We work across Forest Hill and Sydenham. The ground here rises steeply, so many properties have split levels, retaining walls and lower ground floors, which makes the structural side of an extension more involved than it looks from the street.
- Postcodes
- SE23, SE26
- Housing stock
- Victorian villas and terraces on sloping plots, with lower ground floors and retaining garden walls.
The slope is the design problem
On these plots the garden is often a metre or more above or below the ground floor. That turns a straightforward rear extension into a job with retaining structure, tanking and drainage falls to think about. It is entirely doable, but it needs to be priced honestly at the start rather than discovered at foundation stage.
Typical work here
Rear extensions with retaining walls and tanked lower ground floors, loft conversions with the dormer designed around a steep roof pitch, and structural repair to garden and boundary walls that have moved with the ground.
Recent jobs across the patch
The things people ask before they commit
How much does an extension cost in South-East London?
It depends far more on the house than on the floor area, which is why a rate per square metre is misleading. Ground conditions, drainage runs, the state of the existing structure, access for materials and the specification you choose all move the figure, sometimes substantially. We survey the property, price the work line by line and give you a fixed written quotation before anything starts, so the number you agree is the number you pay unless you change the scope.
Do I need planning permission?
Often not. Many single-storey rear extensions and rear dormers are permitted development. However, permitted development rights are restricted in conservation areas, on flats and maisonettes, and where an Article 4 direction applies, all of which are common across Blackheath, Brockley, Greenwich and Dulwich. We confirm your position at the first visit, before you spend anything on drawings.
How long will the work take?
Every project is different, so timescales can vary depending on the scope, complexity and individual requirements of the project. As a general guide, a structural opening can take one to three weeks, a garage conversion around four to six weeks, and a loft conversion around eight to twelve weeks. Larger renovations may take ten to twenty weeks. Every quotation includes a project programme outlining the expected start date and key stages, so you’ll know what to expect from the outset.
Can we stay in the house during the build?
For extensions, loft conversions and garage conversions, almost always. We build the shell before breaking through, seal the working area with dust screens and keep a working kitchen and bathroom available. For a full refurbishment we phase the work floor by floor, though most families choose to move out for the first few weeks.
Do you handle Building Control and Party Wall notices?
Yes, both are included. We submit the Building Control notice, book the inspections and hand you the completion certificate at the end. Where the Party Wall etc. Act 1996 applies we serve the notices on the adjoining owners on your behalf and build to the awarded terms.
Are you insured, and is the work guaranteed?
We carry public liability insurance and provide the certificate with the quotation. Workmanship is guaranteed on complete renewal work, as this is work we have built from start to finish; repair work is not covered by our workmanship guarantee. Manufacturer warranties on roofing membranes, glazing and boilers are registered in your name and handed over in the completion pack.
How are payments structured?
Payments are staged against agreed milestones, set out in your quotation before work begins — each instalment due only as that phase starts, so costs stay clear and predictable throughout. We don't ask for large deposits up front; the one exception is long-lead-time materials like glazing and steel, invoiced ahead of ordering, with the supplier order visible to you.
Tell us what you are trying to do with the house.
We will come out, measure up and tell you honestly whether it works. The site visit and the written quotation are free, and there is no obligation attached to either.