Extensions and loft conversions in St Albans
St Albans is a district of contrasts. In the city centre the Georgian and Victorian houses of Fishpool Street, Holywell Hill and St Michael’s sit inside a very large conservation area with many listed buildings, and the typical project is a carefully detailed rear extension or a rear dormer designed to the appraisal. In Fleetville, Bernards Heath and Marshalswick the Edwardian and inter-war semis take the classic moves: a two-storey side extension over a garage, a 4–6 m rear extension, a hip-to-gable loft with a rear dormer, or a garden room. Harpenden’s larger detached houses often have room for two-storey rear extensions and substantial outbuildings, and the villages of Redbourn, Wheathampstead, Park Street and Bricket Wood mix period cottages with post-war estates.
Where the house is outside a conservation area and the Green Belt, much of this is permitted development (PD) and we secure a Lawful Development Certificate (LDC) as proof. Inside the conservation areas, and on larger Green Belt extensions, a planning application designed to local guidance is the norm. Flats in converted houses and around the station have no householder PD rights at all.
Planning constraints in St Albans
- St Albans Conservation Area, one of the largest in the country, covering the city centre, St Michael’s and Fishpool Street.
- Areas of archaeological significance across the Roman and medieval city and around Verulamium Park.
- Metropolitan Green Belt across most of the district outside the built-up areas.
- Harpenden and village conservation areas, where roof extensions lose PD rights.
- River Ver and River Colne flood risk through the city, Park Street, Redbourn and London Colney.
- Listed buildings in very high numbers across the city centre and village cores.
In the Green Belt, extensions that need planning permission must not be disproportionate to the original dwelling, which officers usually measure by floorspace and volume against the house as first built, counting any previous extensions. Outbuildings in the Green Belt face a stricter test still, since they add new built form rather than extend an existing one; a garden room that would be permitted development elsewhere may need a planning application here.
What St Albans planning officers look for
Officers assess householder applications against the saved policies of the 1994 Local Plan Review, the emerging Local Plan 2041 as it gains weight, and the council’s design guidance. On the semis they tend to look for side extensions set back from the front elevation and down from the ridge, with a gap kept to the boundary; rear extensions that clear the 45-degree line to the neighbour’s nearest habitable window; and dormers that are subordinate, set back from the eaves and clad in matching tile. In the conservation areas they expect traditional materials and no dormers on street-facing slopes. Terracing effects from side extensions, full-width box dormers and disproportionate Green Belt extensions are the standard refusals. St Albans offers paid pre-application advice. Council fees from April 2025 are £528 for a householder application and £264 for a proposed-use LDC; verify before applying.
Our services in St Albans
- Planning documentation
- House extensions – side, rear and two-storey extensions on inter-war semis and Harpenden detached houses
- Loft conversions – hip-to-gable and rear dormer lofts
- Permitted development and LDCs
- Outbuildings and garden rooms
- Building Regulations drawings
Example projects nearby
- Loft conversion in Richmond upon Thames – hip-to-gable and rear dormer on an Edwardian semi in a conservation area, the kind of house found in Fleetville and Bernards Heath
- Side extension in Barnet – side extension and garage conversion on a 1930s semi, the same house type as Marshalswick
- Rear extension in Islington – full-width rear extension on a Victorian terrace in a conservation area
Guides
Read Conservation areas: extensions and lofts and Permitted development rights in London.
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