Period conversions and mansion blocks across Camden and Bloomsbury, with conservation area rules that shape most refurbishment scopes. Camden falls well within the North London ground Lian Construction covers on a regular basis. For rear, side-return, wraparound and two-storey house extensions with structural engineering and Party Wall compliance in Camden, that local knowledge means fewer surprises once work is on site and a team that already understands the borough's typical property stock.
Camden's housing stock is dominated by period conversions and purpose-built mansion blocks, spread across areas such as Bloomsbury, Primrose Hill, Belsize Park and Camden Town. Many of the borough's Georgian and Victorian terraces have been split into flats over the decades, so refurbishment work here often has to account for shared freeholds, communal areas and lease conditions rather than a single owner making decisions for the whole building. Mansion blocks add another layer, typically with strict management company rules on what can be altered, when work can take place and which contractors need to be approved before starting. Original features such as sash windows, decorative cornicing, timber floors and period fireplaces are common, and conservation area status across much of the borough means these details are frequently protected rather than optional extras. Solid brick construction without a cavity is standard on the older stock, which has implications for damp management and insulation upgrades.
Where a Camden property hasn't already been converted, it tends to be a larger single-family Victorian or Edwardian house, often needing the same period-property considerations as the flats around it.
Camden's blurb points to conservation area rules shaping most refurbishment scopes in the borough, and that's the practical reality for most jobs here: a large share of Camden's residential streets sit within a conservation area, so external changes, window replacements and anything altering the street-facing appearance of a building typically need planning permission rather than falling under permitted development. For flats within mansion blocks or converted period houses, there's usually a second layer of approval needed from a freeholder or management company on top of any planning requirement, covering things like noise hours, protecting communal areas during work and using contractors who carry the right insurance. This tends to lengthen the run-up to a project compared with a straightforward house extension elsewhere in London, even where the work itself is fairly standard once it starts. Property values in Camden are high, which supports demand for higher-specification refurbishment and finishing work, but it also means mistakes or unpermitted alterations are more likely to be picked up during a future sale or lease renewal, so getting consents right from the outset matters more here than in less regulated boroughs.
Permitted Development or Full Planning Permission
Most single-storey rear extensions in London fall under the Town and Country Planning (General Permitted Development) (England) Order 2015, which allows a rear extension up to 3m deep for a terraced or semi-detached house, or 4m for a detached house, without a full planning application, subject to height and eaves limits. Go beyond that, up to 6m for a terrace/semi or 8m for a detached house, and you need prior approval under the Larger Home Extension Scheme, which runs as a lighter-touch neighbour consultation process through the council rather than a full application, with a statutory determination period of around six weeks. Side extensions have tighter limits under permitted development, generally single-storey and no wider than half the original house width, which is why most side-return jobs on terraces get combined into a full planning application alongside the rear element instead of trying to split the two. Conservation areas, and Article 4 Directions that specific boroughs apply on top of them, can remove permitted development rights for extensions entirely, meaning even a modest single-storey rear addition needs a full application with an 8-week (or longer, for larger schemes) decision timeline. We check this at the first site visit against your specific borough's local plan and any conservation area or Article 4 status before pricing, because the planning route affects the programme more than the build itself does.
Building Control: Full Plans or Building Notice
Separately from planning permission, every extension needs Building Control sign-off under the Building Regulations 2010, and there are two routes to get it: a Full Plans application, where detailed drawings and structural calculations are submitted and formally approved before work starts, typically taking 5-8 weeks; or a Building Notice, where you can start on site as little as 2 days after submission but without prior approval of the design, meaning any problems get picked up on site inspections instead of on paper beforehand. For a straightforward single-storey rear extension with a well-understood structural opening, a Building Notice can be the faster, lower-friction route. For anything with more structural or ground-condition risk - a side-return with underpinning, a two-storey addition, unusual soil conditions, or a design close to the boundary - we generally recommend Full Plans, because getting the steel sizing and foundation design checked and approved before you dig avoids a stop-work order mid-excavation if Building Control isn't satisfied. Part A covers structural stability, Part L sets the thermal performance targets for the new walls, roof, windows and doors and caps how much of the extension's floor area can be glazed, and Part H4 requires water company approval for any foundation within 3m of a public sewer. We decide the route with you at the design stage based on the specific job, not as a default answer.