Annexe and granny-flat drawings for Elstree homes — designed to stay ancillary to the main house rather than become a separate dwelling, drawn to Hertsmere Borough Council's policies, delivered in days and revised free until your decision.
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. Elstree contains the Elstree Village conservation area (Elstree Village designated 1976), so materials, fenestration and roof form are assessed against the appraisal, which is where a policy-literate drawing pack earns its keep. Its dominant 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 Elstree Village those rights are removed, so we confirm your exact address before a line is drawn. A validated householder application in Elstree is determined against an 8-week statutory target.
Elstree Village (conservation area designated in 1976) and Elstree and Borehamwood (civil parish within Elstree) — these are the Elstree pockets our drawings cover most. Heritage designations here include Elstree Village. Hertsmere Borough Council weighs each proposal against Hertsmere Borough Council's adopted local plan and its householder design guidance, where the 2,010 homes here are 21% 1955-1964, 14% 1945-1954, 12% 1983-1992, which is what sets the realistic roof and rear-projection options. On roofs the borough is shallow gabled roofs typical of that period's building and simple gabled and hipped roofs typical of early postwar building, over late-1950s and early-1960s houses (21% of 2,010 homes), early postwar houses (14%) and 1980s estate houses (12%).
Heritage designation is the single biggest variable in Elstree, and it is address-specific: Elstree Village (conservation area designated in 1976). 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, Elstree takes in Elstree and Borehamwood. No Article 4 direction is recorded for Hertsmere Borough Council, but Elstree's 1 conservation area still limit permitted development on those streets.
On stock, Elstree is late-1950s and early-1960s houses (21% of 2,010 homes), early postwar houses (14%) and 1980s estate houses (12%) — which is why shallow gabled roofs typical of that period's building and simple gabled and hipped roofs typical of early postwar 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 Elstree runs pre-1900 5% (110 homes), 1900-1918 2% (40 homes), 1919-1929 3% (70 homes), 1930-1939 4% (80 homes), 1945-1954 14% (280 homes), 1955-1964 21% (420 homes), 1965-1972 11% (230 homes), 1973-1982 11% (220 homes), 1983-1992 12% (250 homes), 1993-1999 3% (60 homes) and 2000-2008 2% (50 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, Aldenham West, Bushey Heath, Bushey St James and Shenley, so a decision in Elstree 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 Elstree 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 | Elstree |
|---|---|
| Dwellings recorded | 2,010 |
| Built pre-1900 | 110 (5%) |
| Built 1900-1918 | 40 (2%) |
| Built 1919-1929 | 70 (3%) |
| Built 1930-1939 | 80 (4%) |
| Built 1945-1954 | 280 (14%) |
| Built 1955-1964 | 420 (21%) |
| Built 1965-1972 | 230 (11%) |
| Built 1973-1982 | 220 (11%) |
| Built 1983-1992 | 250 (12%) |
| Built 1993-1999 | 60 (3%) |
| Built 2000-2008 | 50 (2%) |
| Built before 1919 | 7% |
| Built 1919–1939 | 7% |
| Built 1945–2008 | 75% |
| Conservation areas in Elstree | 1 (Elstree Village) |
| 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.
Councils do not decide annexes on square metres. They decide whether, once built, the accommodation forms part of one planning unit with the main house or a second one beside it. Hertsmere Borough Council looks at whether the garden is shared or divided, whether the annexe has its own street access and address, whether the occupier could live there entirely independently, and whether the two households would function as one. That is the whole case, and it is made or lost on the layout.
Elstree is largely late-1950s and early-1960s houses (21% of 2,010 homes), early postwar houses (14%) and 1980s estate houses (12%), which shapes the realistic options: converting part of the existing house, extending it, or building a detached unit in the garden. A detached annexe can sometimes sit under Class E as an outbuilding incidental to the enjoyment of the dwellinghouse — but sleeping accommodation is generally not "incidental", so a garden annexe with a bedroom usually needs its own permission rather than relying on outbuilding rights.
In Elstree's conservation areas — including Elstree Village — a garden building is also judged on its effect on the character of the area, which limits height and footprint before the use question is reached. No Article 4 direction is recorded for Hertsmere Borough Council, but Elstree's 1 conservation area still limit permitted development on those streets.
An annexe almost always needs an application to Hertsmere Borough Council. Expect one where any of these apply:
We plan the annexe so its relationship to the main house is visible on the page — shared garden, connected access, a layout that reads as one household — and set out the case Hertsmere Borough Council has to test, rather than leaving the officer to assume the worst.
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 Elstree Village shapes what is approved here. Annexe applications are decided on use as much as design, so the supporting case matters as much as the elevations.
Source: MHCLG planning application statistics (householder decisions, England, 1 April 2025 - 31 March 2026). Compare every borough on our London approval-rate league table.
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Across Elstree Village and Elstree and Borehamwood, the annexes that succeed keep one shared garden, take access past the main house rather than from the street, and are modest against the host building — single storey where the plot is overlooked, and set back from boundaries. On late-1950s and early-1960s houses (21% of 2,010 homes), converting an integral garage or a rear ground floor is often approved more readily than a detached garden unit, because the ancillary relationship is self-evident.
Elstree contains the Elstree Village conservation area (Elstree Village designated 1976), so materials, fenestration and roof form are assessed against the appraisal. Where Hertsmere Borough Council grants permission, it commonly attaches a condition tying occupation of the annexe to the main dwelling. That condition is not a problem to be avoided — it is usually the mechanism that makes approval possible, and we draft the application on that basis rather than pretending the annexe is something it is not.
We draw annexes across Elstree. A few of the areas where multigenerational schemes come up most often:
Annexe and granny-flat drawings for Elstree Village — conservation area designated in 1976 — planned to stay ancillary and drawn to Hertsmere Borough Council's policies.
Annexe and granny-flat drawings for Elstree and Borehamwood — civil parish within Elstree — planned to stay ancillary and drawn to Hertsmere Borough Council's policies.
Three similar buildings, three different consents. This is what separates them.
| What you build | Planning status | Key test | What Hertsmere Borough Council checks |
|---|---|---|---|
| Garden room, no sleeping space | Often Class E permitted development | Incidental to the house | Height, footprint, boundary position |
| Annexe used by the household | Full application, usually with a tie condition | Ancillary use | Shared garden and access, layout |
| Self-contained unit, own access | New dwelling — full application | Separate planning unit | Policy on new homes, amenity, parking |
| Converted garage or ground floor | Often permitted, use still assessed | Whether use changes | Independence of the accommodation |
| Annexe on designated land | Full application | Designation | Character and appearance |
The ancillary/separate-dwelling distinction comes from section 55 of the Town and Country Planning Act 1990; outbuilding limits from the GPDO 2015, Schedule 2, Part 1, Class E.
A fixed process built around how Hertsmere Borough Council tests the use question as well as the design.
Tell us who the annexe is for and where it would sit on the plot. We confirm designation status and tell you honestly whether the scheme reads as ancillary or as a separate dwelling in Elstree.
We measure the plot, the existing house and the access route, so the shared-garden and shared-access case can be drawn rather than asserted.
Chartered designers develop the annexe to your brief, with the layout, access and garden relationship arranged to support the ancillary case under Hertsmere Borough Council's policies.
We submit the application with a supporting statement on use, manage validation and case-officer queries, and revise free until Hertsmere Borough Council decides.
Almost always. Sleeping accommodation is generally not "incidental" to the enjoyment of a house, so it falls outside the outbuilding permitted-development right, and any annexe that could function independently raises a change-of-use question under section 55. In Elstree we prepare a full application to Hertsmere Borough Council and make the ancillary case explicitly rather than hoping it is not asked.
A shared garden rather than a divided one, access through the main property rather than a separate street entrance, occupation by a member of the same household, and a physical and functional relationship with the main house. Hertsmere Borough Council weighs those together — no single feature decides it, but a separate front door and a fenced-off garden together usually settle it against you. This applies to your Elstree address specifically.
Yes, subject to permission. A detached garden annexe is assessed on its scale against the plot, its effect on neighbours and the character of the area, and then on the use question. Keeping it single storey, set in from boundaries and served off the shared garden gives it the best prospect in Elstree, particularly near designated areas such as Elstree Village. Hertsmere Borough Council is the decision-maker.
Commonly, yes — a condition tying occupation of the annexe to the main dwelling, so it cannot be sold or let separately. That is normally what makes approval possible, because it removes the concern that a new independent home is being created without going through housing policy. The condition runs with the land, so it matters at resale, and we explain the implications before you commit. This applies to your Elstree address specifically. Hertsmere Borough Council is the decision-maker.
Yes. A new annexe is new habitable accommodation, so structure, fire escape, insulation and ventilation all apply, and a detached annexe close to a boundary raises fire-spread requirements as well. Planning and building control are separate consents with separate submissions — we prepare both so the approved design is the one that can actually be built. This applies to your Elstree address specifically. Hertsmere Borough Council is the decision-maker.
A householder application runs to an eight-week statutory target; where the council treats the annexe as creating a new unit it becomes a minor application with a thirteen-week target instead. Which route applies depends on how the use is characterised, which is precisely why the ancillary case is worth making properly at the outset. This applies to your Elstree address specifically. Hertsmere Borough Council is the decision-maker.
We quote each Elstree annexe individually, because plot, access and whether you are converting or building new all change the work, and send a fixed, no-obligation quote within one working day. It covers the full drawing pack and supporting statement, with free revisions until Hertsmere Borough Council approves. Call 020 7864 7245 to start.
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