Loft Conversions
Across
South London
Turn your unused loft into a bedroom, bathroom, home office or living space. We manage your loft conversion from first survey to final handover — with no surprises along the way.
Proudly Serving South London
Survey to Handover
Free Loft Assessments
Your Loft is
Wasted Space
Most homes in South London are sitting on a significant amount of unused space — right above their heads. A well-executed loft conversion is one of the highest-value improvements you can make to a property, typically adding 15–20% to its value while creating a room that genuinely transforms how you live in your home.
At Kelmend Construction, we handle every aspect of your loft conversion — from the initial structural survey and planning application through to the staircase, electrics, plumbing, plastering, and decoration. One point of contact, one accountable team, no passing the buck.
Which Type
is Right for You?
Velux / Rooflight
The simplest and most cost-effective loft conversion. The roofline stays exactly as it is — Velux windows are fitted into the existing slope to bring in light and ventilation. Best suited to lofts with sufficient existing headroom (typically 2.2m or more at the ridge). No planning permission usually required and the fastest to complete.
Dormer Conversion
A box-shaped extension that projects vertically from the roof slope, creating a full-height room with vertical walls and a flat or pitched roof. Dramatically increases usable floor space and headroom compared to a Velux conversion. The most commonly built loft conversion in South London. Usually falls under permitted development for rear dormers.
Hip-to-Gable
Specific to semi-detached and detached properties with a hipped roof (where the roof slopes on all four sides). The sloping hip end is replaced with a vertical gable wall, significantly increasing the internal volume of the loft. Often combined with a rear dormer for maximum space. Planning permission is typically required.
Mansard Conversion
The most extensive loft conversion type — alters the entire roof structure to create near-vertical walls (typically 72°) and a flat roof. Maximises usable floor area and headroom across the full width of the property. Common in terraced houses across South London. Requires planning permission and full structural engineering input.
L-Shaped Dormer
Combines a rear dormer with a smaller side dormer over the back addition of the property — common in Victorian terraces throughout South London that have a rear outrigger. Creates an L-shaped loft that effectively doubles the usable floor space compared to a standard dormer. Excellent for adding a large bedroom with en-suite.
Full Roof Replacement
For properties where the existing roof structure makes a standard conversion difficult — typically older properties with complex cut roof timbers or insufficient ridge height. We replace the roof structure entirely to create a purpose-designed loft space. The most involved conversion but opens up properties that other builders might turn away.
What Makes Us
Different
Free Loft Assessment
Before anything else, we assess whether your loft is suitable for conversion — checking headroom, roof structure, floor joists, and access. Many companies skip this step and quote blind. We don't. If it's not viable, we'll tell you straight.
Structural Engineering Included
Every loft conversion requires structural calculations — new floor joists, steel beams, and the staircase opening all need engineering sign-off. We coordinate this as part of our service so you don't have to find and manage a separate engineer.
Planning & Building Regs Managed
We handle the planning application if one is needed, and manage the building control process throughout. You won't be chasing councils or inspectors — we do that so you don't have to.
Minimal Disruption to Your Home
We scaffold and weatherproof before opening up the roof, meaning your home is protected at every stage. We work methodically to keep noise, dust, and inconvenience to a minimum throughout the build.
Fully Finished to Your Spec
We don't hand over a shell and leave you to find tradespeople for the rest. We complete your loft conversion to a fully decorated, habitable standard — plastered, floored, electrics and plumbing in, ready to furnish.
South London Specialists
Victorian terraces, Edwardian semis, post-war houses — each roof type has its own quirks and constraints. We've worked across South London's housing stock and know what to look for before problems become expensive surprises.
Things Worth
Knowing
Loft conversions have a few more technical requirements than most people expect. Here's what we cover on your behalf.
Headroom Requirements
Building regulations require a minimum of 2.2m headroom at the tallest point. We assess this at the initial survey — if your loft doesn't meet this, we'll tell you honestly rather than waste your time.
Permitted Development
Rear dormers and Velux conversions often fall under permitted development — no planning application needed. We check your property against permitted development rules before assuming anything.
Planning Permission
Hip-to-gable, mansard, and front dormers typically require full planning permission. Properties in conservation areas have tighter restrictions — we know South London's conservation areas well.
Building Regulations
All loft conversions must meet building regulations — covering structural strength, fire escape, insulation, staircase gradient, and emergency egress windows. We manage building control from start to sign-off.
Fire Safety & Escape
Building regulations require a protected fire escape route from any new loft habitable room. This typically means fire doors on every room on the floor below and a mains-wired smoke alarm system.
Party Wall Notice
If your loft conversion involves work to a shared wall — common with terraced houses — you must serve a party wall notice on your neighbour before work begins. We flag and manage this early.
Our Loft Conversion
Process
Free Loft Assessment
We visit your home and assess the loft — headroom, roof structure, floor joist capacity, access, and any constraints. We give you an honest appraisal of what type of conversion is feasible and what it will involve before you spend a penny.
Design & Planning
Working with your architect (or one we recommend), we develop the drawings for your conversion. We advise on the planning route, submit any required application, and handle the party wall process if needed. We don't start building until everything is properly in place.
Structural Engineering
We commission structural calculations for the new floor joists, any steel beams, and the staircase opening. These calculations are submitted to building control as part of the regulations approval process — all managed by us.
The Build
Scaffolding goes up, the roof is opened, and the structural work begins. We manage the entire sequence — steel installation, new joists, dormer structure, roofing, windows, and weatherproofing — before moving to the interior fit-out. You get regular photo updates throughout.
First & Second Fix
Electrics, plumbing (if adding an en-suite), insulation, and plastering follow. We install the staircase, fit the fire doors, and wire the smoke alarm system to meet building regulations. Everything is inspected by building control at the required stages.
Handover & Sign-Off
Building regulations completion certificate is obtained. We do a full snagging walkthrough with you, complete any outstanding items, and hand over your new room fully finished and ready to use.
Covering
South London
We're based in South East London and carry out loft conversions across the wider South London area. Our core patch includes:
Not listed? We cover all of South London and can travel further across the city — just get in touch.
Loft Conversion FAQs
How much does a loft conversion cost in South London?
A Velux conversion typically starts from £20,000–£30,000. A dormer conversion ranges from £35,000 to £60,000 depending on size and specification. L-shaped dormers and mansard conversions sit higher — often £55,000–£80,000 or more for a fully finished result including en-suite. We'll give you an accurate figure once we've assessed your loft and discussed what you want to achieve.
Does my loft have enough headroom for a conversion?
Building regulations require a minimum of 2.2m at the highest point for a habitable loft room. Most Victorian and Edwardian terraces in South London meet this — but it's not universal. The only way to know for certain is to measure, which we do at the free assessment stage. If your loft falls short, a mansard or full roof replacement may still make it viable.
Do I need planning permission for a loft conversion?
Not always. Velux conversions and rear dormers on houses (not flats) often fall under permitted development, meaning no planning application is required. However, hip-to-gable conversions, mansards, front dormers, and any conversion on a property in a conservation area will need full planning permission. We assess this for your specific property at the start of the process.
How long does a loft conversion take?
A Velux conversion typically takes 4 to 6 weeks on site. A dormer conversion takes 8 to 12 weeks. An L-shaped dormer or mansard will take 12 to 18 weeks. This is build time — if planning permission is required, add 8 to 13 weeks before work can begin. We'll give you a realistic programme in your quote.
Can I add an en-suite bathroom to my loft conversion?
Yes — and we'd encourage it. An en-suite adds significant value and is far easier and cheaper to install during the conversion than afterwards. We install the plumbing as part of the build, running the soil pipe and water supply while the floor and walls are open. A loft bedroom with en-suite is consistently one of the highest-value additions you can make to a South London home.
Will a loft conversion add value to my home?
In most cases, yes — significantly. A well-built loft conversion in South London typically adds 15–20% to a property's value. Converting a 3-bedroom home to a 4-bedroom home by adding a loft bedroom with en-suite can add substantially more than the cost of the conversion in the right postcode. As with any building work, the quality of the finish matters — a poorly built or uncertified conversion can create problems at sale.
Ready to Use
Your Loft?
Book a free loft assessment and we'll tell you exactly what's possible — and what it will cost.
No pushy sales. No call centres. Just a straight conversation about your project.