Floor plans for loft extension planning in Chislehurst
Loft extension planning in Chislehurst starts with an accurate floor plan of the house as it stands. DrawingsDirect measures the property and draws the existing floor plans from £275, and those plans then carry the loft design, the planning or lawful development application to Bromley council and, later, the Building Regulations drawings.
Fixed fee from £275 · all prices
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Why the loft design starts on the floor below
A loft conversion is drawn from the house downwards. The new stair has to land somewhere on the first floor, headroom has to clear the existing landing, and the dormer or gable wall sits on walls that must line up with the rooms beneath. None of that can be designed without measured plans of every storey, including the loft void as it is today.
Chislehurst is in the London Borough of Bromley, so Bromley council is the planning authority for any loft application in Chislehurst. Whichever route the project takes, the council expects to see the house as existing and as proposed, drawn to scale. Our floor plans service produces the existing set, and the proposed drawings are built on top of it rather than redrawn from scratch.
What the £275 survey and floor plans cover
The fixed fee for a measured survey with floor plans starts at £275, as shown on our price list. The survey measures the rooms, walls, openings and stair, and the drawings are prepared to the MCIAT standard our chartered architectural technologists work to.
The result is a scaled set of existing floor plans you own and can pass to any designer, builder or engineer. More detail on the visit itself is on the measured building survey page.
The national register held on the MHCLG Planning Data Platform lists 47 conservation-area entries for Bromley that carry a designation date, and those dates run from 1971 to 2022.
Gable loft conversions in Chislehurst: what changes on the drawings
A gable loft conversion replaces a sloping hipped end of the roof with a vertical wall, which is why it changes far more of the drawing set than a few rooflights would. The floor plans show the new room and stair, but the roof plan and the side elevation change too, and those are the drawings a planning officer reads first on a semi-detached or detached Chislehurst house.
Many gable conversions are paired with a rear dormer. Both are covered on our hip-to-gable loft conversion drawings and loft conversion drawings pages; the existing floor plans are the same starting point for either.
Permitted development, a certificate, or full planning in Bromley
Many house lofts can be built under permitted development, without a planning application, and the usual way to prove that is a lawful development certificate. Bromley council decided 1,030 of these certificates across the latest eight published quarters, according to our analysis of MHCLG planning application statistics. The lawful development certificate drawings page explains what that application needs.
The same statistics show the borough determined 39 larger home extension prior approvals in that period and granted 10 of them. That route applies to single-storey rear extensions rather than lofts, but it matters if the loft is part of a wider plan for the house. Where permitted development does not apply, the floor plans go into a householder planning application instead; see our planning drawings page.
Check for a conservation area before planning the roof
Roof extensions under permitted development are not available on houses in a conservation area, so it is worth knowing early whether your house is in one. The national register held on the MHCLG Planning Data Platform lists 47 conservation-area entries for Bromley that carry a designation date, and those dates run from 1971 to 2022.
That register can be incomplete, and the same caution applies to Article 4 directions, which can remove permitted development rights street by street. Before deciding between a certificate and a planning application, look up the address on Bromley council's own conservation area map at bromley.gov.uk.
Bromley's appeal record, as context
If a loft application is refused, the owner can appeal to the Planning Inspectorate. The Planning Inspectorate Casework Database records 1,145 planning appeals decided as allowed or dismissed for Bromley in recent years, with 34% allowed, in our analysis of that database.
That figure is a record of past decisions across every kind of application in the borough. It says nothing about how a particular Chislehurst loft would fare, and a clear, accurate drawing set at the first application is still the better use of time and fees.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| £275 | DrawingsDirect starting fixed fee for floor plans measured on site | drawingsdirect.co.uk |
| 39 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 10 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 1,030 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 1,145 | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
| 34% | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
| 47 | Our analysis of MHCLG Planning Data Platform conservation-area and article-4-direction datasets (bulk snapshot retrieved 19 Oct 2026) | www.planning.data.gov.uk |
| 1971 | Our analysis of MHCLG Planning Data Platform conservation-area and article-4-direction datasets (bulk snapshot retrieved 19 Oct 2026) | www.planning.data.gov.uk |
| 2022 | Our analysis of MHCLG Planning Data Platform conservation-area and article-4-direction datasets (bulk snapshot retrieved 19 Oct 2026) | www.planning.data.gov.uk |