Policy CL6 restricts small-scale alterations and additions that harm a building's character or appearance. It applies to all new basement developments, requiring high-quality design and materials. The council will resist developments that harm the existing character.
Plain-English summary of the adopted policy text below. The full text is the rule; this is the gist.
The Council will require that alterations and additio and appearance of the building and its context.
To deliver this the Council will resist small- scale d
a. harms the character or appearance of the existin
b. results in a cumulative effect which would be de area;
c. is not of high quality form, detailed design and m
Basements
22.3.46
This policy applies to all new basement d basement development is the constructio accommodation below the prevailing gro
22.3.47
Basements are a useful way to add extra buildings. While roof extensions and rea development, basements can be built wi appropriate requirements are followed. T
se of buildings, gardens and other spaces ing, parking, noise, disturbance, odours or
s
on of buildings in the borough.
mprise minor external changes to the appearance alustrades, alarms, cameras, awnings, grilles, , telecommunications equipment, satellite dishes, rking, balconies, small terraces, flagpoles, signs cing and mechanical plant, and removing physical
s may have a negligible impact, if hey may individually harm the appearance of a and cumulative effect of these small-scale atively impact on the borough’s overall high efore, a matter of strategic importance.
ings are flats5. While dwellinghouses have such as mansion blocks, often in multiple e Council receives a high number of planning perties. A consistent approach to alterations and e that the visual coherence of the building is
ns
ons do not harm the existing character
development that:
ng building, its setting or townscape;
etrimental to the character and appearance of the
materials or is not discreetly located.
development. For the purposes of this policy, on or extension of one or more storeys of ound level of a site or property.
a accommodation to homes and commercial ar extensions add visibly to the amount of built ith much less long term visual impact – provided This policy sets out these requirements.
22.3.48
Basement development in recent years h
Basements have given rise to issues abo management of traffic, plant and equipm nearby buildings. These concerns have planning applications for basements in th 2001, increasing to 182 in 2010, 294 in 2 are extensions under existing dwellings
22.3.49
In the Royal Borough, the construction o life, traffic management and the living co planning consideration. This is because populated. It has the second highest pop density per square km in England and W detached houses can have several base The excavation process can create noise involve a large number of vehicle movem
22.3.50
A basement development next door has on the quality of life, while the effect of m equivalent of having a permanent inappr concerns over the structural stability of a sustainable drainage and the impact on land and it is expedient to deal with thes harm to residents’ living conditions rathe reasons the Council considers that caref extent of basements.
22.3.51
The policy therefore restricts the extent o half the garden or open part of the site a storey in most cases. The extent of base (GEA).
22.3.52
‘Garden’ or ‘open part of the site’ is the p property. A ‘single storey’ is one that can additional floors. It is generally about 3 to allowance for proposals with a swimming
22.3.53
Restricting the size of basements will he borough by limiting the extent and durati soil to be excavated. Large basement co affect the health and well- being of resid heavy vehicles experienced for a prolong reduce this impact.
22.3.54
The townscape of the borough is urban a gardens are often a contrast, with an info regardless of their size. While basement townscape compared with other develop artificiality into the garden area and restr of each garden will enable natural landsc flexibility in future planting (including ma
92 ONS, Census 2011
93 Trees and Basements, RBKC, February 2014 and Ba
94 Impact on Basement Development on Biodiversity, RB
has been the subject of concern from residents. out noise and disturbance during construction, the ment, and concerns about the structural stability of been heightened by the growth in the number of he Royal Borough with 46 planning applications in 2012 and 450 in 2013. The vast majority of these and gardens within established residential areas.
of new basements has an impact on the quality of onditions of nearby residents and is a material the borough is very densely developed and pulation density and the highest household Wales92. Tight knit streets of terraced and semiement developments under way at any one time. e and disturbance and the removal of spoil can ments.
s an immediacy which can have a serious impact multiple excavations in many streets can be the ropriate use in a residential area. There are also adjacent property, character of rear gardens, carbon emissions. Planning deals with the use of se issues proactively and address the long term er than rely only on mitigation. For all these ful control is required over the scale, form and
of basement excavation to no more than under and limits the depth of excavation to a single ements will be measured as gross external area
private open area to the front, rear or side of the nnot be subdivided in the future to create o 4 metres floor to ceiling height but a small extra g pool may be permitted.
elp protect residential living conditions in the ion of construction and by reducing the volume of onstruction in residential neighbourhoods can dents with issues such as noise, vibration and ged period. A limit on the size of basements will
and tightly developed in character. However, rear ormal picturesque and tranquil ambience, ts can preserve the remaining openness of the pment forms, it can also introduce a degree of rict the range of planting93. Retaining at least half cape and character to be maintained, give ajor trees), support biodiversity94 and allow water
asement Visual Evidence, RBKC, February 2014 BKC, February 2014
to drain through to the ‘Upper Aquifer’959 Plan97 and the Mayor of London’s Housin role of gardens. The National Planning P policies to resist inappropriate developm gardens from the definition of previously 22.3.55
Keeping the unexcavated area of a gard in other plots allows better drainage, and biodiversity. In back gardens this area w the building.
22.3.56
On large sites, basements of more than open part of the site may be permitted in new developments located in a commerc substantial part of an urban block100. The the plant, equipment and vehicles assoc offer more opportunity to mitigate constr
22.3.57
Where a basement has already been im permission or through the exercise of pe allow further basement floors or baseme the garden or open part of the site. This forms part of the original property, or wh July 1948101. This is to ensure consisten
22.3.58
Trees make a much valued contribution biodiversity and public health benefits. W planned and executed with very close at likely to affect trees102 either on- site or n and tree protection proposal for the cons Landscape will also apply.
22.3.59
The significance103 of heritage assets104 not harmed.
22.3.60
The special architectural or historic inter includes the location and hierarchy of ro original purpose of the building, its histor
95 Royal Borough of Kensington and Chelsea Residentia
Associates, March 2013 96 Due to the impermeable London Clay which lies bene table which is fed by precipitation within the Thames Va 97 Policy 3.5 of the London Plan, GLA, July 2011 98 Para 1.2.18, 1.2.22 and 1.2.25 Housing Supplementa 99 Para 53 and Annex 2: Glossary, NPPF, March 2012 100 Urban blocks are generally bound by roads on all sid 101 The Town and Country Planning Act 1947 came into 102 Works to trees should be carried out in accordance w Development SPD 103 The value of a heritage asset to this and future gene may be archaeological, architectural, artistic or historic. physical presence, but also from its setting (as defined i 104 A building, monument, site, place area or landscape age interest (as defined in the NPPF). These include lis conservation areas, sites of archaeological interest and below)
. This policy takes into account the London ng SPG98 both of which emphasise the important Policy Framework (NPPF)99 also supports local ment of residential gardens and excludes private y developed land.
den in a single area and adjacent to similar areas d continuity of larger planting supporting will usually be the end of the garden furthest from
one storey and greater than half the garden or n certain circumstances. These will generally be cial setting or of the size of an entire or ey should be large enough to accommodate all ciated with the development within the site and ruction impacts and carbon emissions on site.
mplemented following the grant of planning ermitted development rights, the policy does not ent extensions that would exceed 50 per cent of provision would not apply to a basement which here a later addition, was constructed prior to 1st ncy and fairness of approach
to the character of the borough, and bring Works to, and in the vicinity of, trees, need to be ttention to detail. All applications for basements nearby must be accompanied by a full tree survey struction phase. Local Plan policy CR6 Trees and needs to be identified so that the significance is
rest of listed buildings goes beyond appearance. It ooms and historic floor levels, foundations, the ric integrity, scale, plan form and fabric among
al Basement Study Report, Alan Baxter and
eath the gravel terraces there is a local perched water alley. This is known as London’s Upper Aquifer
ary Guidance (SPG), GLA, November 2012
des and can contain a mix of uses o effect on 1st July 1948 with BS 5837 2012 and the Council’s Trees and
erations because of its heritage interest. That interest Significant derives not only from a heritage asset’s in the NPPF) identified as having a degree of significance meriting sted buildings, scheduled ancient monuments, non-designated heritage assets (explained in footnote
other things. Consequently, the addition lowest floor level of a listed building, or a vault, may affect the hierarchy of the his historic integrity. Basements under listed Basements in the gardens of listed build foundations. This can harm the historic i the building105. Evidence suggests that w beneficial for the adjoining buildings if th adjoining houses and executed with spe and the basement should be discreet an 22.3.61
In conservation areas, development sho appearance of the conservation area. Ba manifestations are not considered to affe areas. It is the other aspects such as the character or appearance.
22.3.62
Archaeological remains are a finite and f setting of such remains must not be thre ensure the borough’s past is not lost fore requires development to protect the sign
22.3.63
The impact of basements on non- design their merits to avoid harm to their signific
22.3.64
It is very important to minimise the visua emergency accesses, plant and other ex avoid disturbance to neighbours from lig lighting. Introducing light wells where the the streetscape can harm the character elements are allowed they need to be se existing character and appearance of the
22.3.65
Policy CE2 of the Local Plan requires su source as possible. A minimum of one m any part of a basement within a garden p of water runoff to the drainage system an planting. Care should be taken that the o permeable soil is connected to the unaff may also be required.
22.3.66
Basement construction can cause nuisa the vicinity, through construction traffic, p vibration of construction itself. The applic kept to acceptable levels under the relev
105 London Terrace Houses 1660-1860, English Heritag
106 Royal Borough of Kensington and Chelsea Resident
March 2013 (9.2.6) 107 RBKC Basements, Basements in Gardens of Listed 108 In addition to the national and statutory designations heritage assets that are important to the area. Such a d application. A non-designated heritage asset may also b contribution to the environment. Guidance is available in 109 There are a number of relevant acts and regulations Environmental Protection Act 1990 and Noise Emission
of a new floor level underneath the original any extension of an original basement, cellar or storic floor levels, and hence the original building’s d buildings are therefore resisted by the policy. dings can result in modifications to the building’s integrity and pose risks of structural damage to where a basement is built only in the garden it is his basement is structurally independent of the ecial care106107. The link between the listed building nd of an appropriate design.
ould preserve or enhance the character or asements by themselves with no external ect the character or appearance of conservation eir externally visible elements that can affect
fragile resource. The conservation, protection or eatened by development, directly or indirectly, to ever. Policy CL4(g) and (h) of the Local Plan nificance of Archaeological Priority Areas.
nated heritage assets108 must be assessed on cance.
al impact of light wells, roof lights, railings, steps, xternally visible elements. Care should be taken to ght pollution through roof lights and other forms of ey are not an established and positive feature of or appearance of an area. Where external visible ensitively designed and sited, respecting the e building, streetscape and gardens in the vicinity.
urface water run-off to be managed as close to its metre of suitably drained permeable soil above provides for both reducing the amount and speed nd the long term future of shrub and other garden original garden level is maintained and the 1m of fected part of the garden. Other SuDS measures
ance and disturbance for neighbours and others in parking suspensions and the noise, dust and cant must demonstrate that these impacts are vant acts and guidance109, taking the cumulative
ge tial Basement Study, Alan Baxter and Associates,
Buildings, Alan Baxter and Associates, February 2014 s, a local planning authority may formally identify designation will be material when assessing an be of value, and make an important positive n English Heritage’s practice guide to PPS5 including Control of Pollution Act (COPA) 1974, n in the Environment by Equipment for use Outdoors
impacts of other development proposals the building compound and the skip on s highway immediately outside the applica 22.3.67
Basement development can affect the st be set out in a forthcoming Basements S
22.3.68
Given their nature, basements are more and sewage, than conventional extensio Flooding. Fitting basements with a ‘posit technological advances) will ensure that only a ‘non return valve’ is not acceptabl sewage away from the building.
22.3.69
Applicants wishing to undertake baseme proposals with neighbours and others, w negotiations and discuss their schemes submitted. Sharing emerging proposals and businesses in the vicinity is benefici more readily taken into account.
22.3.70
A Basements SPD will be adopted which need to be submitted with basement app
Accompanying (but not part of) a statement (CMS) will need to be structural engineer, which will co conditions of the site including g will be dealt with during the cons demonstrate how the excavation temporary propping and other te safeguarding structural stability. is not controlled through the plan The Party Wall Act is more suite
Ways to minimise disturbance w will include the drilling of boreho works to minimise the effect on related cumulative impacts; the and the need for professional ve safeguarding amenity, that is no will also be included.
A draft construction traffic mana submitted with the application an Council will attach a condition re issues relating to highway safety from construction vehicles and t include vehicle stationing, mano issues in relation to residential a
Regulations 2001. The guidance includes British Standa vibration control on construction and open sites 110 Sewers often surcharge to just below manhole cover connection provides a new low point for the surcharging waste water from basements should be pumped
s into account. Every effort must be made to locate site or in exceptional circumstances in the ation site.
tructure of existing buildings. Guidance on this will SPD (see paragraph 22.3.71).
e susceptible to flooding, both from surface water ons, and applicants are advised to see policy CE2: tive pumped device’110 (or equivalent reflecting t they are protected from sewer flooding. Fitting le as this is not effective in directing the flow of
ents are strongly advised to discuss their who will be affected, commence party wall with the Council before the planning application is related to traffic and construction with residents ial as local knowledge and their needs can be
h will provide guidance for the information that will plications, including the following:
a planning application, a construction method e submitted by an appropriately qualified civil or ontain a report into the ground and hydrological groundwater flow and explain how these matters struction of the site. The CMS will also n, demolition and construction work (including emporary works) can be carried out while . The structural stability of the development itself nning system but through Building Regulations. ed to dealing with damage related issues.
will also be included in the CMS. Detailed matters oles; impact on trees; the sequence of temporary neighbours; water flow; the consideration of link between a basement and the host property erification of certain works. Guidance relating to oise, vibration and dust from construction works
agement plan (CTMP) will be required to be nd where planning permission is granted the equiring a full CTMP. The CTMP will address y, the free flow of traffic, noise associated with/ the availability of parking. Detailed matters will oeuvring and routeing, parking suspensions and and workplace disturbance, arising from vehicle
ard 5228-1 2:2009: Code of practice for noise and
r level and so connecting a basement via gravity g sewer to discharge to. To reduce the risk of flooding,
stationing, loading and unloadin account and allow for other activ (including those of utility compan 22.3.71
The Council will monitor the policy to ass within five years of its adoption.