Side-return infill drawings for Aldenham West terraces — the glazed extension that fills the redundant side alley and opens up the kitchen, drawn to Hertsmere Borough Council's guidance, delivered in days and revised free until your decision, with a free approval-odds check first.
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.
The side return is the classic terrace fix, and Aldenham West has the stock for it — 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%), and the Victorian and Edwardian versions almost all have an L-shaped back addition with a wasted alley beside it. Fill that alley and the dark galley kitchen becomes a bright, square room the full width of the house. Hertsmere Borough Council judges the infill against Hertsmere Borough Council's adopted local plan and its householder design guidance, and because it runs along the party boundary, the neighbour relationship is read before the design.
That boundary is where the drawings earn their keep. We set the infill wall on or up to the line, keep the roof — usually a glazed lantern or a shallow pitch tying into the existing back-addition slope — below the neighbour's first-floor windows, and detail the rainwater and party-wall junction so the build is watertight and the Party Wall Act is satisfied. 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 resolve it on the section rather than leave it to the case officer.
Many of Aldenham West's terraces sit in conservation areas — Aldenham, Letchmore Heath, Patchetts Green and Delrow, Radlett North and Round Bush among them — where a side extension is no longer permitted development. No Article 4 direction is recorded for Hertsmere Borough Council, but Aldenham West's 5 conservation areas still limit permitted development on those streets. We confirm the designation before a line is drawn.
Some single-storey side returns in Aldenham West are permitted development, but the width and boundary make an application more likely than for a straight rear extension. You will normally need to apply to Hertsmere Borough Council if any of these apply:
We draw the infill wall on the boundary, the glazed roof below the neighbour's windows and the party-wall junction on the page — the details Hertsmere Borough Council's officers and your neighbour both check — and submit a validation-complete pack, whether that is a lawful development certificate 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. Side returns hinge on width, roof glazing and the party boundary, so a pack that resolves those details upfront is decided faster and refused less often than a DIY submission.
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 approved side return is a single-storey infill roofed with a glazed lantern or roof light to pull daylight deep into the plan, its flank wall built on the boundary and finished to match the host brick. On the borough's late-1960s and early-1970s houses (14% of 2,100 homes), this is frequently the single biggest gain in usable ground-floor space, and where it stays within the width and height limits it can proceed under permitted development or a lawful development certificate.
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 keep the glazed roof below the neighbour's cill line, set the gutter and the party-wall flashing so water and maintenance are designed in, and — where owners want the full open-plan room — pair the infill with a rear extension as a single wraparound application. That way Hertsmere Borough Council sees one coherent scheme rather than two overlapping ones.
We draw side-return infills on every terraced street in the borough. A few of the neighbourhoods where Aldenham West side returns come up most often:
Side return extension drawings for Aldenham's conservation area designated in 1973 — width-checked, party-wall detailed and drawn to Hertsmere Borough Council's guidance.
Side return extension drawings for Letchmore Heath's conservation area designated in 1969 — width-checked, party-wall detailed and drawn to Hertsmere Borough Council's guidance.
Side return extension drawings for Patchetts Green and Delrow's conservation area designated in 1998 — width-checked, party-wall detailed and drawn to Hertsmere Borough Council's guidance.
Side return extension drawings for Radlett North's conservation area designated in 1988 — width-checked, party-wall detailed and drawn to Hertsmere Borough Council's guidance.
Side return extension drawings for Round Bush's conservation area designated in 1978 — width-checked, party-wall detailed and drawn to Hertsmere Borough Council's guidance.
Side return extension drawings for Aldenham's civil parish within Aldenham West — width-checked, party-wall detailed and drawn to Hertsmere Borough Council's guidance.
Whether a side return in Aldenham West needs permission comes down to width, storeys and whether the street is designated. This is how the cases compare.
| Side return type | Permitted development? | What it gains | What Hertsmere Borough Council checks |
|---|---|---|---|
| Single-storey infill, within limits | Often yes, if under half the house width | Full-width kitchen-diner | Width, 4m height, roof glazing |
| Single-storey, over half width | No — full application | Wider room, more light | Boundary treatment, neighbour amenity |
| Two-storey side return | No — full application | Room above as well as below | Bulk, overlooking, terrace rhythm |
| Wraparound (side + rear) | No — full application | L-shaped open-plan ground floor | Combined footprint, garden retained |
In conservation areas such as Aldenham and Letchmore Heath, side extensions are not permitted development and always need a full application.
A fixed process built around how Hertsmere Borough Council validates and decides side-return applications — most drawings are submission-ready within seven days of survey.
Send us your Aldenham West postcode and terrace type. We confirm your conservation and Article 4 status, whether the infill stays within the side-extension width limit, and score your odds against live Hertsmere Borough Council decisions.
We measure the side alley, the back-addition wall, floor and eaves levels and the neighbour's window heights — the numbers the width limit, roof pitch and party-wall detailing depend on.
Chartered designers develop the infill and its glazed roof to your brief, drawn inside the permitted-development limits or to Hertsmere Borough Council's extension guidance, with the boundary and party-wall junction detailed.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until Hertsmere Borough Council issues its decision.
Sometimes not. A single-storey side-return infill can be permitted development if it is no wider than half the original house, no higher than 4 metres, and the property is not on designated land. In Aldenham West you will need a full application to Hertsmere Borough Council for anything wider or taller, for a two-storey side return, and for any side extension in a conservation area such as Aldenham and Letchmore Heath, where those rights are removed.
It is an infill that fills the narrow open alley running alongside the rear back-addition of a Victorian or Edwardian terrace — the strip of ground that is usually too small to use. Building over it squares off the ground floor, so a cramped galley kitchen becomes a full-width room. Aldenham West's period terraces are ideally suited to it, which is why the side return is one of the borough's most common extensions. Hertsmere Borough Council is the decision-maker.
Almost always. A side return is built on or up to the boundary with your neighbour, so the Party Wall etc. Act applies and you must serve notice before work starts — this is entirely separate from Hertsmere Borough Council's planning decision. We detail the party-wall junction on the drawings and flag the notice early so a surveyor can be appointed without delaying the build. This applies to your Aldenham West address specifically.
Yes, and it is common — the combined L-shape is a wraparound extension. Once the side infill joins a rear projection beyond the permitted-development depth, the whole thing needs a full householder application to Hertsmere Borough Council rather than qualifying as permitted development. We draw it as one coherent scheme so the council assesses a single footprint, which reads more clearly than two overlapping proposals. This applies to your Aldenham West address specifically.
A householder planning application in Aldenham West runs to a statutory eight-week target, and a lawful development certificate to eight weeks as well, though an incomplete pack can stall at validation. Because a side return involves the boundary and roof glazing, a complete, well-detailed submission matters — we prepare it validation-complete and manage officer queries to keep the decision on track. Hertsmere Borough Council is the decision-maker.
We price each Aldenham West side return individually, because alley width and roof form vary house to house, and send a fixed, no-obligation quote within one working day. It covers the full drawing pack with free revisions until Hertsmere Borough Council approves, and we confirm at the outset whether your infill is permitted development or needs an application. Call 020 7864 7245 to start.
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