London & Hertfordshire home extension planning rules by council

By Anderson & the LCCL Construction Team | Finchley N3

Last verified: 8 September 2026 · Next scheduled review: 1 April 2027. Fees and Article 4 directions change most often — check the council's own page before relying on a figure.

What this page is

One page, 27 councils, the same questions answered for each: which local plan applies, which householder design guide the case officer will open, how deep a rear extension can go, what the two-storey and side rules are, how dormers are judged, what the basement rules are, whether the council uses a fixed 45° daylight test, which conservation areas have lost permitted development under Article 4, and who runs building control. Every entry is drawn from the council's own adopted plan, SPD or Article 4 schedule — nothing is taken from other builders' or architects' websites. Where a council has no published numeric standard we say so rather than inventing one.

Cite this page: LCCL Construction, London & Hertfordshire home extension planning rules by council, verified 8 September 2026, https://www.lcclconstruction.co.uk/planning-rules-by-council

The national rules every council sits on top of

• Householder planning application fee: £548 from 1 April 2026 (plus Planning Portal service charge)
• Lawful Development Certificate (proposed): half the householder fee
• Larger home extension (prior approval): prior approval, 42 days, £249; 6 m attached / 8 m detached single-storey rear
• Statutory decision period: 8 weeks from validation (statutory)
• Permitted-development loft volume: 40 m³ terrace, 50 m³ semi or detached (outside conservation areas / Article 4)
• Party Wall Act notice periods: 2 months' notice for works to a shared wall, 1 month for excavation within 3 m / 6 m

Sources: Town and Country Planning (Fees) (Amendment) Regulations SI 2025/342; Planning Portal fee sheet 2026; Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2 Part 1 Classes A and B; Party Wall etc. Act 1996.

Permitted development (Class A/B) is the baseline outside conservation areas. Inside a conservation area, roof extensions, side extensions and two-storey rear extensions need planning permission, while a single-storey rear extension within the national 3 m / 4 m limit is still permitted development unless an Article 4 direction removes it. Listed buildings need listed building consent for almost any alteration.

How to read the entries

Figures are the council's published design standards — what the case officer measures a proposal against — not permitted-development limits. A scheme outside them can still be approved on its merits and a scheme inside them can still be refused on amenity or heritage grounds. Paragraph references in brackets point to the council document named under Householder guidance. Where a line is missing, we found no published standard.

Councils covered

North London: Barnet, Enfield, Haringey · North / North West London: Camden · North / Central London: Islington · North / East London: Hackney · Central / North West London: Westminster · Central London: Kensington & Chelsea · North West London: Brent · South West / West London: Hammersmith & Fulham · South West London: Wandsworth, Lambeth, Merton, Richmond upon Thames · West London: Ealing, Hounslow · East London: Tower Hamlets, Waltham Forest, Newham · South East London: Southwark, Lewisham, Greenwich, Bromley · Hertfordshire: St Albans, Watford, Hertsmere, Welwyn Hatfield, Broxbourne

North London

Barnet

• Local plan: Local Plan 2021–2036 (adopted 4 Mar 2025)
• Householder guidance: Sustainable Design and Development Guidance SPD, Part 4 (adopted 15 Jun 2026)
• Single-storey rear: 3 m terrace / 3.5 m semi / 4 m detached; ≤ half garden; 4 m pitched, 3 m eaves (SPD 4.37–4.42)
• Two-storey rear: ≤ half width, 3 m deep; 2 m from attached neighbour, 1 m detached (4.53–4.57)
• Side extensions: ≤ half original width; first floor 1 m to boundary, 0.5 m set-back, ridge 0.5 m below (4.69–4.74)
• Lofts and dormers: 0.5 m in from eaves, ridge and edges (4.87); front dormers not supported (4.85); hip-to-gable acceptable on balanced pairs (4.84)
• Basements: single storey, 2.5 m head height, within rear-extension depth, ≤ half garden, front lightwell ≤ 1 m (4.103–4.121)
• Daylight / 45° test: No numerical test; officers weigh loss of light to habitable-room windows (4.7–4.8)
• Article 4 directions: 10 of 16 conservation areas incl. Hampstead Garden Suburb (1971), Monken Hadley, Totteridge, Mill Hill; borough-wide small-HMO since 29 May 2016
• Pre-application advice: £548 application; pre-app per council schedule
• Building control: LABC Barnet (in-house)
• Other limits: ≤ 25% volume increase (4.163)

See our Barnet area guide for housing types, prices and a local LCCL project.

Enfield

• Local plan: Core Strategy 2010 + Development Management Document (Nov 2014); new Local Plan at examination
• Householder guidance: DMD policies 10–14
• Single-storey rear: 3 m terrace and semi / 4 m detached; flat roof 3 m, pitched 4 m ridge / 3 m eaves (DMD 11)
• Two-storey rear: first floor limited by 30° line from nearest neighbouring first-floor window (DMD 11)
• Side extensions: ≥ 1 m from boundary, no terracing effect (DMD 14)
• Lofts and dormers: inset 500–750 mm from eaves, ridge and edges; front dormers only where not dominant (DMD 13)
• Basements: No DMD policy; Basement Impact Assessment required by validation checklist (Nov 2023)
• Daylight / 45° test: Codified: 45° from mid-point of nearest ground-floor window; 30° at first floor (DMD 11(2)(b))
• Article 4 directions: 2006 direction on 11 conservation areas incl. Enfield Town, Winchmore Hill, Southgate Green, Bush Hill Park; Grange Park/Meadway 2008; Enfield Town 2017
• Pre-application advice: £250 householder / £443 in CA or listed (Apr 2024 schedule)
• Building control: Enfield Building Control (in-house, LABC)

See our Enfield area guide for housing types, prices and a local LCCL project.

Haringey

• Local plan: Development Management DPD (24 Jul 2017)
• Householder guidance: No borough-wide extensions SPD; council 'common projects' guidance
• Single-storey rear: In conservation areas permission needed over 3 m; larger-home route accepted outside
• Two-storey rear: Permission needed in conservation areas; extensions to complement host (DM9/DM12)
• Side extensions: Permission needed in conservation areas
• Lofts and dormers: Rear preferred; set in ≥ 1 m from gable edges, 0.5 m from hips
• Basements: DM18 — structural stability to be demonstrated
• Daylight / 45° test: No 45° rule; DM1 + BRE guide
• Article 4 directions: Rookfield Estate (1978), Noel Park, Peabody Cottages, Tower Gardens only; none in Muswell Hill, Crouch End or Highgate
• Pre-application advice: £312 written express / £498 with meeting / £103 general
• Building control: Haringey Building Control (in-house, LABC)

North / North West London

Camden

• Local plan: Camden Local Plan 2017
• Householder guidance: CPG Home Improvements (15 Jan 2021); CPG Basements (Jan 2021)
• Single-storey rear: Qualitative — subordinate, reasonably sized garden retained (CPG 2.1.1)
• Two-storey rear: Qualitative
• Side extensions: Single storey (CPG 2.1.2)
• Lofts and dormers: Subordinate to the roof slope (CPG 2.2)
• Basements: Borough-wide Article 4 (in force 1 Jun 2017): all basements need permission; one storey, ≤ 50% of each garden, < 1.5× footprint, ≤ 50% of house depth beyond rear wall; audited Basement Impact Assessment (Policy A5)
• Daylight / 45° test: Codified: 45° and 25° tests or BRE assessment (CPG 2.1.1)
• Article 4 directions: Hampstead, Belsize, Fitzjohns/Netherhall, Swiss Cottage — 1 Sep 2010 (amended Jun 2026); Primrose Hill 3 Mar 1983; basements borough-wide
• Pre-application advice: £481.50 level 1 / £963 level 2 inc. VAT; £46 email admin fee
• Building control: Camden Building Control (in-house)

See our Camden area guide for housing types, prices and a local LCCL project.

North / Central London

Islington

• Local plan: Islington Local Plan (28 Sep 2023) — DH4 basements
• Householder guidance: Conservation Area Design Guidelines (2002); Basement Development SPD (Jan 2016)
• Single-storey rear: CA guidelines: full-width rear above one storey not normally permitted
• Two-storey rear: Half-width above two storeys not normally permitted
• Side extensions: Canonbury: ≤ 3 m high, set back ≥ 3 m
• Lofts and dormers: No front/side dormers in Barnsbury or Canonbury; mansards only on scheduled buildings (Barnsbury); presumption against roof extensions in Whitehall Park
• Basements: Single storey below lowest original habitable floor; ≤ 3 m floor-to-ceiling; < 50% of original garden; ≥ 1 m soil + 200 mm drainage beyond 3 m of rear wall; Structural Method Statement
• Daylight / 45° test: No 45° rule found; BRE
• Article 4 directions: 40 of 42 conservation areas (windows, doors, painting)
• Pre-application advice: £480 written / £700.80 with site visit / £1,440 listed (from 2 Jan 2025); 30 working days
• Building control: Islington Building Control (in-house, LABC)

See our Islington area guide for housing types, prices and a local LCCL project.

North / East London

Hackney

• Local plan: LP33 (22 Jul 2020)
• Householder guidance: Residential Extensions and Alterations SPD (approved Dec 2025, in effect Jan 2026)
• Single-storey rear: 3 m terrace / 3.5 m semi / 4 m detached; retain ≥ 50% of rear garden; below first-floor sills (s.3.5)
• Two-storey rear: ≤ half width and half ground-floor depth; one storey below eaves
• Side extensions: ≤ half width; ≥ 1 m from boundary; ≥ 500 mm behind front line
• Lofts and dormers: ≥ 0.5 m below ridge and from hips, ≥ 1 m above eaves, ≤ half roof height; mansards ≤ 70° outside CAs; roof extensions on unaltered CA rooflines not generally acceptable (6.12); hip-to-gable not acceptable in CAs
• Basements: Single storey; footprint < 1.5× host; ≤ 50% of house depth into garden and ≤ 50% of garden depth; lightwells ≤ 50% of front garden; 2.15 m headroom (s.7)
• Daylight / 45° test: Codified: 45° from centre of nearest ground-floor habitable window, plan and elevation (s.3)
• Article 4 directions: Shacklewell Green (22 Oct 2019), Brownswood & Well Street (9 May 2025), Beck Road (28 May 2025); none on Stoke Newington, Clissold Park, Clapton
• Pre-application advice: £310 written / £155 follow-up / £430 listed (from 1 Apr 2026)
• Building control: Hackney Building Control (in-house, LABC)

See our Hackney area guide for housing types, prices and a local LCCL project.

Central / North West London

Westminster

• Local plan: City Plan 2019–2040 (21 Apr 2021; partial review 21 Jan 2026)
• Householder guidance: Conservation area audits (SPDs); Development and Demolition in Conservation Areas SPG
• Single-storey rear: Extensions to stop at the penultimate storey or lower; significant garden retained (DES 7I)
• Two-storey rear: As above
• Side extensions: Case by case
• Lofts and dormers: Traditional mansards most appropriate on 18th/19th-century terraces (DES 7J); St John's Wood audit: roof extensions unlikely to be acceptable (4.78)
• Basements: City-wide Article 4 (31 Jul 2016): all basements need permission; one storey below lowest original floor; ≤ 50% of curtilage (exception under 8 m sites); ≥ 1 m soil + 200 mm drainage; engineer-certified structural methodology; Code of Construction Practice
• Daylight / 45° test: No 45° rule found
• Article 4 directions: Basements city-wide; Abbey Gardens NW8 (1969), Queen's Park Estate W10 (1992), Bristol Gardens, Moncorvo Close, Relton Mews, Sussex Gardens
• Pre-application advice: £456 written householder (28 days) / £912 householder basement with meeting (2025/26)
• Building control: Westminster Building Control (in-house)

See our Westminster area guide for housing types, prices and a local LCCL project.

Central London

Kensington & Chelsea

• Local plan: Local Plan 2024 (24 Jul 2024) — CD11 basements, CD12 roofs, CD13 extensions
• Householder guidance: Basements SPD (14 Apr 2016); 38 conservation area appraisals
• Single-storey rear: Per conservation area appraisal (e.g. Ladbroke: additions to formal rear elevations onto communal gardens have harmed the group, 3.64)
• Two-storey rear: Per appraisal
• Side extensions: Per appraisal
• Lofts and dormers: Ladbroke: enlarged or added dormers on uniform terraces 'deleterious' (3.57)
• Basements: Borough-wide Article 4 (28 Apr 2016): all basements need permission; ≤ 50% of each garden; one storey; ≥ 1 m soil above any part beneath a garden; no excavation under a listed building; Construction Traffic Management Plan (CD11)
• Daylight / 45° test: No 45° rule found
• Article 4 directions: 200+ street-specific directions in conservation areas (1969–2014); Norland 3 Jul 2013 (any enlargement/alteration); basements borough-wide
• Pre-application advice: £559 level 1/2, £680 level 3; with subterranean works £722 / £1,089 / £1,210 (from 1 Apr 2026)
• Building control: RBKC Building Control (in-house, LABC Partner Authority)

See our Kensington & Chelsea area guide for housing types, prices and a local LCCL project.

North West London

Brent

• Local plan: Local Plan 2019–2041 (Feb 2022)
• Householder guidance: Residential Extensions and Alterations SPD (16 Jan 2025)
• Single-storey rear: Full width up to 6 m attached / 8 m detached outside CAs (3.1.2–3.1.3); first 3–4 m up to 4 m high, eaves ≤ 3 m; ≤ half garden (3.1.4); in Queen's Park CA permission beyond 3 m / 4 m
• Two-storey rear: ≤ 3 m attached / 4 m detached (3.2.3–3.2.4)
• Side extensions: Single storey to boundary (3.3.10); two-storey set back ≥ 0.5 m at first floor (3.4.2)
• Lofts and dormers: Rear dormer full width of original roof, ≥ 0.2 m up from eaves, below ridge (3.6.2, 3.6.5); roof alterations need permission in Queen's Park CA
• Basements: Basements SPD (numbers not restated here)
• Daylight / 45° test: Codified for two-storey rear: must not cross 45° from middle of nearest habitable-room window (3.2.5)
• Article 4 directions: Queen's Park CA (front windows/doors, painting, paving, walls, roof tiles, chimneys, outbuildings)
• Pre-application advice: £195.60 written householder; meeting +£195.60; 20 working days
• Building control: Brent Building Control (in-house)

See our Brent area guide for housing types, prices and a local LCCL project.

South West / West London

Hammersmith & Fulham

• Local plan: Local Plan (28 Feb 2018); new plan at Regulation 18
• Householder guidance: Planning Guidance SPD (28 Feb 2018) — key principles HS4, HS6, HS7
• Single-storey rear: Not normally more than 3.5 m long; retain 4 m to rear boundary; ≤ 50% of original rear open area (HS4)
• Two-storey rear: Per HS principles
• Side extensions: Per HS principles
• Lofts and dormers: Per HS principles
• Basements: Borough-wide Article 4 (26 Apr 2018): all basements need full permission; one storey; ≤ 50% of house/garden depth; ≥ 1 m soil; Construction Method Statement by qualified engineer (restated in emerging draft policy DH10)
• Daylight / 45° test: Codified: 45° from rear boundary (HS6) and unobstructed 45° from neighbouring windows; new windows ≥ 18 m apart (HS7)
• Article 4 directions: Basements borough-wide; property-specific directions in conservation areas
• Pre-application advice: £435 written (10 working days) / £630 meeting / £1,320 basement or listed (2025/26)
• Building control: H&F Building Control (in-house)

See our Hammersmith & Fulham area guide for housing types, prices and a local LCCL project.

South West London

Wandsworth

• Local plan: Local Plan (19 Jul 2023) — LP5 extensions, LP6 basements
• Householder guidance: Housing SPD (Nov 2016); basement guidance (Jun 2015)
• Single-storey rear: Qualitative — subordinate (Housing SPD s.4)
• Two-storey rear: Sited away from neighbour's boundary (4.21–4.23)
• Side extensions: Qualitative
• Lofts and dormers: Qualitative
• Basements: Keep ≥ 50% of front garden; front lightwell leaving ≥ 2 m; retain ≥ half rear garden depth; ≥ 1 m soil; no multi-level basements; Construction Method Statement for listed/heritage
• Daylight / 45° test: BRE Site Layout Planning guide (4.22); no fixed 45° rule
• Article 4 directions: Street-specific: 15–36 Commondale (Oct 2000), 23–67 Westover Road (Jul 2000), 62–72 Wandsworth Common West Side (2001), Heaver Estate
• Pre-application advice: £146 written / £293 meeting / £439 both (2026/27); free duty planner email (20 working days)
• Building control: Shared Richmond & Wandsworth service

See our Wandsworth area guide for housing types, prices and a local LCCL project.

Lambeth

• Local plan: Local Plan 2021 — Q11 extensions, Q27 basements
• Householder guidance: Lambeth Design Guide SPD (8 Aug 2023), Parts 4 and 5
• Single-storey rear: Subordinate (4.45); infills single storey (4.55); no metre limit
• Two-storey rear: Closet-return upper floors end half a storey below eaves (4.49)
• Side extensions: ≥ 1 m to boundary above ground (4.68)
• Lofts and dormers: Rear only, cill ~1 m, head ≥ 2.1 m (4.90–4.91); rear mansard 70° to 2.3 m, not on hipped roofs, generally not in CAs (4.101–4.102); half-hip preferred over hip-to-gable on clay-tiled roofs (4.105)
• Basements: One floor below ground (5.28); ≥ 70% of rear garden free at original level (5.30); ≤ 3 m floor-to-ceiling (5.33); BIA screening for all basements
• Daylight / 45° test: BRE 209 (2022); no fixed 45° rule
• Article 4 directions: None on Clapham, Abbeville Road or Brixton CAs; Lansdowne Gardens, Albert Square, Stockwell Park (1975), Hyde Farm (2002), Streatham Lodge (2010) etc.; small-HMO 2024
• Pre-application advice: £491 written / £820.46 with meeting / £984.88 in CA or listed (2026/27); target 35 days
• Building control: Lambeth Building Control (in-house, LABC partner)

See our Lambeth area guide for housing types, prices and a local LCCL project.

Merton

• Local plan: Local Plan (20 Nov 2024) — D12.4 extensions, D12.11 basements
• Householder guidance: Basement and Subterranean Design SPD (Mar 2017)
• Single-storey rear: Qualitative — respect form, scale, bulk and proportions (D12.4)
• Two-storey rear: Qualitative; no long conjoined facades
• Side extensions: Qualitative
• Lofts and dormers: Appropriate size, type, form and material (D12.4)
• Basements: Single storey; beyond original walls to ≤ 50% of original footprint; ≥ 1 m soil beyond footprint; not under listed buildings; lightwells need permission; Basement Impact Assessment
• Daylight / 45° test: No fixed 45° rule
• Article 4 directions: Householder: John Innes Merton Park and Wilton Crescent only; small-HMO 7 wards from 17 Nov 2022 + 13 wards from 24 Mar 2026
• Pre-application advice: £250 incl. 15-minute virtual meeting; +£200 per further meeting
• Building control: Merton Building Control (in-house)

See our Merton area guide for housing types, prices and a local LCCL project.

Richmond upon Thames

• Local plan: Local Plan 2024–2039 (7 Oct 2025)
• Householder guidance: House Extensions and External Alterations SPD (Jun 2015)
• Single-storey rear: 3 m terrace / 3.5 m semi / 4 m detached; Victorian infill eaves ≤ 2.2 m
• Two-storey rear: ≤ half width of original house
• Side extensions: Set back ≥ 1 m behind front, 1 m from side boundary
• Lofts and dormers: Below ridge, leaving a significant area of roof
• Basements: None in functional flood plain (zone 3b); under more than half the front garden discouraged
• Daylight / 45° test: BRE 25° and 45° tests referenced in SPD
• Article 4 directions: Street-level directions in Richmond CAs (Bellevue Rd, Glebe Rd, Hillersdon Rd, The Vineyard etc.), Kew, Sheen Road, Richmond Riverside
• Pre-application advice: £190 written householder (from 26 Jun 2026); £660 listed with site visit; 20 working days
• Building control: Shared Richmond & Wandsworth service
• Other limits: Garden retention 40 m² (2-bed) / 70 m² (3+ bed)

See our Richmond upon Thames area guide for housing types, prices and a local LCCL project.

West London

Ealing

• Local plan: Development Management DPD (10 Dec 2013); new Local Plan at examination
• Householder guidance: SPD 4 Residential Extensions (2004)
• Single-storey rear: ≤ 3 m deep and 3 m high (SPD 4 s.5)
• Two-storey rear: Case by case
• Side extensions: ≤ 3 m high single storey; first floor set back ≥ 1 m from front and ≥ 1 m from side boundary; ridge ≥ 0.5 m below main (s.4)
• Lofts and dormers: ≥ 0.5 m from ridge, edges and eaves; front dormers rarely acceptable; hip-to-gable on semis/terraces normally refused (s.6)
• Basements: No numeric standard (s.10)
• Daylight / 45° test: No 45° rule; policy 7B amenity
• Article 4 directions: Brentham Garden Estate (1976), Bedford Park, Hanger Hill Garden Estate, Hanger Hill (Haymills), Churchfields, The Grove
• Pre-application advice: No householder category — planning appointment £311.40 verbal / £386.14 written
• Building control: Ealing Building Control (in-house)
• Other limits: Garden ≥ 50 m² (< 5 habitable rooms) / 75 m²

See our Ealing area guide for housing types, prices and a local LCCL project.

Hounslow

• Local plan: Local Plan 2015–2030 (15 Sep 2015); review at examination, adoption programmed 2026
• Householder guidance: Residential Extension Guidelines SPD (Dec 2017)
• Single-storey rear: 3.05 m terrace / 3.65 m semi / 4.25 m detached, below first-floor windows (4.3)
• Two-storey rear: ≤ half width, ≤ 2.5 m deep, ≥ 2 m from neighbour's side wall (4.6)
• Side extensions: Single storey set back 1 m, below first-floor eaves (4.4); two storey set back 1 m, < half width, ridge ≥ 0.5 m lower (4.5)
• Lofts and dormers: ≥ 0.3 m below ridge, ≥ 0.5 m above eaves, ≥ 0.5 m from sides (1 m larger houses) (4.10); in CAs < half roof width, 1 m from ridge and eaves; front dormers and hip-to-gable not normally acceptable (6.2)
• Basements: Single subterranean floor; garden extent as rear-extension depths; ≥ 1 m soil; lightwells ≤ 1 m front / ≤ 2 m rear (4.7); none in flood zone 3b (3.9)
• Daylight / 45° test: BRE; 45° not codified
• Article 4 directions: Bedford Park (24 Jul 2001), Gunnersbury Park; small-HMO borough-wide from 4 Sep 2023
• Pre-application advice: £408.44 written / £558.55 meeting / £769.87 site visit / £1,232.82 listed (2026/27)
• Building control: Hounslow Building Control (in-house)
• Other limits: Garden retained ≥ footprint of original house (3.6)

See our Hounslow area guide for housing types, prices and a local LCCL project.

East London

Tower Hamlets

• Local plan: Local Plan 2031 (15 Jan 2020); new plan submitted 16 Feb 2026
• Householder guidance: No extensions SPD; 58 conservation area appraisals and management guidelines
• Single-storey rear: Subordinate; acceptable where not visible from the public realm (Victoria Park / Driffield guidelines)
• Two-storey rear: Per appraisal
• Side extensions: Side-return infills and wrap-arounds acceptable on suitable gardens
• Lofts and dormers: Terrace rooflines protected; main-roof additions only on scheduled properties; mansards to design sheets
• Basements: No basement policy found
• Daylight / 45° test: D.DH8 amenity; no codified 45°
• Article 4 directions: No householder directions; small-HMO in a defined implementation area (from 1 Jan 2021)
• Pre-application advice: £119 written letter (£130 listed/CA); £240 site visit; £360 meeting (from Apr 2026)
• Building control: Tower Hamlets Building Control (in-house, LABC)

See our Tower Hamlets area guide for housing types, prices and a local LCCL project.

Waltham Forest

• Local plan: Local Plan Part 1 2020–2035 (29 Feb 2024)
• Householder guidance: Residential Alterations and Retrofit SPD (Jun 2026)
• Single-storey rear: No fixed depth; over 3 m long ≤ 2.4 m high at boundary; below first-floor sill; good-size garden retained (7.5.4)
• Two-storey rear: ≤ 2 m from original rear wall terrace and semi, ≤ 3 m detached; eaves at or below host (7.6.2)
• Side extensions: Set back ≥ 0.5 m from front line (7.7.3); ≤ 2.4 m at boundary single storey; two-storey ridge ≥ 0.5 m below main; 1 m gap where side gaps define the street
• Lofts and dormers: Set in ≥ 0.25 m from ridge and eaves, ≥ 0.5 m from roof sides (7.9.11); rooflights ≤ 0.15 m proud; front dormers typically not supported; hip-to-gable not usually approved
• Basements: Retain ≥ 50% of front garden (7.10.7); lightwell ≥ 1.5 m deep where a habitable room relies on it
• Daylight / 45° test: Codified: 25° in section from centre of lowest ground-floor window; 45° in plan and elevation (7.4.3–7.4.5)
• Article 4 directions: 10 of 15 conservation areas incl. Walthamstow Village (1977); Highams Area of Special Character (2 Sep 2020); small-HMO borough-wide
• Pre-application advice: £335 inc. VAT (written up to 8 weeks or 20-minute appointment)
• Building control: Waltham Forest Building Control (in-house, LABC)
• Other limits: Outbuildings ≤ 2.5 m, ≤ 50% coverage (7.12.2)

See our Waltham Forest area guide for housing types, prices and a local LCCL project.

Newham

• Local plan: Local Plan 2018 (Dec 2018); new plan at examination since Jul 2025
• Householder guidance: Altering and Extending Your Home SPD (Feb 2018) — qualitative
• Single-storey rear: Subservient with clear set-backs (SPD s.2); Woodgrange Estate: ground-floor rear only, ≤ 3 m from main house / ≤ 2.5 m from closet wing, pitched roof below sills
• Two-storey rear: Qualitative
• Side extensions: Qualitative
• Lofts and dormers: Woodgrange: normally not permitted; rear-slope conservation rooflights only (max three)
• Basements: No policy found
• Daylight / 45° test: No codified 45°
• Article 4 directions: Woodgrange (1977), Durham Road, Romford Road; small-HMO borough-wide from 31 Jul 2013
• Pre-application advice: £180 written / £144 Teams meeting (Feb 2026 schedule)
• Building control: Newham Building Control (in-house)

See our Newham area guide for housing types, prices and a local LCCL project.

South East London

Southwark

• Local plan: Southwark Plan 2019–2036 (23 Feb 2022) — P56 amenity
• Householder guidance: Householder Development SPD (7 Jul 2025) — qualitative
• Single-storey rear: Subservient and not visually dominant (3.2.2); case by case
• Two-storey rear: Case by case
• Side extensions: Case by case (3.4)
• Lofts and dormers: Case by case (3.6); traditional brick/slate in CAs
• Basements: Case by case (3.8)
• Daylight / 45° test: P56 + BRE; no codified 45°
• Article 4 directions: Sunray Estate; a few individual sites; small-HMO and Class E directions
• Pre-application advice: £317.16 written or meeting / £634.32 both (2026/27)
• Building control: Southwark Building Control (in-house, LABC)
• Other limits: Fences ≤ 1 m front / 2 m rear; decking ≤ 300 mm and ≤ 50% of rear garden (2.10)

See our Southwark area guide for housing types, prices and a local LCCL project.

Lewisham

• Local plan: Local Plan 2020–2040 (16 Jul 2025)
• Householder guidance: Alterations and Extensions SPD (24 Apr 2019)
• Single-storey rear: Generally ≤ 3 m deep (4.2.3); ≤ 50% of garden depth; ≤ 3 m high at boundary if ≤ 3 m long, ≤ 2.5 m if longer
• Two-storey rear: Only with exceptional design quality (4.3.2); generally unacceptable in CAs
• Side extensions: Single storey ≤ half frontage, set back ≥ 150 mm (4.4.4); two storey ≥ 1 m from boundary, ≥ 1 m back from front
• Lofts and dormers: Front dormers resisted; rear dormers if well proportioned; hip-to-gable needs exceptional design in CAs; rooflights ≤ 150 mm proud (5.5.3)
• Basements: One storey below original ground floor (4.8.8); no wider than house; ≤ 3 m beyond rear wall or quarter of garden (4.8.9); front lightwells ≤ 1.5 m, ≤ one-third frontage (4.8.11); ≥ 2.4 m headroom (4.8.15)
• Daylight / 45° test: Codified: 45° upward and sideways from centre of affected window; 25° guide
• Article 4 directions: 26 conservation areas incl. Blackheath, Brockley, Telegraph Hill, Forest Hill; small-HMO borough-wide (Mar 2020 / Jan 2024)
• Pre-application advice: Four-tier advice service (fees per council schedule)
• Building control: Lewisham Building Control (in-house)

See our Lewisham area guide for housing types, prices and a local LCCL project.

Greenwich

• Local plan: Core Strategy with Detailed Policies (30 Jul 2014)
• Householder guidance: Residential Extensions, Basements and Conversions guidance (2018)
• Single-storey rear: 3–3.6 m terrace/semi, 4 m detached standard; ≤ 50% of garden
• Two-storey rear: Case by case
• Side extensions: ≥ 0.3 m off boundary; 1 m from road boundary on corners; < half width of house
• Lofts and dormers: Front dormers generally refused; hip-to-gable not permitted; rooflights not to roof edges
• Basements: One level below ground, generally within house footprint; two-storey resisted; lightwells as small as possible; no habitable rooms in Flood Zone 3
• Daylight / 45° test: DH(b) amenity + BRE
• Article 4 directions: Ashburnham Triangle (2014); others per conservation area
• Pre-application advice: Per council schedule
• Building control: Royal Greenwich Building Control (in-house)

See our Greenwich area guide for housing types, prices and a local LCCL project.

Bromley

• Local plan: Bromley Local Plan (16 Jan 2019) — Policies 6, 8, 37, 42, 44
• Householder guidance: No extensions SPD; Urban Design Guide SPD (5 Jul 2023)
• Single-storey rear: Scale, form and materials to respect host (Policy 6)
• Two-storey rear: Two-storey flat-roofed side extensions to traditional houses normally resisted unless well set back (Policy 6)
• Side extensions: ≥ 1 m from side boundary at two storeys or higher (Policy 8)
• Lofts and dormers: Appropriate to the roofscape (Policy 6); roof rights removed in Petts Wood ASRC and Chislehurst Road (19 Jul 2022)
• Basements: No policy found
• Daylight / 45° test: Policy 37 + BRE
• Article 4 directions: Petts Wood ASRC / Chislehurst Road roof rights (2022); upward-extension rights removed in 16 areas (2022); small-HMO borough-wide Sep 2022; older CA directions (Bickley, Foxgrove, Chelsfield Park etc.)
• Pre-application advice: £250 written householder (£720 listed) — 2024 schedule
• Building control: Bromley Building Control (in-house, LABC)

See our Bromley area guide for housing types, prices and a local LCCL project.

Hertfordshire

St Albans

• Local plan: District Local Plan Review 1994; new Local Plan at main modifications (Apr 2026, significant weight)
• Householder guidance: Residential extensions and replacement dwellings in the Green Belt SPG (26 May 2004); Design Advice Leaflet 2
• Single-storey rear: National PD volumes outside CAs; district figures not published in machine-readable form
• Two-storey rear: Case by case
• Side extensions: Case by case
• Lofts and dormers: Case by case
• Basements: No policy found
• Daylight / 45° test: Not codified
• Article 4 directions: Verulam & Fishpool Street, Sopwell Lane & Albert Street, Cunningham Avenue, Childwickbury ('most PD removed'); 15 rural directions
• Pre-application advice: £208.80 householder / £306 listed or CA — written only, ~6 weeks (Apr 2024 schedule)
• Building control: Shared St Albans & Watford service
• Other limits: Guideline 20–40% floorspace or 90–180 m³ over original house (2004 SPG Table 2, §7.1) — guidelines, not limits

See our St Albans area guide for housing types, prices and a local LCCL project.

Watford

• Local plan: Local Plan 2021–2038 (17 Oct 2022)
• Householder guidance: Residential Design Guide SPD (2014, amended 2016)
• Single-storey rear: 3 m terrace / 3.5 m semi or detached (8.4.6, 8.5.1)
• Two-storey rear: Unlikely beyond 3 m (8.8.1–8.8.2)
• Side extensions: Set back ≥ 1 m from front line; ≤ one-third of extended width; first floor ≥ 1 m from side boundary (8.7c, 8.8.2)
• Lofts and dormers: ≤ half roof height and width; ≥ 0.5 m below ridge and above eaves (8.12.3); front dormers generally inappropriate in CAs
• Basements: No householder basement policy
• Daylight / 45° test: Codified: 45° from centre of rear ground-floor habitable window in plan and elevation (7.3.11, 8.4.3); 25° for facing buildings (7.3.12)
• Article 4 directions: Street-specific in Nascot, Nascot Road, Civic Core, Watford Heath etc. (Part 1 A, C, D; Part 2 painting/fences)
• Pre-application advice: Written householder service, 4-week response
• Building control: Shared St Albans & Watford service
• Other limits: Separation 27.5 m back-to-back, 11 m to boundary, 10 m flank-to-flank; gardens 50/65/80/95 m² by bedrooms (7.3.15, 7.3.21)

See our Watford area guide for housing types, prices and a local LCCL project.

Hertsmere

• Local plan: Core Strategy (Jan 2013) + SADM Policies Plan (Nov 2016)
• Householder guidance: Planning and Design Guide Part E — Residential Extensions and Alterations (2006)
• Single-storey rear: ≤ 3.35 m beyond original rear wall (§1.c); eaves 3 m flat / 4 m pitched (§1.k–l)
• Two-storey rear: Governed by 45° line to neighbour's first-floor window (§3.e–f)
• Side extensions: ≤ half width of main house (§2.b, §4.c); two storey set back ≥ 1 m from front (§4.f), ≥ 1 m from boundary (2 m where significant gaps prevail)
• Lofts and dormers: Rear slope; ≤ 60% of roof face; 0.3 m from ridge and eaves; 0.5 m from boundaries (§6.f, §6.l); front dormers resisted (§6.g)
• Basements: No policy found
• Daylight / 45° test: Codified: 45° from nearest edge of neighbouring window (§1.b)
• Article 4 directions: The Royds, Potters Bar (Jul 2015: dormers, rooflights, windows, paving, walls); small-HMO across Potters Bar wards (made 23 Apr 2026)
• Pre-application advice: £192 written / £312 with meeting inc. VAT; 25 working days (Apr 2024 schedule)
• Building control: Hertfordshire Building Control Ltd (LABC)
• Other limits: Disproportionate-additions test, no % figure; gardens ≥ 60/80/100 m² by bedrooms (§1.e)

See our Hertsmere area guide for housing types, prices and a local LCCL project.

Welwyn Hatfield

• Local plan: Local Plan 2016–2036 (12 Oct 2023)
• Householder guidance: Supplementary Design Guidance (8 Feb 2005)
• Single-storey rear: Per 2005 guidance
• Two-storey rear: Per 2005 guidance
• Side extensions: ≥ 1 m from flank boundary (2005 §5)
• Lofts and dormers: Cheeks ≥ 1 m from flank wall; not above ridge (2005 §5)
• Basements: No policy found
• Daylight / 45° test: Not codified
• Article 4 directions: Per conservation area
• Pre-application advice: Per council schedule
• Building control: Hertfordshire Building Control Ltd (LABC)

See our Welwyn Hatfield area guide for housing types, prices and a local LCCL project.

Broxbourne

• Local plan: Local Plan 2018–2033 (23 Jun 2020)
• Householder guidance: Residential Design and Amenity SPG (Aug 2025)
• Single-storey rear: 60° test for ground-floor extensions
• Two-storey rear: 45° test
• Side extensions: ≥ 1 m off boundary and set back ≥ 1 m
• Lofts and dormers: ≤ half roof height/width in conservation areas
• Basements: No policy found
• Daylight / 45° test: Codified: 45° (two-storey) / 60° (ground floor); front extensions 45°
• Article 4 directions: Per conservation area
• Pre-application advice: Per council schedule
• Building control: Hertfordshire Building Control Ltd (LABC)

See our Broxbourne area guide for housing types, prices and a local LCCL project.

Method

Each council was researched from primary sources only: the adopted local plan, the current householder / residential extensions SPD or design guide, the council's Article 4 direction schedule, the published pre-application fee schedule and the building control service page. Where a document is dated we give the adoption date so you can judge how current it is. Emerging plans at examination are noted but their draft policies are not treated as adopted. We do not restate figures from third-party summaries, planning consultancies or other contractors. Items we could not verify against a council document were left out or marked 'per council schedule'.

Corrections: if you are a council officer or planning professional and spot an error or an update, email info@lcclconstruction.co.uk and we will amend the entry and re-date the page.

Why a builder keeps this list

LCCL Construction is a design and build company in Finchley N3. We take loft conversions, extensions, renovations and basements through planning, building control and construction under one contract, so we live inside these rules every week. As LABC Building Excellence Award Winners 2024 for Best Residential Extension in London, we keep this reference for our own designers first and publish it because clients, brokers and surveyors kept asking for it.

Need a design that fits your council's rules? Call 020 8037 7332, get an instant estimate or book a free consultation.

One team, one contract, one point of contact — from first sketch to handover.