Dormer, hip-to-gable and mansard loft conversion drawings for Aldenham West homes — prepared to Hertsmere Borough Council's design guidance, delivered in days and revised free until your decision lands, with a free approval-odds score 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.
Aldenham West's roofs set the brief. 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 its lofts sit under shallow-pitched roofs and integral garages typical of that period's building and hipped roofs with shallow pitches typical of 1930s building — the geometry that decides whether a rear dormer, a hip-to-gable or a mansard gives you the headroom you want. Hertsmere Borough Council assesses loft proposals against Hertsmere Borough Council's adopted local plan and its householder design guidance, and its case officers read each roof against the pair next door and the wider street before they read the plans.
That makes drawing quality decisive. We measure ridge and eaves heights, roof pitch and the existing stair, calculate the added volume against the permitted-development limits exactly, and show the workings on the drawings so Hertsmere Borough Council can verify them. 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 page rather than leave it for the case officer to raise.
Aldenham West also carries protected 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. We check your address against those designations before a line is drawn.
Many Aldenham West loft conversions proceed without planning permission — a rear dormer within the permitted-development volume limits (40 cubic metres on a terrace, 50 on a semi or detached house) is usually lawful. You will normally need a full application to Hertsmere Borough Council if any of these apply:
We draw the roof line, the ridge height and the neighbour's daylight on the page — the relationships Hertsmere Borough Council's officers check first — 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, pulled from official planning statistics and updated 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. Professionally prepared loft drawings anticipate those pressure points before submission, which is why complete, policy-literate packs are decided faster and refused less often than DIY applications.
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 recurring loft is the rear dormer — a box across the back roof slope that turns a cramped attic into a full-height double bedroom and en-suite. On shallow-pitched roofs and integral garages typical of that period's building, that is usually the most efficient use of the roof; where the stock is hipped roofs with shallow pitches typical of 1930s building, a hip-to-gable followed by a rear dormer unlocks far more space, though it needs a full application.
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 draw the dormer inside the volume allowance, keep the flat-roof build-up below the ridge, and set the face back from the eaves as the rules require — so the pack answers Hertsmere Borough Council's questions before they are asked. Where permitted-development rights are exhausted or removed, we prepare a householder application composed to the borough's roof-alteration guidance instead.
We draw loft conversions on every street in the borough. A few of the neighbourhoods where Aldenham West roofs come up most often:
Loft conversion drawings for Aldenham's conservation area designated in 1973 — measured, volume-checked and drawn to Hertsmere Borough Council's guidance.
Loft conversion drawings for Letchmore Heath's conservation area designated in 1969 — measured, volume-checked and drawn to Hertsmere Borough Council's guidance.
Loft conversion drawings for Patchetts Green and Delrow's conservation area designated in 1998 — measured, volume-checked and drawn to Hertsmere Borough Council's guidance.
Loft conversion drawings for Radlett North's conservation area designated in 1988 — measured, volume-checked and drawn to Hertsmere Borough Council's guidance.
Loft conversion drawings for Round Bush's conservation area designated in 1978 — measured, volume-checked and drawn to Hertsmere Borough Council's guidance.
Loft conversion drawings for Aldenham's civil parish within Aldenham West — measured, volume-checked and drawn to Hertsmere Borough Council's guidance.
The right loft in Aldenham West depends on your roof. This is how the main types compare on planning route and the space they add.
| Loft type | Permitted development? | Space & headroom | What Hertsmere Borough Council checks |
|---|---|---|---|
| Rear dormer | Usually yes, within volume limits | Full-height double room at the back | Volume, set-back from eaves, ridge height |
| Hip-to-gable | No — full application | Extends the whole side of the roof | Roof bulk and the symmetry of the pair |
| Mansard | No — full application | Maximum floor area across the roof | Street character, especially in conservation areas |
| Rooflights only | Usually yes (Class C) | Light and headroom, no extra footprint | Whether rooflights sit within the existing slope |
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 loft applications — most drawings are submission-ready within seven days of survey.
Tell us your Aldenham West postcode and roof type. We confirm your conservation and Article 4 status, how much permitted-development volume you have left, and score your odds against live Hertsmere Borough Council decisions.
We measure ridge and eaves heights, roof pitch, joist levels and the existing stair — the numbers the volume calculation and head heights depend on.
Chartered designers develop the dormer, hip-to-gable or mansard to your brief, drawn inside the Class B limits or to Hertsmere Borough Council's roof-alteration guidance.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until Hertsmere Borough Council issues its decision.
Often not. A rear dormer within 40 cubic metres on a terrace, or 50 on a semi-detached or detached house, set back from the eaves and no higher than the ridge, is usually permitted development. In Aldenham West the main exceptions are hip-to-gable conversions, dormers visible from the highway, and homes in conservation areas such as Aldenham and Letchmore Heath or on streets with an Article 4 direction. Hertsmere Borough Council is the decision-maker.
Generally no. In conservation areas including Aldenham and Letchmore Heath, Class B permitted-development rights for lofts are removed, so a rear dormer that would be lawful elsewhere needs a full application to Hertsmere Borough Council. 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 check your exact address before drawing.
On shallow-pitched roofs and integral garages typical of that period's building, common across Aldenham West, a rear dormer is usually the most efficient conversion and often permitted development. Where the roof is hipped roofs with shallow pitches typical of 1930s building, a hip-to-gable followed by a rear dormer gains far more usable space but needs planning permission. Our survey confirms which your roof supports before we draw. Hertsmere Borough Council is the decision-maker.
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 validation can add time if the pack is incomplete. We submit validation-complete drawings and manage case-officer queries to keep the decision on track. Hertsmere Borough Council is the decision-maker.
If your dormer is permitted development, a lawful development certificate from Hertsmere Borough Council is council-stamped proof of that — worth having, because every buyer's solicitor will ask for it when you sell. We prepare and submit the certificate application with the same drawing pack. This applies to your Aldenham West address specifically.
Every roof is different, so we quote each Aldenham West project individually — a fixed, no-obligation price back within one working day. The quote covers the full drawing pack with free revisions until Hertsmere Borough Council approves, and we tell you upfront whether your loft qualifies as permitted development. Call 020 7864 7245 to start.
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.
Same fixed quotes, same fast drawings — wherever your project is.