Extensions and loft conversions in Hemel Hempstead
Hemel Hempstead is a new town wrapped around an older one. In Adeyfield, Bennetts End, Chaulden, Warners End, Highfield and Grovehill the 1950s to 1970s terraces, end-of-terrace houses and maisonettes dominate, often on Radburn layouts with footpaths at the front and parking courts behind. The typical project is a 3–4 m rear extension to create a kitchen-diner, a side extension on an end-of-terrace plot, a rear dormer to add a bedroom and bathroom, or a garden room. Woodhall Farm and Leverstock Green add 1970s and 1980s estate houses and inter-war semis, where two-storey side extensions over a garage are common. In Boxmoor, the Old Town and Apsley the Victorian and Edwardian terraces and villas take the classic moves of a side-return extension and a rear dormer, and Berkhamsted and Tring are period market towns with their own conservation areas.
Where the house is outside a conservation area and its permitted development rights are intact, much of this is permitted development (PD) and we secure a Lawful Development Certificate (LDC) as proof. On many new-town estates rights were removed by the original planning permission, so we check the council’s register before advising a route. Flats and maisonettes have no householder PD rights at all.
Planning constraints in Hemel Hempstead
- Conservation areas in the Old Town, Boxmoor, Berkhamsted and Tring, where roof extensions lose PD rights.
- New-town conditions and covenants removing some PD rights on the 1950s to 1970s estates; check the original planning permission.
- Green Belt around the town and between Hemel Hempstead, Berkhamsted, Tring and Kings Langley.
- Chilterns National Landscape to the west around Berkhamsted and Tring.
- Grand Union Canal, River Gade and River Bulbourne flood risk through the Old Town, Boxmoor, Apsley and Berkhamsted.
- Listed buildings along the Old Town High Street and in Berkhamsted, Tring and the villages.
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 Hemel Hempstead planning officers look for
Dacorum officers assess householder applications against the Core Strategy 2013, the Site Allocations 2017 and the council’s guidance on residential extensions. On the new-town terraces they tend to look for rear extensions that respect the pattern of the row and clear the 45-degree line to the neighbour’s nearest habitable window, with off-street parking kept; on the semis they look for side extensions set back from the front elevation and down from the ridge, with a gap kept to the boundary; and everywhere for dormers that are subordinate, set back from the eaves and clad in matching tile. Terracing effects from side extensions, full-width box dormers, loss of parking and disproportionate Green Belt extensions are the standard refusals. Dacorum 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 Hemel Hempstead
- Planning documentation
- House extensions – rear and side extensions to new-town terraces and inter-war semis
- Loft conversions – rear dormer and hip-to-gable lofts
- Permitted development and LDCs – including checks on removed PD rights
- Outbuildings and garden rooms
- Building Regulations drawings
Example projects nearby
- Side extension in Barnet – side extension and garage conversion on a 1930s semi, the same house type as Leverstock Green and Boxmoor
- Loft conversion in Hackney – rear dormer on a terrace within the 40 m³ permitted development allowance
- Garden office in Bromley – insulated garden room within the 2.5 m permitted development height
Guides
Read Permitted development rights in London and Do I need planning permission for a rear extension in London?.
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