A two storey extension adds a bedroom and bathroom above the kitchen you are already building, and it follows tighter rules than a single storey one. This page sets out the Class A limits letter by letter, the drawings that prove them, and what changes in a conservation area.
Two-storey extension (planning drawings)
Fixed in writing after a free assessment of your property. Council planning fees are separate.
Prices include VAT. Checked 14 October 2026.
The limits sit in Class A of Part 1, Schedule 2 of the 2015 General Permitted Development Order (GPDO). Every paragraph below must be met for a two storey extension to be permitted development, and the house must be a dwellinghouse rather than a flat.
| Paragraph | What it says | What it means for the drawings |
|---|---|---|
| A.1(h)(i) | More than one storey: no more than 3 m beyond the rear wall of the original dwellinghouse | Dimension the depth from the original rear wall, not from today's back wall |
| A.1(h)(ii) | More than one storey: not within 7 m of any boundary of the curtilage opposite the rear wall | Dimension the gap from the new rear wall to each boundary opposite it on the block plan |
| A.1(c) and (d) | The extension may not rise above the highest part of the existing roof, and its eaves may not be higher than the existing eaves | Section and side elevation that show ridge and eaves against the existing house |
| A.1(i) | Within 2 m of a boundary, the eaves of the enlarged part may not exceed 3 m | Eaves height dimensioned wherever the wall is within 2 m of the boundary |
| A.1(e) | No enlargement beyond the principal elevation, or beyond a side wall that fronts a highway | Front elevation and block plan showing nothing projects forward |
| A.1(b) | Buildings other than the original house may not cover more than 50% of the curtilage, excluding the ground area of the original house | Block plan with the plot area and the area of earlier extensions and outbuildings |
| A.1(j) | An enlargement beyond a side wall may not be higher than 4 m, may not have more than a single storey and may not be wider than half the original house | A first floor addition that reaches past a side wall is outside Class A on this paragraph |
| A.1(ja) | The total enlargement, meaning the new part plus any existing enlargement it will join, must stay inside the limits in A.1(e) to (j) | Existing plans that record every earlier extension, with dates where known |
| A.1(k) | No verandah, balcony or raised platform, and no alteration to any part of the roof of the house. The MHCLG guidance says that where the new roof joins the existing roof, the alteration to the old roof must meet Class B or C | Roof plan and section at the join. The guidance says a Juliet balcony with no platform would normally be permitted development |
| A.3(a) to (c) | Materials of a similar appearance; any upper floor side window obscure-glazed and non-opening unless the opening part is more than 1.7 m above the floor; roof pitch to match the original so far as practicable | Annotate materials, window glazing and the pitch on the elevations |
| A.2(c) | On article 2(3) land, which includes conservation areas, no extension of more than one storey beyond the rear wall | Route changes to a planning application. A side extension and cladding in stone, artificial stone, pebble dash, render, timber, plastic or tiles are also removed by A.2 |
Source: GPDO 2015, Schedule 2, Part 1, Class A and article 2, read 15 October 2026, with the MHCLG householder technical guidance (last updated 10 September 2019). The guidance reads the side wall limit as 'less than 4 metres' where the order says 'exceed 4 metres': the order text governs. An Article 4 direction or a planning condition can remove these rights.
A 3 metre two storey extension is permitted development only if 7 metres remain between the new rear wall and the boundary opposite it. Take the garden length from the original rear wall, subtract the extension depth and compare the remainder with 7. A garden of 10 metres or more from the original rear wall passes this test at the full 3 metres, where the boundary runs parallel to the rear wall. We run that sum on the measured survey before any design starts, and the block plan carries the dimension so the officer can check it.
This example is arithmetic, not a real job, and the dimensions are assumed. A semi-detached house has a rear garden 9.4 m long, measured from the original rear wall to the fence behind. The owner asks for a two storey extension 3 m deep.
The extension would leave 6.4 m to the rear boundary, which is inside the 7 m line, so it is not permitted development. The deepest two storey extension that keeps 7 m clear is 2.4 m (9.4 m minus 7 m). Everything else in the table could be met, but the 7 m test decides the route: either a 2.4 m two storey extension under permitted development, or a planning application for the full 3 m on its merits.
A second assumption changes the answer again. If an earlier owner built a single storey back addition 3.5 m deep that was not part of the original house, a first floor on top would fail A.1(h)(i) through the total enlargement test in A.1(ja): the total enlargement would have more than one storey and project more than 3 m. The MHCLG guidance gives a similar example for a detached house. The existing plans must therefore show every earlier addition.
A two storey scheme needs the standard planning sheets plus the dimensions that prove the route. These scales are our working practice, and your council's validation list may add to them.
| Sheet | Typical scale | What it shows for a two storey extension | Why the council or building control asks |
|---|---|---|---|
| Location plan | 1:1250 | Site edged red, adjoining land you own edged blue, two named roads, north point | Identifies the land. The Planning Portal describes a standard metric scale, typically 1:1250 or 1:2500 |
| Block plan | 1:200 or 1:500 | Footprint, the 7 m dimension to each boundary opposite the rear wall, boundaries, other buildings | Tests A.1(b) and A.1(h)(ii) and shows the relationship to neighbours |
| Existing floor plans and elevations | 1:50 or 1:100 | The house as it stands, with every earlier extension marked and the original rear wall identified | Fixes the baseline for depth, A.1(ja) and the height limits |
| Proposed ground and first floor plans | 1:50 or 1:100 | New rooms, stair, window positions and the depth dimensioned from the original rear wall | Shows use, layout and overlooking |
| Proposed elevations, all sides affected | 1:50 or 1:100 | Materials, roof pitch, eaves and ridge against the existing house, upper floor window glazing | Tests A.1(c), (d), (i) and A.3(a) to (c), and the effect on the street and gardens |
| Sections | 1:50 | Floor levels, ridge and eaves heights, and a line to the neighbour's nearest window where local policy tests daylight | The daylight and outlook test in the council's own guidance |
| Roof plan | 1:50 or 1:100 | Pitch, valleys, rooflights and the join to the existing roof | Shows no part rises above the existing ridge and that the roof is not altered beyond the extension |
| Structural layout and details (building regulations) | 1:50 and 1:20 | Foundations, steels, first floor joists and the load path through the old walls | Building control checks the structure and thermal build-ups separately from planning |
Sources: Planning Portal, plans and drawings, read 14 October 2026; GPDO Class A as above. The Planning Portal gives location plans typically at 1:1250 or 1:2500 and site plans at 1:200 or 1:500. Local lists differ: see our planning application drawings page for each borough's checklist.
Where permitted development is not available, the council weighs the scheme against its adopted local plan and its own residential design guidance. Three tests recur: daylight and outlook for the neighbour's nearest windows, overlooking from the new upper floor, and how the extension reads from the street and the gardens behind. The depth, set-back and height that pass differ by borough, so we read the current adopted policy for your borough before the first sketch.
The Class A conditions also work as a design checklist when an application is needed. Upper floor side windows that are obscure-glazed and non-opening below 1.7 m answer the overlooking question; matching materials and a matching roof pitch answer the street question. A set-back at first floor or a lower ridge are the usual devices to keep a two storey form subordinate to the house.
Where the numbers pass the permitted development limits, a certificate of lawful development is optional proof, and the council has eight weeks from a valid application to decide it (DMPO article 39(10)). Our lawful development certificate guide sets out the evidence it needs.
Householder approval rates ran from 68.0% to 98.6% between boroughs in 2025-26, so the same two storey scheme faces different odds depending on where the house stands.
| Borough | Householder decisions, 2025-26 | Approval rate | Appeals allowed (5 years) |
|---|---|---|---|
| Barking and Dagenham | 406 | 68.0% | 30.0% |
| Greenwich | 647 | 77.6% | 42.9% |
| Bromley | 1,538 | 79.0% | 37.6% |
| Richmond upon Thames | 1,362 | 81.7% | 44.9% |
| Merton | 769 | 92.2% | 35.6% |
| Hammersmith and Fulham | 560 | 98.6% | 36.5% |
Approval: MHCLG district planning application statistics (PS1/PS2), householder developments, financial year 2025-26; the London figure is 85.6% of 24,758 decisions. Appeals: Planning Inspectorate casework, householder appeals, five years to 30 June 2026; London 39.9%, England 34.4%. These are all householder applications, not two storey schemes alone. The full borough table is on our house extension plans page.
An upper floor puts load on foundations and walls that a ground floor addition does not, so the structural design runs alongside the planning drawings. A first floor over an old single storey back addition needs its walls checked, because they may not carry another floor.
The Party Wall etc. Act 1996 can apply in three ways. Section 1 covers a new wall on the line of junction, with notice at least one month before the work starts. Section 2 covers work to an existing party wall, and a party structure notice must be served at least two months before the work begins (section 3). Section 6 covers excavation within 3 metres of a neighbouring building that goes deeper than its foundations, and within 6 metres where it meets a 45 degree plane drawn down from them, with notice at least one month before. These are separate from planning permission.
The Community Infrastructure Levy guidance says an extension of less than 100 square metres that is not a new dwelling is generally exempt under the minor development exemption, and an extension to your main home can claim the residential extension exemption, but the claim must reach the council before work starts. In London the Mayor's levy applies in every borough and a borough may also charge its own, so check the charging schedule for your address; the exemptions above still apply.
These are common errors that turn a permitted development scheme into an application, or make an application harder to validate.
We measure the house as it stands and work back to the original walls, because the allowances run from the original rear wall and any earlier addition changes both the depth and the route.
We run the depth, 7 m, height, eaves and designation tests, then recommend a certificate where the scheme is permitted development and an application where it is not.
Before the full pack, we test the scheme against the neighbouring windows and the council's current daylight guidance so a conflict is found on paper.
Plans, elevations, sections and the location and block plans, prepared to the council's validation list, then submitted, with the drawings revised free until the council decides.
Once consent is in hand, the same survey feeds the building regulations drawings and the structural calculations your builder prices from.
The price panel on this page shows the starting price for the two storey planning set, and the fee for the set with building regulations drawings and structural calculations. Both include VAT. Council planning fees are separate and paid to the council.
Tell us about your project and get a fixed, no-obligation quote back within one working day. If you don't need planning permission at all, we'll tell you that too — for free.
Sometimes. A two storey rear extension is permitted development if it goes no more than 3 m beyond the original rear wall, stays at least 7 m from each boundary opposite that wall, and keeps within the height, eaves and materials limits in Class A. In a conservation area it needs an application. A certificate of lawful development is optional proof for the council's view.
Under permitted development, 3 m beyond the rear wall of the original house, provided at least 7 m remain to the boundary opposite the rear wall. With planning permission the limit is whatever the council accepts on its merits, which depends on the neighbours' windows, the roof and the street, measured against its adopted policy and design guidance.
No. The larger home extension route, with its 6 m and 8 m depths, applies only to single storey rear extensions under paragraph A.1(g). A two storey rear extension is either within the 3 m and 7 m limits of A.1(h) or needs a planning application. Prior approval also lets neighbours object, which brings in an amenity assessment.
Almost certainly. Paragraph A.1(j) allows an enlargement beyond a side wall only if it has a single storey, is no higher than 4 m and is no wider than half the width of the original house. A two storey enlargement beyond a side wall is outside Class A on the storey limit, so a householder application is the route.
Only with planning permission. Paragraph A.2 takes any extension of more than one storey beyond the rear wall, and any side extension, out of permitted development on article 2(3) land, which includes conservation areas. The council judges the scheme on its design and its effect on the character of the area, so materials, roof form and detailing carry weight.
It is a daylight test that some councils write into their own guidance, not a national law and not part of the permitted development order. A line is drawn at an angle from the neighbour's nearest window, and an extension that crosses it may take too much light. The angle and the window it is measured from differ between boroughs, so read your council's current guidance.
Under Class A condition A.3(b), an upper floor window in a side elevation must be obscure-glazed and non-opening unless the opening part is more than 1.7 m above the floor of the room. This protects the neighbour from overlooking. A planning application can propose different glazing, but the council will look closely at windows facing a neighbour at close range.
Possibly. The Party Wall etc. Act 1996 can apply if you build a wall on the boundary (section 1, notice at least one month before), cut into or raise a shared wall (section 2, a party structure notice at least two months before) or excavate within 3 m of a neighbouring building below its foundations, or within 6 m where the dig meets the 45 degree plane (section 6). It is separate from planning.
Usually not. Gov.uk guidance says development of less than 100 square metres is generally exempt, unless it creates a new dwelling. A larger extension to your own main home can claim the residential extension exemption, but the claim must reach the council before work starts. In London the Mayor's levy applies in every borough, and a borough may also charge its own.
The council has eight weeks from receipt of a valid application to decide a non-major application, unless you agree a longer period in writing (DMPO article 34(2)). Excluding applications decided under an agreed extension of time or planning performance agreement, Redbridge decided 95.5% of its householder applications within eight weeks in 2025-26, and Barking and Dagenham 100%. Allow extra time for the drawings beforehand and for any amendments the officer requests.
Local drawings tuned to each council's design guidance, with live borough approval rates. Pick your area:
Two storey extension plans in Ealing — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Ealing →Two storey extension plans in Wandsworth — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Wandsworth →Two storey extension plans in Bromley — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Bromley →Two storey extension plans in Barnet — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Barnet →Two storey extension plans in Harrow — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Harrow →Two storey extension plans in Sutton — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Sutton →Two storey extension plans in Richmond upon Thames — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Richmond upon Thames →Two storey extension plans in Kingston upon Thames — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Kingston upon Thames →Two storey extension plans in Camden — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Camden →Two storey extension plans in Islington — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Islington →Two storey extension plans in Haringey — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Haringey →Two storey extension plans in Enfield — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Enfield →Two storey extension plans in Waltham Forest — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Waltham Forest →Two storey extension plans in Hillingdon — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Hillingdon →Two storey extension plans in Hounslow — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Hounslow →Two storey extension plans in Hammersmith and Fulham — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Hammersmith and Fulham →Two storey extension plans in Kensington and Chelsea — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Kensington and Chelsea →Two storey extension plans in Westminster — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Westminster →Two storey extension plans in Merton — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Merton →Two storey extension plans in Lambeth — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Lambeth →Two storey extension plans in Croydon — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Croydon →Two storey extension plans in Hackney — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Hackney →Two storey extension plans in Newham — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Newham →Two storey extension plans in Redbridge — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Redbridge →Two storey extension plans in Barking and Dagenham — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Barking and Dagenham →Two storey extension plans in Havering — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Havering →Two storey extension plans in Greenwich — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Greenwich →Two storey extension plans in Lewisham — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Lewisham →Two storey extension plans in Bexley — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Bexley →Two storey extension plans in Southwark — drawn to the 3m projection and 7m boundary rules, checked for overlooking. Free revisions until approval.
View Southwark →Answer five quick questions and get a free planning score for your exact address — instantly. Then, if you want the full picture, unlock the detailed analysis: your council's live approval rates, local precedents, constraints on your street and a step-by-step route to permission.