Dormer, hip-to-gable and mansard loft conversion drawings for Probus & St Erme homes — prepared to Cornwall Council's design guidance, delivered in days and revised free until your decision lands, with a free approval-odds score first.
Cornwall Council granted 97% of the householder planning decisions it made in its latest published year — 10 points above the 87% England-wide householder average. Probus & St Erme contains the PROBUS conservation area (PROBUS designated 1991), so materials, fenestration and roof form are assessed against the appraisal, which is where a policy-literate drawing pack earns its keep. Its dominant Victorian (1837–1901) housing stock sets the design brief on most streets.
The permitted-development ceilings are fixed: 40m³ of new roof volume for a terraced loft and 50m³ for a semi or detached house under Class B, plus a 3m single-storey rear extension on a terrace or 4m on a detached house under Class A. In conservation areas such as PROBUS those rights are removed, so we confirm your exact address before a line is drawn. A validated householder application in Probus & St Erme is determined against an 8-week statutory target.
PROBUS (conservation area designated in 1991), St. Erme (civil parish within Probus & St Erme), Ladock (civil parish within Probus & St Erme), Probus (civil parish within Probus & St Erme) and St. Clement (civil parish within Probus & St Erme) — these are the Probus & St Erme pockets our drawings cover most. Heritage designations here include PROBUS. Cornwall Council weighs each proposal against Cornwall Council's development plan and the design policies it applies to householder applications, where the 3,510 homes here are 26% pre-1900, 19% 1983-1992, 11% 1973-1982, which is what sets the realistic roof and rear-projection options. On roofs the borough is steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building and trussed-rafter roofs typical of 1980s building, over Victorian and earlier houses (26% of 3,510 homes), 1980s estate houses (19%) and 1970s and early-1980s houses (11%).
Before anything is drawn we check your address against the designations that apply in Probus & St Erme: PROBUS (conservation area designated in 1991). Inside those boundaries permitted development is curtailed and Cornwall 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, Probus & St Erme takes in St. Erme, Ladock, Probus and St. Clement. No Article 4 direction is recorded for Cornwall Council, but Probus & St Erme's 1 conservation area still limit permitted development on those streets.
On stock, Probus & St Erme is Victorian and earlier houses (26% of 3,510 homes), 1980s estate houses (19%) and 1970s and early-1980s houses (11%) — which is why steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building and trussed-rafter roofs typical of 1980s building govern what a loft or rear projection can realistically be. Cornwall Council decided 1,863 householder applications in the latest published year and granted 97%, with 76% issued inside the eight-week target. That decision record, not a national figure, is what we design to.
The full build-period split for Probus & St Erme runs pre-1900 26% (930 homes), 1900-1918 1% (50 homes), 1919-1929 1% (30 homes), 1930-1939 2% (80 homes), 1945-1954 3% (110 homes), 1955-1964 4% (130 homes), 1965-1972 8% (270 homes), 1973-1982 11% (370 homes), 1983-1992 19% (650 homes), 1993-1999 4% (140 homes) and 2000-2008 7% (240 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.
Cornwall Council also decides for Bodmin St Petroc's, Bude, Camborne Trelowarren, Camelford & Boscastle, Falmouth Arwenack, Feock & Kea, Hayle West and Land's End, so a decision in Probus & St Erme 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 Probus & St Erme and Cornwall Council. These are the numbers that decide what is realistic on your street, so we work from them rather than from national averages.
| Measure | Probus & St Erme |
|---|---|
| Dwellings recorded | 3,510 |
| Built pre-1900 | 930 (26%) |
| Built 1900-1918 | 50 (1%) |
| Built 1919-1929 | 30 (1%) |
| Built 1930-1939 | 80 (2%) |
| Built 1945-1954 | 110 (3%) |
| Built 1955-1964 | 130 (4%) |
| Built 1965-1972 | 270 (8%) |
| Built 1973-1982 | 370 (11%) |
| Built 1983-1992 | 650 (19%) |
| Built 1993-1999 | 140 (4%) |
| Built 2000-2008 | 240 (7%) |
| Built before 1919 | 28% |
| Built 1919–1939 | 3% |
| Built 1945–2008 | 54% |
| Conservation areas in Probus & St Erme | 1 (PROBUS) |
| Conservation areas district-wide | 145 |
| Article 4 directions recorded | 0 |
| Householder applications decided | 1,863 |
| Householder applications granted | 97% |
| Decided within 8 weeks | 76% |
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 Cornwall Council's own, from MHCLG live table PS2 for the year to 31 March 2026.
Probus & St Erme's roofs set the brief. The borough is built largely from Victorian and earlier houses (26% of 3,510 homes), 1980s estate houses (19%) and 1970s and early-1980s houses (11%), and its lofts sit under steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 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. Cornwall Council assesses loft proposals against Cornwall Council's development plan and the design policies it applies to householder applications, 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 Cornwall Council can verify them. Probus & St Erme contains the PROBUS conservation area (PROBUS designated 1991), 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.
Probus & St Erme also carries protected streets — PROBUS among them. No Article 4 direction is recorded for Cornwall Council, but Probus & St Erme's 1 conservation area still limit permitted development on those streets. We check your address against those designations before a line is drawn.
Many Probus & St Erme 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 Cornwall Council if any of these apply:
We draw the roof line, the ridge height and the neighbour's daylight on the page — the relationships Cornwall 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 Cornwall Council's real householder decision record, pulled from official planning statistics and updated as new data lands. Cornwall Council granted 97% of its householder applications in the year to 31 March 2026, and PROBUS 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 PROBUS, St. Erme and Ladock, 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 steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 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 3,510 homes here are 26% pre-1900, 19% 1983-1992, 11% 1973-1982, 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 Cornwall 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 Probus & St Erme roofs come up most often:
Loft conversion drawings for PROBUS's conservation area designated in 1991 — measured, volume-checked and drawn to Cornwall Council's guidance.
Loft conversion drawings for St. Erme's civil parish within Probus & St Erme — measured, volume-checked and drawn to Cornwall Council's guidance.
Loft conversion drawings for Ladock's civil parish within Probus & St Erme — measured, volume-checked and drawn to Cornwall Council's guidance.
Loft conversion drawings for Probus's civil parish within Probus & St Erme — measured, volume-checked and drawn to Cornwall Council's guidance.
Loft conversion drawings for St. Clement's civil parish within Probus & St Erme — measured, volume-checked and drawn to Cornwall Council's guidance.
The right loft in Probus & St Erme 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 Cornwall 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 PROBUS and Article 4 directions can remove permitted-development rights.
A fixed process built around how Cornwall Council validates and decides householder loft applications — most drawings are submission-ready within seven days of survey.
Tell us your Probus & St Erme 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 Cornwall 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 Cornwall Council's roof-alteration guidance.
We submit the certificate or application, manage validation and case-officer queries, and revise the drawings free until Cornwall 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 Probus & St Erme the main exceptions are hip-to-gable conversions, dormers visible from the highway, and homes in conservation areas such as PROBUS or on streets with an Article 4 direction. Cornwall Council is the decision-maker.
Generally no. In conservation areas including PROBUS, Class B permitted-development rights for lofts are removed, so a rear dormer that would be lawful elsewhere needs a full application to Cornwall Council. No Article 4 direction is recorded for Cornwall Council, but Probus & St Erme's 1 conservation area still limit permitted development on those streets. We check your exact address before drawing.
On steeply pitched slate roofs, valley gutters and party parapets typical of pre-1900 building, common across Probus & St Erme, 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. Cornwall Council is the decision-maker.
A householder planning application in Probus & St Erme 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. Cornwall Council is the decision-maker.
If your dormer is permitted development, a lawful development certificate from Cornwall 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 Probus & St Erme address specifically.
Every roof is different, so we quote each Probus & St Erme project individually — a fixed, no-obligation price back within one working day. The quote covers the full drawing pack with free revisions until Cornwall 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.