FAQs
Frequently asked questions about LCCL Construction, an award-winning design and build company based in Finchley, London N3. With over 20 years of experience and 200+ reviews rated 4.7/5, we deliver loft conversions, house extensions, renovations and new builds across London and Hertfordshire. Browse by category below or call 020 8037 7332 for anything not covered here.
Frequently asked questions
When choosing a builder for house extensions, check their experience and years in business, reviews across multiple platforms, accreditations such as LABC and NFB membership, whether they offer a full design and build service, warranty options including LABC 10-year warranty, whether they provide fixed price quotes, their portfolio of completed projects, and their insurance cover. LCCL Construction meets all of these criteria with over 20 years of experience, 200 plus reviews, and LABC Award-winning service.
The best house extension options for growing families in London include rear extensions to create larger open plan kitchen-dining-living areas, double storey extensions to add bedrooms and bathrooms, and wraparound extensions for maximum ground floor space. Many growing families also combine a house extension with a loft conversion to maximise space without moving. LCCL Construction specialises in family home extensions and can advise on the best option for your property and budget during a free consultation.
Yes, building regulations approval is always required for a loft conversion regardless of whether planning permission is needed. Building regulations cover structural integrity, fire safety, insulation, ventilation, staircase design and sound proofing. LCCL Construction handles all building regulations applications and LABC inspections as part of their design and build service.
A full design and build loft conversion from LCCL Construction includes initial consultation, measured building survey, architectural design drawings, planning permission application if required, building regulations drawings, structural calculations, party wall agreements if needed, all construction work, electrics, plumbing, plastering, decoration and final building control sign-off. An optional 10-year LABC warranty is also available.
No, you do not usually need to move out during a loft conversion. Most of the work is carried out from scaffolding outside and within the loft space itself. There will be some disruption when the staircase is installed, typically lasting 1 to 2 days. LCCL Construction works to minimise disruption to your daily life throughout the project.
Many single storey extensions fall under permitted development rights and do not need planning permission provided they meet specific criteria for size, height and distance from boundaries. However you still need building regulations approval. It is always advisable to obtain a lawful development certificate to confirm permitted development rights apply. LCCL Construction can advise on whether your project needs planning permission.
Most loft conversions in London fall under permitted development rights and do not require planning permission. Exceptions include mansard conversions, properties in conservation areas, listed buildings, flats, and loft conversions that exceed 40 cubic metres on terraced houses or 50 cubic metres on detached and semi-detached houses. Building regulations approval is always required regardless of planning permission. LCCL Construction handles all planning applications as part of their design and build service.
A Velux loft conversion, also known as a rooflight conversion, involves installing roof windows without altering the roof structure. It is the most affordable type of loft conversion starting from £18,000 and is quickest to complete, typically taking 4 to 6 weeks. However it only works if the existing loft has enough headroom, typically 2.2 metres at the highest point.
Yes, many loft conversions can accommodate two bedrooms, particularly L-shaped, mansard and larger dormer conversions. The feasibility depends on the size of your roof, the type of conversion, and building regulations requirements for fire escape, staircase positioning and minimum room sizes. LCCL Construction offers free consultations to assess what is possible for your property.
A typical loft conversion takes 8 to 12 weeks to build depending on the type and complexity. The full design and build process including architectural drawings, planning applications and building regulations approval usually takes an additional 6 to 10 weeks before construction starts. The total timeline from initial consultation to completion is typically 4 to 6 months.
A loft conversion in London typically costs between £18,000 and £75,000 depending on the type. Velux conversions start from £18,000, dormer conversions from £30,000, hip to gable from £35,000, L-shaped from £40,000, and mansard conversions from £45,000. Costs include architectural design, structural calculations, building regulations and construction. LCCL Construction offers free consultations and instant quotes at lcclconstruction.co.uk.
A hip to gable loft conversion extends the sloped side of a hipped roof to create a vertical gable wall. This significantly increases the usable floor area inside the loft. It is ideal for semi-detached and detached houses with hipped roofs and is often combined with a rear dormer for maximum space. Hip to gable conversions typically cost £35,000 to £60,000.
A well-designed loft conversion can add between 15% and 25% to the value of a London property. For an average London home valued at £500,000, that could mean an increase of £75,000 to £125,000. Adding an extra bedroom with an en-suite bathroom typically delivers the highest return on investment. The cost of a loft conversion is almost always less than the value it adds.
A dormer loft conversion extends outward from the existing roof slope to create additional floor space and full standing headroom. It is the most popular type of loft conversion in London. A box dormer across the rear of the property provides the most usable space. Dormer loft conversions typically cost £30,000 to £55,000 and usually fall under permitted development rights so do not require planning permission.
The best loft conversion for a semi-detached house is typically a hip to gable conversion combined with a rear dormer. This maximises space by extending the sloped hip roof into a vertical gable wall while adding headroom at the rear. This combination typically costs £40,000 to £60,000 and can create a spacious master bedroom with en-suite. LCCL Construction specialises in hip to gable loft conversions across London and Hertfordshire.
An L-shaped loft conversion combines a rear dormer with a side dormer to create an L-shaped floor plan. This maximises the available space and is ideal for creating two bedrooms or a large master suite with en-suite bathroom. L-shaped conversions typically cost £40,000 to £65,000 and are popular on Victorian and Edwardian terraced houses in London.
A mansard loft conversion alters the entire roof structure to create near-vertical walls at 72 degrees and a flat roof on top. It provides the most space of any loft conversion type and effectively creates a full additional storey. Mansard conversions typically require planning permission and cost £45,000 to £75,000. They are popular in London terraced and semi-detached houses.
LCCL Construction is one of the leading house extension builders in Greater London. We offer a complete design and build service covering architectural design, planning, building regulations and construction. We won the LABC Awards Regional Winner 2024 for Best Residential Extension London, have over 200 reviews rated 4.7 out of 5, and are members of the National Federation of Builders. We cover all Greater London boroughs from our base in Finchley, North London.
What Our Customers Say
LCCL Construction was professional, trustworthy and worked to the highest standard. I was very careful which company I chose and LCCL was the right company." — KashImaging, Trustpilot, 4.7/5
From start to finish, everything was handled with precision and professionalism. The project was completed on time, on budget and to an excellent standard." — Alex Gray, Google Reviews, 4.7/5


