London and Hertfordshire, UK

Loft Conversions

Dormer Loft Conversions

Hip to Gable Loft Conversions

L Shaped Loft Conversions

Mansard Loft Conversions


Lccl Construction customers say

4.9 Excellent

4.9 out of 5 based on 128 Reviews

"Excellent architecture services received, Lccl Construction has done a fantastic job with creating the architecture plans"

Review by Jade Morrison

Welcome to Lccl Construction, Loft conversion company, House extension builders, Architectural design services

Your trusted local architecture and construction company in London and Hertfordshire 

Covering London, United Kingdom and Surrounding Areas

Specialist Design and Build Construction Company 

Covering an 85 mile radius from our offices location in Finchley, London.

Architectural design and construction of house extensions. Rear single storey house extensions, side house extensions, wrap around house extensions, side return house extensions, two storey house extensions. We design and build house extensions in London and Hertfordshire.

Architectural design and construction of loft conversions. Dormer loft conversion, hip to gable loft conversions, L-shaped loft conversion, mansard loft conversion or velux loft conversion. We design and build loft conversions in London and Hertfordshire.

Architectural design services for loft conversions, house extensions and new build houses. Complete consultation package London and Hertfordshire, United Kingdom.

We can project manage your project on your behalf, with our construction management services we build loft conversions, home extensions, renovations and new builds.

Find out more about our construction process and stages, how do we go about running our construction project and what are the core elements associated in the construction process.

We can serve party wall notices, serve full party wall awards, liaison with 3rd party surveyors. Our party wall agreement services are conducted by surveyor who is MCIOB and FPWS accredited.

Our structural engineers produce structural design and structural calculations for your loft conversion, home extension, renovation or new build. 

New build scheme solution, we design and build your new house, our solutions of architecture and construction for new build homes, find out more.

Get instant quote for your loft conversion, home extension, upward home extension, renovation or new build including architecture and design build

Types of projects we do including architecture and construction, get your instant design and build quote 


Home extensions

  • Rear home extension

  • Side home extension

  • Side and rear extension

  • Wraparound 

  • Side return 

  • Two storey side

  • Two storey rear

  • Two storey wrap

  • First floor extension

  • Upward extensions


New build 


  • Detached homes

  • Terraced homes

  • Flats

Book consultation call for new build projects.

book consultation call >


Loft conversions


  • Dormer loft conversion

  • Hip to gable loft conversion

  • L shaped loft conversion

  • Mansard loft conversion

  • Velux loft conversion



  • Flat or apartment renovation

  • House renovation

  • Commercial to residential conversion including design and build 

Basement conversion 


  • Full house basement

  • Part house basement 

  • Outrigger basement

Upward extensions 


  • Detached up to two storey upwards

  • Bungalow single storey upwards

  • Terraced single storey upwards

  • Semi detached single storey upwards 


Book consultation call for upward extension projects.

book consultation call >

Get a free instant quote or book a free consultation call


Loft Conversion Design and Build

Lccl Construction unique construction process and design and build process for loft conversion and home extension 

Find out more about Lccl Construction unique construction process or design and build process and what happens on the design or construction stage. 

Step by step explanation of loft conversion, home extension and new build design and construction process. 

We have included our original project images taken on our construction projects.

Lccl construction design and build in London and Hertfordshire, United Kingdom is a specialist loft conversion company, house extension builders, architectural designers and planning company. With our end to end services we successfully start and finish every one of our projects. With our design and build construction company services we can complete all the stages of your build from consultation, architecture, survey to construction including plumbing and electrical installations under one roof. Our combined services includes planning, architectural design and construction. 

By providing services from start to finish we will deal with architecture, planning applications, planning negotiations, building control drawings, building control application, party wall survey and agreements, structural and construction drawings, production of the construction schedule, interior design, construction phase, dealing with building control during construction, electrical and plumbing installations, completion of the construction, certificate and Local Authority Building Control sign off. 

Loft Conversion Company London Limited trading as "Lccl Construction" Registration: 11713461

We cover all areas in London, Hertfordshire, United Kingdom. Our offices are located in 3rd Floor, Hathway House, Popes Drive, Finchley, London N3 1QF. The radius is 85 miles from our office location. Our phone number is: 020 8037 7332

What is a design and build company?

The design and build concept means that multiple specialist skills and trades are combined into one, from start to finish we will deal with all the architecture, consultation, planning and thereafter the entirety of the  construction, saving both time and capital.

We will help you plan, design and build your house extension or loft conversion every step of the way. 


Find out more about successfully completed Lccl Construction design and build projects portfolio click here

House extension builders
- rear and side house extension builders
- wrap around and side return house extension
- two storey house extension builders
- optional LABC 10 year warranty
- plumbing and electrical packages
- design and build company in London
- New permitted development rules applied
Loft conversion company
- dormer and hip to gable loft conversion
- mansard lofts and L shaped loft conversion
- velux loft conversion
- optional LABC 10 year warranty
- plumbing and electrical packages
- design and build loft company london
- new permitted development rules applied
Design and build
- design and build company in London, UK
- design and build of loft conversions
- design and build of house extensions
- design and build new houses
- optional LABC 10 year warranty
- local authority building control partner
- party wall and structural drawings
New build homes
- new home build schemes
- design and construction
- architecture design and planning
- LABC 10 year warranty
- no deposit required
- plumbing and electrical packages
- New permitted development rules applied
Home renovation
- Flat and Apartment Renovations
- House Renovations
- Design and Build
- Plumbing and Electricals
Supply and Install Kitchens, Bathrooms, Flooring, Doors or Wardrobes
Total finishing options
Architecture design services
- Architecture, Design and Planning
- Measured building survey
- Schematic drawings
- Consultation and Party Wall Agreements
- Project Management
- Structural Drawings and Calculations
- Planning and Building Control Application
Show More


measured survey



party wall agreements

lead consultant



structural engineer drawings

Design phase

Construction phase

Your project

Architectural design, survey and construction services under one umbrella

We are your one stop architectural design, survey, project management, construction services company. We take care of everything required for your loft conversion, home extension or renovation project. Meaning we will complete the design phase and construction phase for you, without the need to look anywhere else and you have only one point of contact for everything.

Design phase: 

  • Building measured survey

  • Architecture services

  • Planning application

  • Building control application

  • Party wall agreements 

  • Structural engineers calculations and design

  • Project management

  • Interiors


Construction Phase:

  • Construction of loft conversions and home extensions

  • Project management

  • Logistical supply and coordination

  • Quality control

  • Liaison with building control and inspection

  • Guarantee

Free consultation call

Our totally free consultation call is here to help you talk through ideas, issues and aims for your project with a professional. Why not get online and book a free consultation call and see how we can help you realise your dream home.

Instant quote online

Curious about the cost of your loft conversion, house extension or renovation? With our online quote calculator you can find out anytime of the day or night from the comfort of your own home what the approximate cost of our Architecture services or Design and Build services are. Helping you to make an informed choice about your next steps.

Staggered payments

We do not ask for any large payments up front. Our payments are transparent and divided into reasonable stages. As the work progresses you will make payments relating to the progression of the project. Our payments are broken down into manageable intervals, the payment schedule is produced once you go ahead with our services.

Communication is key

We have created our very own online dashboard. This enables you to easily keep up to date with the progress being made on your project. It also makes it easy for you to get in touch with our team anytime that suits you.

Located in Finchley, London N3

We are local and we cover London and Hertfordshire, this is a major advantage for the smooth running and delivery of your project as we are local to you. We cover an 85 mile radius from our base in Finchley, London N3. We have in-depth knowledge of the London and Hertfordshire area for architecture, survey, loft conversions or home extensions design and build.

Have a building project?

We offer construction services, architectural design services and design & build services combined including:

1. Loft conversions company - (dormer loft conversions, L shape loft conversions, mansard Loft conversions, hip to gable loft conversions or velux loft conversion)

2. House extensions builders - all types (single storey extensions, two storey house extensions, rear and side extensions, side return house extensions, wrap around house extensions, side return single or two storey house extensions)


3. Architectural design and build total project start to finish - design and build of loft conversions, house extensions and new house builds, including M & E and liaising with local planning authority (inc. negotiation, relevant applications and designs) or local authority building control, party wall agreements, administration, project management, interior design and structural/construction drawings.


4. New house builders and residential - we design and carry out construction of new build home projects.

Optional LABC 10 or 12 Year Warranty

We specialise in design and construction of house extensions, loft conversions and new house builds for residential customers.

Featured in media:

Architecture services London, United Kingdom
Loft Conversions Service Locations we Cover
House Extensions Service Locations we Cover
House extensions builders London, United
Knowledge base

Get to know what type of loft conversions and home extensions there are, understand the planning permissions impact of the context.

In short there are 10 stages of the design and build process. Starting with a contact, consultation, quote, full survey, planning permission drawings, building regulation drawings, structural calculation drawings, party wall agreements and construction.


Lccl Construction is one of the  leading construction companies in North London,construction companies in London and construction companies in Hertfordshire, United Kingdom. We are a specialist loft conversion company, house extension builders, design and build company London. With our architecture services, design and build solutions we are able to deliver any type of loft conversion, house extension, both in the London and Hertfordshire areas.

Have a look at the design and build process stages in more detail click here

At Lccl Construction we have carried out many design and build loft conversions and house extension projects in London, Hertfordshire, United Kingdom. We design and build London loft conversions turning them into beautiful spaces. Our aim is to make the process of house extensions or loft conversions as simple as possible, hassle free and stress free for a loft conversion in London and house extension in London.


Some of the customers that live in London and Hertfordshire are looking for extra space due to a growing family or the need for additional space for a home office or some like to invest in their property. Whatever the reason we design and build loft conversions in North London, London and Hertfordshire.

Loft Conversion Company London

1. Contact

You can use our booking form online, on our website to book a consultation call at a time and date that suits you best. Our consultation call is to gain an in-depth understanding of what you would like to achieve or what the project idea is..

4. Full Survey

Building projects that involve home extensions, home renovations and loft conversions will require a full measured survey of the existing property and surrounding site. We can then produce a set of accurate survey drawings using CAD software, which will include plans, elevations and section drawings.

7. Structural Calculation Drawings

When all approvals have been granted the structural process will start. This is an important part of the design as the drawings will present a clear scope of how to achieve the construction of the project. The project will not be able to start without the structural drawings.

10. Construction and Finishing

Once the project starts on site, the construction process it will be monitored and inspected regularly by LABC. Once completed it will also be signed off by LABC. All of our team members will focus on your project to get it completed to the highest standard.

2. Consultation

The consultation call with a member of our team who will talk with you in-depth about your project. Analysing requirements, budgets, timescales, possibilities and our process in more detail.

5. Planning Permission Drawings

Our Planning drawings service consists of;

fully investigating your Local Authorities planning guidelines, producing proposed plans, elevations, site layout, cross sections, outline specification, a location plan and producing a Design and Access statement if required. Obtaining and completing planning application forms on your behalf. Liaising with your local authority and keeping you informed of any feedback. With these sets of drawings you will be able to: Make a Planning application submission - Make a Permitted Development application to receive a Certificate of Lawfulness for your extension or loft conversion.

8. Party Wall Agreements

Generally any structural alteration within 3 meters of a Party Wall will require a party wall agreement and notices. We offer full Party Wall services.

3. Quote

During the consultation call you will receive a quote based on  your specification and requirements, and you will have various options to go ahead with our services if you are ready.

6. Building Control Drawings

Once planning permission has been granted the next stage is Building Control. These drawings are very detailed and show exactly how and with what materials the new building or extension is going to be constructed. A full set of Building Regulation drawings will include proposed plans, elevations, cross sections, details, full specification detailing construction methods, workmanship standards and quality of materials.

9. Project Management

We can project manage your whole project on your behalf including design and build stages. Take the risk and uncertainty away from your project by having a professional build the loft conversion, home extension or new build for you.

Insured, Registered and Accredited Construction Company

Efficient and Professional services

Total Architecture, Construction and M&E Services Under One Roof

Fully Detailed Quotes on Small, Mid & Large Projects

Located locally London, United Kingdom 

Small Deposit

Optional LABC Warranty 10 - 12 years

What are Lccl Construction customers saying, don't just take our word for it..


Lccl Construction worked on our loft extension and side return kitchen extension. They started work promptly and finished the project on time. They went above and beyond to cater for our needs and are very knowledgeable. If we were to do another project I would definitely use Lccl Construction again. I would not hesitate recommending this great construction company.

Elizabeth Moss

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