House
extensions
in Camden Town, NW1
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Hampstead Chartered Surveyors & Building ConsultancyBehind Camden Town's terraces the rear walls, gaps and gardens are protected as well as the fronts, so an extension is sized to the row of backs it joins.
Within the Camden Town Conservation Area, Camden's 2007 strategy records many interesting historic rear elevations, regards the original pattern of backs in a street as integral to the area, and rules out rear extensions that would compromise that special character.
We start an NW1 extension from the back of the terrace: the neighbours' rear walls, earlier additions and garden lines come first, and the new room is sized to fit that pattern.
Source: Camden: Camden Town Conservation Area Appraisal and Management Strategy (adopted 4 October 2007)
Gaps at the ends of terraces
The appraisal values the gaps where terraces end: through them, over high walls, you see the gardens behind, a welcome break in a very urban place that it says contributes greatly to the character of the area.
Camden's Home Improvements guidance keeps a side extension to one storey as a rule, with a higher one possible only in some instances.
Gloucester Crescent falls under the Primrose Hill statement, which refuses side extensions that are too prominent, unbalance a group or close gaps giving views of rear gardens, mature trees or the canal.
Many of the crescent's villas already join at ground and basement level while staying apart higher up, so the trees behind stay in view.
Sources: Camden: Camden Town Conservation Area Appraisal and Management Strategy (adopted 4 October 2007), Camden Planning Guidance: Home Improvements (January 2021), Camden: Primrose Hill Conservation Area Statement, Gloucester Crescent sub-area
Albert Street and Mornington Street backs
Glimpsed from side streets, Albert Street's backs show a run of oversized, out-of-scale extensions, many put up under permitted development rights before listing and designation.
In Mornington Street, one- and two-storey buildings have filled former gardens.
An oversized extension next door is not a model for ours; we draw the row as first built and show where the new room sits within it.
Source: Camden: Camden Town Conservation Area Appraisal and Management Strategy (adopted 4 October 2007)
Gaps and gardens around Camden Square
In the Camden Square Conservation Area, Camden will resist building in the gaps between semi-detached and detached houses, and back-garden development visible from the public realm.
The appraisal explains that infilling between semi-detached villas can make the intended villa layout read as a terrace.
Gardens show most at street corners, where they run along the side road, and the appraisal warns that building there can erode those green gaps.
Losing private open space is unlikely to be accepted where it harms the area, and corner plots need particular care.
Source: Camden: Camden Square Conservation Area Appraisal and Management Strategy (adopted 11 March 2011)
Extending a house beside the canal
Behind canal-side terraces, the strategy makes the original historic pattern of extensions the measure, and rejects rear additions that would spoil the uniform back of an unspoilt group, above all where those backs are plainly visible from the water.
Its waterspace rule is that, generally, no building may encroach on the canal or the towpath, cantilever over them or bridge them.
For these houses the canal elevation is our first drawing, since it is the view both the council and the towpath share.
Source: Camden: Regent's Canal Conservation Area Appraisal and Management Strategy (adopted 11 September 2008)
Jeffrey's Street and Ivor Street
The Jeffrey's Street statement asks for rear extensions in keeping with the house and the terrace's historic pattern, one storey in most cases, and not where they would spoil an unspoilt rear elevation or take much of the garden.
Conservatories there should be small and at ground floor level; one at high level will not be permitted.
Source: Camden: Jeffrey's Street Conservation Area Statement (agreed 19 November 2002)
Height, depth and the garden that stays
Camden's guidance asks that an addition at the back be subordinate in where it sits, its form, footprint, scale, proportion and detail, and that it respect original features such as projecting bays, cornices and chimneys.
Enough garden should be left to remain a reasonable size.
Inside a conservation area the government's permitted development rules exclude rear extensions of more than one storey, anything projecting beyond a side wall, and cladding.
A single-storey room across part of the back often gives the space a family wants while leaving the upper rear windows and most of the garden.
Sources: Camden Planning Guidance: Home Improvements (January 2021), MHCLG: Permitted development rights for householders, Technical Guidance (September 2019)
Daylight, glazing and the flats above
Daylight to neighbouring windows is assessed against Camden's 45 and 25 degree tests in its amenity guidance, or by a daylight study under BRE guidance.
Camden also asks that an extension does not throw light at night onto neighbours, flats above in a divided house included, so ground-floor rooflights sit back from the main wall or use obscured glass.
Climbing Camden Road, the houses become three storeys over semi-basements and many have been split into flats, so the windows above an extension may belong to someone else.
Sources: Camden Planning Guidance: Home Improvements (January 2021), Camden: Camden Square Conservation Area Appraisal and Management Strategy (adopted 11 March 2011)
Trees, roots and footings
Many of Camden Square's street trees are in fact rooted in front gardens, and the conservation area protects every one over 75 millimetres across.
Policy D2 of Camden's Local Plan commits the council to keeping trees and garden space that add to a conservation area or set off its buildings.
On clay that shrinks and swells, footings go deeper, and nearby trees can push them deeper again.
If a tree stands near the new wall, the root survey comes before the engineer sets the foundation depth.
Sources: Camden: Camden Square Conservation Area Appraisal and Management Strategy (adopted 11 March 2011), Camden Local Plan 2017, Planning Portal: Extensions, Building Regulations: Foundations
Neighbours' footings, drains and approval
The Planning Portal expects most extensions to need building regulations approval.
Its advice for digging beside an existing footing is to go at least as deep as the neighbour's foundation, in short lengths that are concreted before the next is opened.
Approved Document H comes into play for building within 3 metres of the centreline of a sewer or drain shown on the sewer records.
Building at the boundary or excavating close to next door's foundations is work the neighbour must be told about first.
Sources: Planning Portal: Is building regulations approval needed for an extension?, Planning Portal: Extensions, Building Regulations: Foundations, GOV.UK: Approved Document H, Drainage and waste disposal (2015 edition), GOV.UK: Party walls and building work
Design that answers the street
Camden's Camden Town strategy asks applications to address the formality and regularity of its streets, and accepts that modern design can enhance the area if it responds carefully to its surroundings.
Jeffrey's Street's statement wants original natural materials, or the closest match, and will not accept concrete roof tiles, imitation slate or plastic windows.
Where an extension has a flat roof, Camden's guidance favours a biodiverse green roof with 100mm of substrate over a sedum blanket.
Sources: Camden: Camden Town Conservation Area Appraisal and Management Strategy (adopted 4 October 2007), Camden: Jeffrey's Street Conservation Area Statement (agreed 19 November 2002), Camden Planning Guidance: Home Improvements (January 2021)
What helps us price an NW1 extension
A handful of pictures helps: the rear wall seen from the end of the garden, the view down from a first-floor back window, and next door's addition if there is one.
Tell us how the new room will be used: cooking and eating, a home office or a playroom each change the orientation, the storage and the heating.
Mention any tree close to the boundary, any manhole in the garden and whether the house is in flats, so the first visit can check each one.
House extension questions for Camden Town
Will Camden allow a rear extension in the Camden Town Conservation Area?
Not one that compromises the original rhythm of rear walls in the street, which Camden counts as integral to the area.
Can I build in the gap beside my Camden Square villa?
Camden will resist building in gaps between semi-detached and detached houses there.
Can an extension overhang the canal towpath?
As a general rule nothing may be built that encroaches on, cantilevers above or bridges the water or the towpath.
Is a two-storey rear extension permitted development here?
Not in a conservation area, where only single-storey rear extensions can fall within permitted development.
Can I add a first-floor conservatory in Jeffrey's Street?
No. The statement keeps conservatories at ground level and will not permit one at high level.
How is a neighbour's daylight checked?
Against Camden's 45 and 25 degree tests, or through a daylight study following BRE guidance.
Sources: Camden: Camden Town Conservation Area Appraisal and Management Strategy (adopted 4 October 2007), Camden: Camden Square Conservation Area Appraisal and Management Strategy (adopted 11 March 2011), Camden: Regent's Canal Conservation Area Appraisal and Management Strategy (adopted 11 September 2008), MHCLG: Permitted development rights for householders, Technical Guidance (September 2019), Camden: Jeffrey's Street Conservation Area Statement (agreed 19 November 2002), Camden Planning Guidance: Home Improvements (January 2021)
Related pages
Sources
- Camden: Camden Town Conservation Area Appraisal and Management Strategy (adopted 4 October 2007)
- Camden Planning Guidance: Home Improvements (January 2021)
- Camden: Primrose Hill Conservation Area Statement, Gloucester Crescent sub-area
- Camden: Camden Square Conservation Area Appraisal and Management Strategy (adopted 11 March 2011)
- Camden: Regent's Canal Conservation Area Appraisal and Management Strategy (adopted 11 September 2008)
- Camden: Jeffrey's Street Conservation Area Statement (agreed 19 November 2002)
- MHCLG: Permitted development rights for householders, Technical Guidance (September 2019)
- Camden Local Plan 2017
- Planning Portal: Extensions, Building Regulations: Foundations
- Planning Portal: Is building regulations approval needed for an extension?
- GOV.UK: Approved Document H, Drainage and waste disposal (2015 edition)
- GOV.UK: Party walls and building work
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