Dormer, hip-to-gable and mansard loft conversion drawings for Denne homes — prepared to Horsham District Council's design guidance, delivered in days and revised free until your decision lands, with a free approval-odds score first.
Horsham District Council granted 97% of the householder planning decisions it made in its latest published year — 10 points above the 87% England-wide householder average. Denne contains Horsham (London Road) Conservation Area, Horsham (Park Terrace Gardens) Conservation Area, Horsham Conservation Area conservation areas (Horsham (London Road) Conservation Area designated 1984), 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.
Under Class B, a rear dormer stays permitted development up to 40m³ of added roof volume on a terrace or 50m³ on a semi-detached or detached house, while Class A allows a single-storey rear extension of 3m beyond the original rear wall on a terrace and 4m on a detached house before a full application is needed. Denne carries at least one Article 4 direction, and conservation areas including Horsham (London Road) Conservation Area, Horsham (Park Terrace Gardens) Conservation Area and Horsham Conservation Area remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Denne is determined against an 8-week statutory target.
Horsham (London Road) (conservation area designated in 1984), Horsham (Park Terrace Gardens) (conservation area designated in 2023) and Horsham (conservation area designated in 1974) — these are the Denne pockets our drawings cover most. Heritage designations here include Horsham (London Road) Conservation Area, Horsham (Park Terrace Gardens) Conservation Area and Horsham Conservation Area. Horsham District Council weighs each proposal against Horsham District Council's adopted local plan and its householder design guidance, where the 4,910 homes here are 16% 1955-1964, 12% 1983-1992, 11% 2000-2008, 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 trussed-rafter roofs typical of 1980s building, over late-1950s and early-1960s houses (16% of 4,910 homes), 1980s estate houses (12%) and 2000s houses and apartments (11%).
Denne's designated heritage is specific, and it is the first thing we check against your address: Horsham (London Road) (conservation area designated in 1984), Horsham (Park Terrace Gardens) (conservation area designated in 2023) and Horsham (conservation area designated in 1974). Inside those boundaries permitted development is curtailed and Horsham District 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.
Horsham District Council has 53 recorded Article 4 directions, removing permitted development for rear and side extensions and roof enlargements such as dormers — check the address before assuming PD applies in Denne.
On stock, Denne is late-1950s and early-1960s houses (16% of 4,910 homes), 1980s estate houses (12%) and 2000s houses and apartments (11%) — which is why shallow gabled roofs typical of that period's building and trussed-rafter roofs typical of 1980s building govern what a loft or rear projection can realistically be. Horsham District Council decided 679 householder applications in the latest published year and granted 97%, with 72% issued inside the eight-week target. Those are the numbers our drawings are prepared against.
The full build-period split for Denne runs pre-1900 6% (290 homes), 1900-1918 1% (30 homes), 1919-1929 1% (30 homes), 1930-1939 5% (240 homes), 1945-1954 4% (190 homes), 1955-1964 16% (770 homes), 1965-1972 4% (190 homes), 1973-1982 10% (500 homes), 1983-1992 12% (610 homes), 1993-1999 4% (220 homes) and 2000-2008 11% (520 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.
Horsham District Council also decides for Billingshurst, Colgate & Rusper, Holbrook West and Steyning & Ashurst, so a decision in Denne 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.
The Article 4 directions recorded for this council include ART4002 - LAND AT WOLVENS FARM BILLINGSHURST ROAD ASHINGTON, ART4003 - LAND AT CODMORE HILL PULBOROUGH, ART4020/1 and ART4040. Each removes a specific permitted-development right inside its own boundary, which is why the check is done on the address rather than on the town.
Published figures for Denne and Horsham District Council. These are the numbers that decide what is realistic on your street, so we work from them rather than from national averages.
| Measure | Denne |
|---|---|
| Dwellings recorded | 4,910 |
| Built pre-1900 | 290 (6%) |
| Built 1900-1918 | 30 (1%) |
| Built 1919-1929 | 30 (1%) |
| Built 1930-1939 | 240 (5%) |
| Built 1945-1954 | 190 (4%) |
| Built 1955-1964 | 770 (16%) |
| Built 1965-1972 | 190 (4%) |
| Built 1973-1982 | 500 (10%) |
| Built 1983-1992 | 610 (12%) |
| Built 1993-1999 | 220 (4%) |
| Built 2000-2008 | 520 (11%) |
| Built before 1919 | 7% |
| Built 1919–1939 | 5% |
| Built 1945–2008 | 61% |
| Conservation areas in Denne | 3 (Horsham (London Road) Conservation Area, Horsham (Park Terrace Gardens) Conservation Area…) |
| Conservation areas district-wide | 40 |
| Article 4 directions recorded | 53 |
| Householder applications decided | 679 |
| Householder applications granted | 97% |
| Decided within 8 weeks | 72% |
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 Horsham District Council's own, from MHCLG live table PS2 for the year to 31 March 2026.
Denne's roofs set the brief. The borough is built largely from late-1950s and early-1960s houses (16% of 4,910 homes), 1980s estate houses (12%) and 2000s houses and apartments (11%), and its lofts sit under shallow gabled roofs typical of that period's building and trussed-rafter roofs typical of 1980s building — the geometry that decides whether a rear dormer, a hip-to-gable or a mansard gives you the headroom you want. Horsham District Council assesses loft proposals against Horsham District 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 Horsham District Council can verify them. Denne contains Horsham (London Road) Conservation Area, Horsham (Park Terrace Gardens) Conservation Area, Horsham Conservation Area conservation areas (Horsham (London Road) Conservation Area designated 1984), 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.
Denne also carries protected streets — Horsham (London Road) Conservation Area, Horsham (Park Terrace Gardens) Conservation Area and Horsham Conservation Area among them. Horsham District Council has 53 recorded Article 4 directions, removing permitted development for rear and side extensions and roof enlargements such as dormers — check the address before assuming PD applies in Denne. We check your address against those designations before a line is drawn.
Many Denne 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 Horsham District Council if any of these apply:
We draw the roof line, the ridge height and the neighbour's daylight on the page — the relationships Horsham District 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 Horsham District Council's real householder decision record, pulled from official planning statistics and updated as new data lands. Horsham District Council granted 97% of its householder applications in the year to 31 March 2026, and Horsham (London Road) Conservation Area 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 Horsham (London Road), Horsham (Park Terrace Gardens) and Horsham, 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 gabled roofs typical of that period's building, that is usually the most efficient use of the roof; where the stock is trussed-rafter roofs typical of 1980s building, a hip-to-gable followed by a rear dormer unlocks far more space, though it needs a full application.
The 4,910 homes here are 16% 1955-1964, 12% 1983-1992, 11% 2000-2008, 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 Horsham District 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 Denne roofs come up most often:
Loft conversion drawings for Horsham (London Road)'s conservation area designated in 1984 — measured, volume-checked and drawn to Horsham District Council's guidance.
Loft conversion drawings for Horsham (Park Terrace Gardens)'s conservation area designated in 2023 — measured, volume-checked and drawn to Horsham District Council's guidance.
Loft conversion drawings for Horsham's conservation area designated in 1974 — measured, volume-checked and drawn to Horsham District Council's guidance.
The right loft in Denne 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 Horsham District 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 Horsham (London Road) Conservation Area and Horsham (Park Terrace Gardens) Conservation Area and Article 4 directions can remove permitted-development rights.
A fixed process built around how Horsham District Council validates and decides householder loft applications — most drawings are submission-ready within seven days of survey.
Tell us your Denne 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 Horsham District 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 Horsham District Council's roof-alteration guidance.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until Horsham District 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 Denne the main exceptions are hip-to-gable conversions, dormers visible from the highway, and homes in conservation areas such as Horsham (London Road) Conservation Area and Horsham (Park Terrace Gardens) Conservation Area or on streets with an Article 4 direction. Horsham District Council is the decision-maker.
Generally no. In conservation areas including Horsham (London Road) Conservation Area and Horsham (Park Terrace Gardens) Conservation Area, Class B permitted-development rights for lofts are removed, so a rear dormer that would be lawful elsewhere needs a full application to Horsham District Council. Horsham District Council has 53 recorded Article 4 directions, removing permitted development for rear and side extensions and roof enlargements such as dormers — check the address before assuming PD applies in Denne. We check your exact address before drawing.
On shallow gabled roofs typical of that period's building, common across Denne, a rear dormer is usually the most efficient conversion and often permitted development. Where the roof is trussed-rafter roofs typical of 1980s 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. Horsham District Council is the decision-maker.
A householder planning application in Denne 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. Horsham District Council is the decision-maker.
If your dormer is permitted development, a lawful development certificate from Horsham District 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 Denne address specifically.
Every roof is different, so we quote each Denne project individually — a fixed, no-obligation price back within one working day. The quote covers the full drawing pack with free revisions until Horsham District Council approves, and we tell you upfront whether your loft qualifies as permitted development. Call 020 7864 7245 to start.
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