensions, wrap-around extensions, and over-structure extensions. Whether an extension needs planning permission depends on its size, position, and relationship to the boundaries, as well as whether the property is in a conservation area or subject to an Article 4 Direction.
House extension drawings →F
FAR (Floor Area Ratio)
Floor Area Ratio (FAR), sometimes called plot ratio, is the total floor area of a building divided by the total area of the site. Some London boroughs use plot ratio limits in their local plans to control the bulk and density of development. A high FAR means the building takes up a large proportion of the site. Understanding FAR is important when designing extensions or new builds because exceeding the borough's plot ratio policy may be grounds for refusal of planning permission.
Fire Strategy
A fire strategy is a document (and set of drawings) that demonstrates how a building achieves fire safety compliance under Building Regulations Part B. For residential projects, a fire strategy covers means of escape (escape routes, protected stairways, fire doors), fire detection and alarm systems, fire separation between compartments, and external fire spread. A fire strategy is particularly critical in loft conversions, where the new room is typically three storeys above ground level and requires a protected escape route.
Flue Regulations
Flue regulations govern the installation and positioning of boiler flues, chimney flues, and extraction systems under Building Regulations Part J. If your extension or loft conversion involves repositioning a boiler or installing a new heating system, the flue must comply with minimum distance requirements from windows, boundaries, and neighbouring openings. Incorrectly positioned flues are a common reason for building control rejections in London residential projects.
Full Planning Application
A full planning application (also called a householder application when it involves a single dwelling) is the standard route for seeking planning permission. It requires a completed application form, scaled drawings (site plan, floor plans, elevations), a Design & Access Statement (if applicable), and the statutory fee. The determination period is 8 weeks for householder applications and 13 weeks for major applications. The council assesses the proposal against its Local Plan, the London Plan, and the National Planning Policy Framework.
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Garage Conversion
A garage conversion is the process of converting an existing integral or attached garage into habitable living space, such as a bedroom, home office, or living room. In many cases, a garage conversion does not need planning permission because it is classified as an internal alteration. However, it will need building regulations approval to ensure the converted space meets thermal insulation, ventilation, damp-proofing, and fire safety standards. If the garage is detached or in a conservation area, planning rules may differ.
Glazing Ratio
Glazing ratio refers to the proportion of glazed area (windows and doors) relative to the total floor area of a room or building. Under Building Regulations Part L (energy efficiency), there are limits on the total area of glazing in new extensions and conversions to prevent excessive heat loss. However, larger windows may be acceptable if they use high-performance glazing with a low U-value. Your building regulations drawings must demonstrate that the glazing ratio and specification meet the energy performance targets.
Ground Floor Plan
A ground floor plan is a scaled architectural drawing showing the layout of a building at ground level, viewed from above. It shows internal walls, doors, windows, staircases, kitchens, bathrooms, and dimensions. Ground floor plans are required for both planning permission and building regulations applications. The drawings must show the existing layout and the proposed layout, so the council and building control can understand exactly what is changing.
H
Heritage Statement
A Heritage Statement is a supporting document required for planning applications that affect a listed building, a building in a conservation area, or a site near a scheduled monument. It describes the significance of the heritage asset and explains how the proposed development has been designed to preserve or enhance that significance. In London, many boroughs require a Heritage Statement for any visible alteration in a conservation area, not just work to listed buildings.
Hip-to-Gable
A hip-to-gable conversion is a type of loft conversion where the sloping (hipped) side of a roof is extended outward to form a vertical (gable) wall, creating additional headroom and floor space. This is one of the most common loft conversion approaches for semi-detached and detached houses in London. Under Permitted Development, a hip-to-gable alteration is usually permitted at the rear, but a hip-to-gable on the front or side facing a highway will require planning permission.
Loft conversion drawings →Householder Application
A householder application is the specific type of planning application for alterations and extensions to a single dwelling house. It is the most common planning application type in London. The statutory fee is £258 (2026 rate), and the council has 8 weeks to make a decision. Householder applications cover extensions, loft conversions, dormers, outbuildings, and changes to the external appearance of a house. If your property is a flat or you are creating a new dwelling, a different application type is required.
HMO (House in Multiple Occupation)
An HMO (House in Multiple Occupation) is a property rented out by at least three tenants who are not from the same household and who share facilities such as a kitchen or bathroom. Converting a house to an HMO is a material change of use that may require planning permission, depending on the number of occupants and the borough's policies. Large HMOs (7 or more tenants) always require planning permission. HMOs also have specific building regulations requirements for fire safety, room sizes, and amenities.
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LABC (Local Authority Building Control)
LABC stands for Local Authority Building Control, which is the building control service provided by your local council (borough council in London). LABC checks that proposed building work complies with the Building Regulations, carries out site inspections during construction, and issues Completion Certificates when the work is signed off. You can use LABC or a private Approved Inspector — the choice is yours.
Lawful Development Certificate (LDC)
A Lawful Development Certificate (LDC) is a formal legal document from your local planning authority confirming that a proposed or existing development is lawful and does not require planning permission. There are two types: a “proposed” LDC (for work you plan to do) costing £129, and an “existing” LDC (for work already completed) costing £258. We strongly recommend obtaining an LDC for any Permitted Development project, as it provides legal certainty and protects you when selling the property. Without it, buyers' solicitors and mortgage lenders may raise queries about the legality of the work.
Listed Building
A listed building is a structure of special architectural or historic interest that has been placed on the Statutory List of Buildings by Historic England. There are three grades: Grade I (exceptional interest), Grade II* (particularly important), and Grade II (special interest). Any alteration to a listed building — internal or external — that affects its character requires Listed Building Consent, which is a separate application from planning permission. Unauthorised work to a listed building is a criminal offence.
Loft Conversion
A loft conversion is the process of transforming an unused roof space (attic) into a habitable room such as a bedroom, home office, or bathroom. Common types include rear dormer conversions, hip-to-gable conversions, mansard conversions, and roof-light (Velux) conversions. In London, many loft conversions fall under Permitted Development, but Article 4 Directions, conservation areas, and flats are excluded. All loft conversions require building regulations approval for structural, fire safety, and thermal performance compliance.
Loft conversion drawings →M
Mansard
A mansard is a type of roof or roof extension where the lower slope is nearly vertical and the upper slope is nearly flat, creating maximum usable floor space within the roof structure. Mansard conversions are the preferred choice for terraced houses in many London boroughs because they add a full-height storey. Unlike other loft conversions, mansard extensions always require planning permission because they fundamentally alter the roof profile and building height.
Mansard roof extension drawings →Material Change of Use
A material change of use occurs when a building or land is used for a different purpose in a way that is significant in planning terms. Examples include converting a house into flats, turning a shop into a restaurant, or changing a dwelling into an HMO. Most material changes of use require planning permission, though some are permitted under the Use Classes Order or through Prior Approval routes. Changes of use may also trigger building regulations requirements.
MCIAT (Member of CIAT)
MCIAT stands for Member of the Chartered Institute of Architectural Technologists. It is the professional designation for chartered architectural technologists in the UK. MCIAT members have met rigorous academic and professional practice requirements, are bound by a code of conduct, and carry professional indemnity insurance. At Architectural Drawings London, our team holds MCIAT chartered status, ensuring your planning drawings and building regulations submissions are prepared to the highest professional standard.
About our MCIAT chartered team →Measured Survey
A measured survey is a precise, scaled record of an existing building, drawn from physical measurements taken on site. It includes floor plans, elevations, section drawings, and dimensions. A measured survey forms the baseline for any architectural design work, because the proposed drawings need to show the existing building accurately alongside the proposed changes. Most London projects start with a measured survey — without one, the drawings submitted for planning or building regulations may be inaccurate and risk rejection or costly amendments.
O
Outline Planning Permission
Outline planning permission is a type of planning consent that establishes the principle of development on a site without going into full detail. It is typically used for larger projects such as new-build houses or subdivision of plots. If outline permission is granted, the applicant must then submit a Reserved Matters application dealing with the detailed design before work can begin. Outline applications are uncommon for typical householder projects in London, where a full planning application is the standard route.
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Party Wall Act 1996
The Party Wall etc. Act 1996 is a piece of UK legislation that sets out the rights and obligations of building owners who wish to carry out work on or near a shared wall, boundary, or excavation close to a neighbouring property. If your extension, loft conversion, or basement project involves building on or within certain distances of a party wall or boundary, you must serve formal notice on your neighbours. If they do not consent, a Party Wall Award must be prepared by a surveyor. The Act is separate from both planning permission and building regulations — you need to comply with all three.
Permitted Development
Permitted Development (PD) is the legal right to carry out certain types of building work without needing to apply for planning permission, subject to specific limits and conditions set out in the General Permitted Development Order (GPDO). In London, PD rights cover many common improvements including single-storey rear extensions (up to 6m for terraced/semi, 8m for detached via Prior Approval), loft conversions within volume limits, and outbuildings. However, PD rights can be removed by Article 4 Directions, conservation area designations, or conditions on the original planning permission.
When do you need planning permission in London? →Planning Condition
See Condition (Planning) above.
Planning Drawing
A planning drawing is a scaled architectural drawing submitted as part of a planning application. The minimum set typically includes a site location plan (1:1250), a block plan (1:500), existing and proposed floor plans (1:50 or 1:100), and existing and proposed elevations (1:50 or 1:100). All drawings must be accurate, to scale, and clearly annotated. At Architectural Drawings London, our MCIAT chartered team prepares planning drawings from £840 (Essentials) to £1,750 (Complete).
Planning drawings service →Planning Permission
Planning permission is formal consent from your local planning authority to carry out building work, change the use of a building, or alter land. In London, the local planning authority is your borough council. The planning system exists to ensure development is appropriate for the area, respects the streetscape, protects neighbouring properties, and complies with local, regional (London Plan), and national planning policy. Applications are typically determined within 8 weeks for householder applications and 13 weeks for major applications.
Complete guide to planning permission in London →Planning Portal
The Planning Portal is the UK government's online platform for submitting planning applications, building control notifications, and related documents. Most planning applications in London are submitted through the Planning Portal, which routes them to the relevant borough council. The Portal also provides guidance on Permitted Development rights, application fees, and required documents. You can check whether your property is in a conservation area or affected by an Article 4 Direction using the interactive map on your borough's planning pages.
Prior Approval
Prior Approval is a lighter-touch application process for certain types of development that fall under Permitted Development but where the council has the right to assess specific impacts before work begins. For example, single-storey rear extensions between 6m and 8m on detached houses require Prior Approval — the council notifies neighbours and assesses the impact on their amenity. Prior Approval is also used for office-to-residential conversions, agricultural-to-residential conversions, and some telecommunications installations. The fee is lower than a full planning application.
Prior Notification
Prior Notification is similar to Prior Approval but applies to a different set of development types under the GPDO, including demolition of buildings and certain agricultural or forestry buildings. The applicant notifies the council of the proposed work, and the council has 28 days to decide whether Prior Approval is required. If the council does not respond within 28 days, the work can proceed. Prior Notification is less common in residential London projects but may apply to some commercial-to-residential conversions.
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Rear Dormer
A rear dormer is a dormer extension built on the rear roof slope of a property, facing away from the street. In London, rear dormers are the most common form of loft extension because they maximise usable headroom. Under Permitted Development, rear dormers can often be built without planning permission, subject to volume limits (40 cubic metres for terraced/semi-detached, 50 cubic metres for detached) and certain design restrictions. However, properties in conservation areas or subject to Article 4 Directions will typically need planning permission.
Reserved Matters
Reserved Matters are the detailed design aspects of a development that are deferred from an Outline Planning Permission and must be approved separately before construction can begin. The five reserved matters are: access, appearance, landscaping, layout, and scale. A Reserved Matters application must be submitted within the time limit specified in the outline permission (typically 3 years). This process is mainly used for larger developments and is uncommon for standard London householder projects.
Revit
Revit is a Building Information Modelling (BIM) software developed by Autodesk. It is used by architects and architectural technologists to create detailed 3D models and produce construction drawings, schedules, and coordination documents. Revit models contain intelligent building data (materials, dimensions, structural properties), making them more powerful than traditional 2D CAD drawings. At Architectural Drawings London, we use Revit and AutoCAD to produce precise, compliant drawings for planning and building regulations submissions.
Ridge Height
The ridge height is the highest point of a pitched roof, measured from ground level to the top of the ridge line. Ridge height is a key measurement in planning assessments because Permitted Development rules typically state that extensions and loft conversions must not exceed the ridge height of the original house. Planning officers also assess ridge height when considering the visual impact of a proposal on the streetscape and neighbouring properties.
Roof Plan
A roof plan is a scaled drawing showing the building from directly above, depicting the shape, pitch, and configuration of the roof, including ridge lines, hip lines, valleys, gutters, and any roof-mounted features like skylights, chimneys, and solar panels. Roof plans are often required for planning applications involving loft conversions, mansard extensions, or any alteration that changes the roofscape. They help planning officers assess the impact of the proposal from above and from neighbouring higher-level windows.
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SAP Assessment
A SAP (Standard Assessment Procedure) assessment is the UK government's method for measuring and comparing the energy performance of dwellings. A SAP assessment calculates a property's energy use, carbon emissions, and fuel costs based on the building fabric, heating system, ventilation, and renewable energy sources. New dwellings and some major extensions require a SAP assessment to demonstrate compliance with Building Regulations Part L (conservation of fuel and power). The result is expressed as a SAP rating between 1 and 100.
Section 106
A Section 106 agreement (also called a planning obligation or s106) is a legal agreement between a developer and the local planning authority, negotiated as part of the planning permission process. Section 106 obligations are used to mitigate the impact of large developments — for example, requiring affordable housing, contributions to local infrastructure, or public open space. Section 106 is typically relevant to major developments rather than standard householder applications in London.
Section Plan
A section plan (or section drawing) is a scaled drawing that shows a building as if it has been cut vertically through a specific plane, revealing the internal structure, floor-to-ceiling heights, wall thicknesses, floor construction, and roof structure. Section drawings are essential for building regulations submissions because they demonstrate structural details, insulation layers, fire compartmentation, and ventilation routes. They are sometimes also requested for planning applications involving complex level changes or basement works.
Side Return Extension
A side return extension is a single-storey extension that fills in the narrow passageway (side return) alongside a terraced or semi-detached house, typically on Victorian and Edwardian properties in London. Side return extensions are one of the most popular home improvements in London because they can dramatically increase kitchen and living space. Under Permitted Development, a side return extension may not need planning permission if it is single-storey, within 3 metres of the boundary, and under 4 metres high — but always check for Article 4 Directions.
House extension drawings →Site Location Plan
A site location plan is a map-based drawing at 1:1250 or 1:2500 scale showing the location of the development site within the wider area. It is a mandatory requirement for all planning applications. The site must be outlined in red (the application site) and any adjoining land owned by the applicant must be outlined in blue. Site location plans are typically based on Ordnance Survey mapping and can be purchased from licensed providers.
Structural Calculations
Structural calculations (also called structural engineering calculations) are mathematical analyses prepared by a structural engineer that demonstrate the proposed construction will safely support all imposed loads, including its own weight, the weight of occupants and furniture (live loads), wind loads, and snow loads. Structural calculations are required for building regulations approval of extensions, loft conversions, the removal of load-bearing walls, and any work involving new foundations, steel beams, or structural alterations. They complement the architectural drawings prepared by our team.
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Topographic Survey
A topographic survey is a survey that records the physical features and levels of a site, including ground contours, drainage covers, trees, fences, road levels, and the positions of neighbouring buildings. It is typically required for projects on sloping sites, basement conversions, or developments where the relationship between ground levels and the proposed building is critical. A topographic survey provides the accurate site data needed to design appropriate foundations and drainage.
Tree Protection Order (TPO)
A Tree Protection Order (TPO) is a legal order made by the local planning authority to protect specific trees or areas of woodland. It is an offence to cut down, top, lop, uproot, or wilfully damage a tree protected by a TPO without the consent of the council. If your extension, loft conversion, or new building work affects trees protected by a TPO, you must apply for consent before any work (including root zone excavation) takes place. In conservation areas, all trees with a trunk diameter of 75mm or more are automatically protected, and you must give 6 weeks' notice before carrying out any work to them.
U
U-Value
A U-value is a measure of how effectively a building element (wall, roof, floor, window) transmits heat. It is expressed in watts per square metre per degree Kelvin (W/m²K). A lower U-value means better thermal insulation. Building Regulations Part L sets maximum U-values for new construction and extensions — for example, walls in new extensions must typically achieve a U-value of 0.28 W/m²K or better. Your building regulations drawings must specify insulation types and thicknesses that achieve the required U-values.
Use Classes Order
The Use Classes Order is a piece of legislation that categorises the use of land and buildings into defined classes. The main classes include Class C3 (dwelling houses), Class E (commercial, business, and service), and Class F (local community and learning). Changing from one use class to another may constitute a material change of use requiring planning permission. However, some changes between classes are allowed under Permitted Development or Prior Approval, such as certain commercial-to-residential conversions.