House Extension, Loft Conversion and Commercial Build Specialists in London
Constructum Code is a London construction company specialising in three core services: house extensions, loft conversions and commercial builds. We work with homeowners, landlords, architects, interior designers and business clients across South East London, Greater London and surrounding areas.
Our registered office is in Loughton, Essex. From there, we manage residential and commercial construction projects across London through one coordinated delivery team — from the first site assessment to final handover.
Our three core construction services
Constructum Code focuses on projects where structural work, planning coordination, construction management and clear communication need to work together. Our primary specialisms are house extensions, loft conversions and commercial builds.
House extensions in South East and Greater London
We design and build side-return, rear and double-storey house extensions for homeowners who need more usable living space without moving. Depending on the property and project scope, an extension may create a larger kitchen, open-plan family area, additional bedroom, home office or improved connection to the garden.
Our team coordinates the project from site assessment and structural input through construction, weatherproofing, internal works and handover. We also work with architects and designers where a project requires specialist design input.
Loft conversions in London
A loft conversion can turn underused roof space into a practical bedroom, home office, guest room or principal suite. Constructum Code delivers dormer, Mansard and roof-light loft conversions, subject to the property structure, planning requirements and building control conditions.
We coordinate structural works, roof alterations, insulation, fire-safety considerations, windows, plumbing, electrical works, plastering, joinery and final finishing within the agreed scope of works.
Commercial builds, fit-outs and refurbishments
We deliver commercial construction work for offices, retail units and business premises. Our commercial scope can include structural fit-outs, internal alterations, refurbishment, partitioning, finishes, engineering coordination and practical improvements designed around how the space will be used.
We work with business owners, commercial landlords, designers and project stakeholders to plan construction activity around the operational requirements of each site.
Borough Planning Portals and Local Policies
Each local authority (such as Southwark, Lambeth, Wandsworth, Lewisham, or Bromley) applies distinct Supplementary Planning Documents (SPDs) and local validation checklists via its planning portal. Local guidance imposes strict rules regarding extension depths, boundary setbacks, daylight and sunlight loss, overshadowing of neighbouring properties (such as the 45-degree rule), and sustainable surface water drainage requirements.
Victorian and Edwardian Architectural Nuances
South London’s predominant housing stock consists of solid-brick Victorian terraces and Edwardian villas, characterised by original lime mortar, shallow corbelled foundations, and rear outrigger projections. Common projects such as side-return kitchen extensions and L-shaped dormer loft conversions require complex structural steelwork, careful underpinning, party wall awards under the Party Wall etc. Act 1996, and vapour-permeable insulation to prevent damp issues.
Conservation Areas and Article 4 Directions
Designated conservation areas frequently carry Article 4 Directions that remove standard Permitted Development rights across specific streets. Exterior alterations visible from the public highway — including replacing original timber sash windows with uPVC, modifying roof profiles, altering brick detailing, or using synthetic slate — require full planning consent and must preserve or enhance the architectural character of the streetscape.
Supporting services for a complete project
Our supporting services are delivered when they are needed to complete one of our three core project types. They are not separate headline specialisms; they form part of a coordinated construction programme.
- Basement conversion and excavation works where a property cannot be extended outward;
- Full or partial property refurbishment connected to an extension, loft conversion or commercial project;
- Structural calculations, steelwork, brickwork, foundations, roof structures and weatherproofing;
- Planning coordination, permitted-development review and party wall process support where relevant;
- Electrical, plumbing, insulation, plastering, joinery, windows and final internal finishes;
- Architectural design, interior design and specialist-trade coordination where required by the project.
A coordinated construction team for each project
Constructum Code manages projects through a coordinated delivery team of skilled construction professionals, specialist trades and project management support. Team capacity is allocated according to the technical requirements, programme and scale of the individual project.
Rather than requiring the client to coordinate separate builders, structural contractors, electricians, plumbers, roofers and finishers independently, we provide one principal point of communication and project coordination within the agreed contractual scope.
This approach is designed to improve continuity between the structural phase, engineering works, internal fit-out and final handover. Responsibilities, programme, scope changes and any additional works are discussed and agreed with the client before they proceed.
Compliance, accreditations and technical coordination
Residential and commercial construction projects in London may require planning permission, permitted-development assessment, party wall procedures, structural design and building control approval. The applicable route depends on the property, location, technical scope and local authority requirements.
Constructum Code works with clients, architects, structural engineers, approved inspectors and local authority planning teams to coordinate the relevant documentation and construction stages. For official guidance, see the UK Government information on Building Regulations approval.
Constructum Code Ltd is listed as a verified firm with TrustMark. The company also states that it holds trade registrations with Certass and FairTrades and is a certified VELUX installation partner for roof-window systems used in loft conversion projects.
Read more about Constructum Code or review our project methodology.
Client feedback and completed work
“Fantastic experience with the Constructum team. We had a side return and extension completed in Clapham, and the job was done brilliantly. Communication with Ben throughout the project was regular and clear.”
“I’m very happy with the loft conversion and kitchen extension Constructum Code completed at my house in Bromley. Ben, the manager, kept good communication and came across as a very fair and honest man.”
How we deliver a house extension, loft conversion or commercial build
Each project differs in design, planning status and technical complexity, but our delivery process follows five connected stages.
- Consultation and site assessment: we discuss your goals, available budget, property conditions, access, site constraints and initial project requirements.
- Planning and technical coordination: we coordinate drawings, structural input, permitted-development assessment or planning applications, party wall processes and other pre-construction requirements where applicable.
- Project scope, programme and pricing: we define the agreed scope of works, construction sequence, material requirements, budget assumptions and delivery programme.
- Structural construction and fit-out: we complete foundations, steelwork, brickwork, roof works, weatherproofing, services, insulation, plastering, joinery and agreed internal finishes.
- Handover and building control completion: we complete the agreed works, prepare relevant handover information and coordinate completion requirements with the relevant building control route.
For further detail, see our full project methodology and the frequently asked questions page.
Registered office, service area and company details
Constructum Code Ltd provides construction services across South East London, Greater London and surrounding areas. Our project locations include East London, South London, Clapham, Bromley, Lewisham, Southwark and neighbouring boroughs, subject to project type, programme and site conditions.
| Legal name | Constructum Code Ltd |
|---|---|
| Company Registration Number | 15031868 |
| VAT Number | 454907667 |
| Registered office | Ground Floor Office, Unit 10a Loughton Business Centre, Langston Road, Loughton, Essex, IG10 3FL, United Kingdom |
| Primary service area | South East London, Greater London and surrounding areas |
| Direct phone | +44 7802 756785 |
| info@constructumcode.co.uk |
Ready to discuss a house extension, loft conversion or commercial build? Contact Constructum Code to request a quote or arrange an initial consultation.
Frequently asked questions
What are Constructum Code’s main services?
Our three main services are house extensions, loft conversions and commercial builds. Basement conversions, refurbishment, planning coordination and specialist trades are supporting services delivered where required for a core construction project.
Do you manage planning permission and building control requirements?
We coordinate relevant planning, technical and building control stages as part of the agreed project scope. The exact process depends on the property, the type of work, local authority rules and whether the project falls under permitted development or requires a planning application.
Do you employ all workers directly?
Projects are delivered through a coordinated team of skilled construction professionals and specialist trades. Team composition is planned according to the technical scope, programme and requirements of each individual project.
