Single-storey, double-storey, rear and side extension drawings for Aldenham West homes — measured to Hertsmere Borough Council's design guidance, delivered in days and revised free until your decision, with a free approval-odds check before you commit.
Hertsmere Borough Council granted 94% of the householder planning decisions it made in its latest published year — 7 points above the 87% England-wide householder average. Aldenham West contains Aldenham, Letchmore Heath, Patchetts Green and Delrow conservation areas (Aldenham designated 1973), so materials, fenestration and roof form are assessed against the appraisal, which is where a policy-literate drawing pack earns its keep. Its dominant interwar (1918–1939) and postwar (1945–1970) housing stock sets the design brief on most streets.
Class A and Class B set the thresholds — a rear dormer to 40m³ on a terrace or 50m³ on a semi or detached, and a single-storey rear extension to 3m on a terrace or 4m on a detached house — beyond which Hertsmere Borough Council needs a full application. In conservation areas such as Aldenham, Letchmore Heath and Patchetts Green and Delrow those rights are removed, so we confirm your exact address before a line is drawn. A validated householder application in Aldenham West is determined against an 8-week statutory target.
Aldenham (conservation area designated in 1973), Letchmore Heath (conservation area designated in 1969), Patchetts Green and Delrow (conservation area designated in 1998), Radlett North (conservation area designated in 1988), Round Bush (conservation area designated in 1978), Aldenham (civil parish within Aldenham West) and Hertsmere Meriden (civil parish within Aldenham West) — these are the Aldenham West pockets our drawings cover most. Heritage designations here include Aldenham, Letchmore Heath, Patchetts Green and Delrow, Radlett North and Round Bush. Hertsmere Borough Council weighs each proposal against Hertsmere Borough Council's adopted local plan and its householder design guidance, where the 2,100 homes here are 14% 1965-1972, 14% 1930-1939, 11% 1945-1954, which is what sets the realistic roof and rear-projection options. On roofs the borough is shallow-pitched roofs and integral garages typical of that period's building and hipped roofs with shallow pitches typical of 1930s building, over late-1960s and early-1970s houses (14% of 2,100 homes), 1930s semi-detached and detached houses (14%) and early postwar houses (11%).
Heritage designation is the single biggest variable in Aldenham West, and it is address-specific: Aldenham (conservation area designated in 1973), Letchmore Heath (conservation area designated in 1969), Patchetts Green and Delrow (conservation area designated in 1998), Radlett North (conservation area designated in 1988) and Round Bush (conservation area designated in 1978). Inside those boundaries permitted development is curtailed and Hertsmere Borough Council assesses materials, window detail and roof form against the area's own appraisal, so a scheme that would be waved through two streets away can need a full application here.
Beyond the designated areas, Aldenham West takes in Aldenham and Hertsmere Meriden. No Article 4 direction is recorded for Hertsmere Borough Council, but Aldenham West's 5 conservation areas still limit permitted development on those streets.
On stock, Aldenham West is late-1960s and early-1970s houses (14% of 2,100 homes), 1930s semi-detached and detached houses (14%) and early postwar houses (11%) — which is why shallow-pitched roofs and integral garages typical of that period's building and hipped roofs with shallow pitches typical of 1930s building govern what a loft or rear projection can realistically be. Hertsmere Borough Council decided 466 householder applications in the latest published year and granted 94%, with 49% issued inside the eight-week target. We work from the council's own published record.
The full build-period split for Aldenham West runs pre-1900 10% (220 homes), 1900-1918 5% (100 homes), 1919-1929 4% (90 homes), 1930-1939 14% (290 homes), 1945-1954 11% (240 homes), 1955-1964 8% (160 homes), 1965-1972 14% (300 homes), 1973-1982 2% (50 homes), 1983-1992 4% (80 homes), 1993-1999 7% (150 homes) and 2000-2008 10% (200 homes). That distribution is why pre-1900 detailing dominates the drawings here, and it is measured from council-tax records rather than assumed from the street name.
Hertsmere Borough Council also decides for Aldenham East, Bushey Heath, Bushey St James, Elstree and Shenley, so a decision in Aldenham West sits inside a wider pattern of decisions we track across the same authority — useful when an officer cites a precedent from the next area over.
Published figures for Aldenham West and Hertsmere Borough Council. These are the numbers that decide what is realistic on your street, so we work from them rather than from national averages.
| Measure | Aldenham West |
|---|---|
| Dwellings recorded | 2,100 |
| Built pre-1900 | 220 (10%) |
| Built 1900-1918 | 100 (5%) |
| Built 1919-1929 | 90 (4%) |
| Built 1930-1939 | 290 (14%) |
| Built 1945-1954 | 240 (11%) |
| Built 1955-1964 | 160 (8%) |
| Built 1965-1972 | 300 (14%) |
| Built 1973-1982 | 50 (2%) |
| Built 1983-1992 | 80 (4%) |
| Built 1993-1999 | 150 (7%) |
| Built 2000-2008 | 200 (10%) |
| Built before 1919 | 15% |
| Built 1919–1939 | 18% |
| Built 1945–2008 | 56% |
| Conservation areas in Aldenham West | 5 (Aldenham, Letchmore Heath…) |
| Conservation areas district-wide | 16 |
| Article 4 directions recorded | 0 |
| Householder applications decided | 466 |
| Householder applications granted | 94% |
| Decided within 8 weeks | 49% |
Dwelling stock from VOA council-tax data at 31 March 2025; conservation-area and Article 4 counts from planning.data.gov.uk (MHCLG); decision figures are Hertsmere Borough Council's own, from MHCLG live table PS2 for the year to 31 March 2026.
Aldenham West homes come in a handful of recurring shapes, and each one points to a different extension. The borough is built largely from late-1960s and early-1970s houses (14% of 2,100 homes), 1930s semi-detached and detached houses (14%) and early postwar houses (11%), so a Victorian terrace usually wants a rear or side-return infill, while an interwar semi has room for a wider single-storey wrap or a two-storey side addition. Hertsmere Borough Council judges every one of them against Hertsmere Borough Council's adopted local plan and its householder design guidance, weighing footprint, height and the impact on the house next door before it looks at the elevations.
That is why the drawings decide the outcome. We set the extension depth against the permitted-development limits precisely, keep the eaves and ridge within the allowances, and plot the 45-degree daylight lines to the neighbours' windows so the case officer can see the amenity test is passed. Aldenham West contains Aldenham, Letchmore Heath, Patchetts Green and Delrow conservation areas (Aldenham designated 1973), so materials, fenestration and roof form are assessed against the appraisal, so we design around it from the first sketch rather than discover it at validation.
Aldenham West also protects whole streets — Aldenham, Letchmore Heath, Patchetts Green and Delrow, Radlett North and Round Bush among them. No Article 4 direction is recorded for Hertsmere Borough Council, but Aldenham West's 5 conservation areas still limit permitted development on those streets. On designated land the larger-home extension route and most side extensions stop being permitted development, so we confirm your address against those layers before drawing a line.
Plenty of Aldenham West extensions are permitted development and need no planning application — a single-storey rear extension within the depth and height limits is the common case. You will normally need to apply to Hertsmere Borough Council if any of these apply:
We draw the footprint, the ridge and eaves heights and the neighbours' daylight on the page — the relationships Hertsmere Borough Council's officers weigh first — and submit a validation-complete pack, whether that is a lawful development certificate, a prior-approval notification or a full householder application.
Below is Hertsmere Borough Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Hertsmere Borough Council granted 94% of its householder applications in the year to 31 March 2026, and Aldenham shapes what is approved here. A complete, policy-literate extension pack anticipates those pressure points before submission, which is why professionally drawn applications are decided faster and refused less often than DIY ones.
Source: MHCLG planning application statistics (householder decisions, England, 1 April 2025 - 31 March 2026). Compare every borough on our London approval-rate league table.
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.
Across Aldenham, Letchmore Heath and Patchetts Green and Delrow, the extension that lands most often is the single-storey rear addition — a glazed kitchen-diner across the back of the house, kept within the permitted-development depth or taken to a full application where the ground floor wants more. On the borough's late-1960s and early-1970s houses (14% of 2,100 homes), a side-return infill frequently pairs with it to square off the plan; on wider early postwar houses (11%), a two-storey side or rear extension can add a bedroom above without swallowing the garden.
The 2,100 homes here are 14% 1965-1972, 14% 1930-1939, 11% 1945-1954, which is what sets the realistic roof and rear-projection options. We size the extension to the amenity and daylight tests, match the roof and materials to the host house, and keep enough garden to satisfy Hertsmere Borough Council's space standards — so the scheme answers the borough's questions before an objection can raise them. Where permitted-development rights are used up or removed, we prepare the householder application to the council's extension design guidance instead.
We draw extensions on every street in the borough. A few of the neighbourhoods where Aldenham West projects come up most often:
Extension drawings for Aldenham's conservation area designated in 1973 — footprint-checked, daylight-tested and drawn to Hertsmere Borough Council's guidance.
Extension drawings for Letchmore Heath's conservation area designated in 1969 — footprint-checked, daylight-tested and drawn to Hertsmere Borough Council's guidance.
Extension drawings for Patchetts Green and Delrow's conservation area designated in 1998 — footprint-checked, daylight-tested and drawn to Hertsmere Borough Council's guidance.
Extension drawings for Radlett North's conservation area designated in 1988 — footprint-checked, daylight-tested and drawn to Hertsmere Borough Council's guidance.
Extension drawings for Round Bush's conservation area designated in 1978 — footprint-checked, daylight-tested and drawn to Hertsmere Borough Council's guidance.
Extension drawings for Aldenham's civil parish within Aldenham West — footprint-checked, daylight-tested and drawn to Hertsmere Borough Council's guidance.
The right extension in Aldenham West depends on your house type and how much garden you can give up. This is how the main options compare on planning route and what they add.
| Extension type | Permitted development? | What it adds | What Hertsmere Borough Council checks |
|---|---|---|---|
| Single-storey rear | Often, within 3m/4m depth (6m/8m via prior approval) | Bigger kitchen-diner across the back | Depth, height, neighbour daylight (45°) |
| Side-return infill | Sometimes, if within width and height limits | Squares off an L-shaped ground floor | Width vs the original house, glazing to boundary |
| Two-storey rear/side | No — full application | Extra bedroom or bathroom above | Bulk, overlooking, 7m rear-boundary gap |
| Wraparound (rear + side) | No — full application | Whole-width open-plan ground floor | Combined footprint and garden retained |
Route depends on your street — conservation areas such as Aldenham and Letchmore Heath and Article 4 directions can remove permitted-development rights.
A fixed process built around how Hertsmere Borough Council validates and decides householder extension applications — most drawings are submission-ready within seven days of survey.
Tell us your Aldenham West postcode and house type. We confirm your conservation and Article 4 status, how much permitted-development depth you have left, and score your odds against live Hertsmere Borough Council decisions.
We measure the existing footprint, floor and eaves levels, boundary distances and the neighbours' window positions — the numbers the depth limits and daylight tests depend on.
Chartered designers develop the single-storey, two-storey or side extension to your brief, drawn inside the permitted-development limits or to Hertsmere Borough Council's extension design guidance.
We submit the certificate, prior-approval notice or application, manage validation and case-officer queries, and revise the drawings free until Hertsmere Borough Council issues its decision.
Not always. A single-storey rear extension up to 3 metres deep on a terrace or semi, or 4 metres on a detached house, and no higher than 4 metres, is usually permitted development. In Aldenham West you will need to apply to Hertsmere Borough Council for two-storey extensions, side extensions wider than half the house, anything forward of the front wall, deeper rear extensions under the larger-home prior-approval route, and any extension in a conservation area such as Aldenham and Letchmore Heath.
Standard permitted development allows 3 metres on a terraced or semi-detached house and 4 metres on a detached one. The larger-home extension scheme can double that to 6 or 8 metres, but it needs a prior-approval notification to Hertsmere Borough Council and a neighbour-consultation period, and it does not apply on designated land such as Aldenham West's conservation areas. We confirm which route your property qualifies for before drawing.
Two-storey and double-storey extensions almost always need a full householder application to Hertsmere Borough Council, because they fall outside permitted development on most homes. The council looks closely at bulk, overlooking of neighbours and the 7-metre gap a two-storey rear extension must keep from the rear boundary. We design to those tests and show the daylight and privacy angles on the drawings. This applies to your Aldenham West address specifically.
A householder planning application in Aldenham West runs to a statutory eight-week target, a larger-home prior-approval notification to around six weeks including the neighbour-consultation period, and a lawful development certificate to eight weeks. Incomplete submissions stall at validation, so we submit a complete pack and manage officer queries to keep the decision on schedule. Hertsmere Borough Council is the decision-maker.
Yes — planning permission and building regulations are separate consents, and almost every extension needs both. Planning governs whether you can build it; building control governs how it is built, covering structure, insulation, drainage and fire safety. We prepare the building-regulations drawings alongside the planning set so Hertsmere Borough Council's building control or an approved inspector can sign the work off. This applies to your Aldenham West address specifically.
Every house and brief is different, so we price each Aldenham West extension individually and send a fixed, no-obligation quote back within one working day. It covers the full drawing pack with free revisions until Hertsmere Borough Council approves, and we tell you upfront whether your extension qualifies as permitted development. Call 020 7864 7245 to get started.
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Same fixed quotes, same fast drawings — wherever your project is.