Loft conversion in Merton Park
A loft conversion in Merton Park can proceed under permitted development, provided a terraced house adds no more than 40 cubic metres of roof space and nothing restricts your street. When you need permission instead, Merton granted 93% of its householder decisions in the latest data. DrawingsDirect draws loft conversions from £695.
Fixed fee from £495 drawings + £200 survey (£695 total) · all prices
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Start with the allowance
Class B of the General Permitted Development Order gives a terraced house a 40 cubic metre allowance for new roof space, as set out on legislation.gov.uk. Semi-detached and detached houses have a larger allowance.
Measure the existing roof properly before deciding. We survey the loft, calculate the volume of the proposed dormer and report the figure before the design goes any further.
Merton's pace is slower than its approval rate suggests
Our analysis of the MHCLG planning application statistics shows that Merton Council made 759 householder decisions in the latest four quarters and granted 93% of them. The speed figure is less comfortable: only 75% of its non-prior-approval householder decisions were made within eight weeks.
In practice, a Merton Park loft application should be planned with a margin. A quarter of those decisions took longer than eight weeks, and builders and finance will need to wait for them.
Our analysis of the Planning Inspectorate casework database shows that 36% of Merton householder appeals were allowed.
Certificates as an alternative
Our analysis of the same statistics shows that Merton decided 270 certificates of lawful development in the latest eight quarters. A certificate is not compulsory, but it gives you and any future buyer written confirmation that the loft is lawful.
If your house is in a conservation area, or an Article 4 direction removes the Class B rights, the loft is not permitted development, so a certificate cannot be granted and a full application is required. Check your street for conservation area or Article 4 controls before you pay for design drawings.
Appeals and our fee
Our analysis of the Planning Inspectorate casework database shows that 36% of Merton householder appeals were allowed. Most were not, so the better aim is a first application that does not need one.
Our loft conversion drawings start at £695. For a dormer in particular, see our dormer loft conversion drawings, and for the measurement stage the Merton floor plans page.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| 40 cubic metres | GPDO 2015 Sch 2 Pt 1 Class B para B.1(d): roof space addition limit, terrace house (source wording: 40 cubic metres) | www.legislation.gov.uk |
| £695 | DrawingsDirect starting fixed fee for a rear extension, dormer or loft | drawingsdirect.co.uk |
| 759 | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 93% | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 75% | Our analysis of MHCLG planning application statistics, table PS2 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 270 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 36% | Our analysis of Planning Inspectorate Casework Database (released 1 Oct 2026 (Casework Database 2609)) | www.gov.uk |
Questions people ask
How long does Merton take to decide a householder application?
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Can I convert my loft without planning permission?
Photographs: David Anstiss (CC BY-SA 2.0); GRALISTAIR (CC BY-SA 4.0).
