Every loft type on every Merton roofline: dormer, mansard, hip-to-gable, L-shape, Velux. Certificate route or full planning, plus building regulations, the structural calculations and every party wall notice, at one fixed price.
Loft conversion drawings in Merton are the full set the London Borough of Merton needs before it can determine an application: measured plans of what exists and what is proposed, elevations, sections at 1:100 and 1:50, a location plan and a site plan, together with whatever written statement the officer handling it asks to see. Since the borough grants 88.9% of householder decisions, the drawings are usually what an application turns on rather than the principle behind it.
Prepared and reviewed by the chartered technologist team at Architectural Drawings London — MCIAT chartered, £2m PI insured.Last reviewed 2026-08-03.
Every loft type across every Merton roof line — dormer, mansard, hip-to-gable, L-shape, Velux. LDC or full planning route, building regulations, structural calculations and party wall notices, all fixed price.
Housing stock in Merton: Victorian villas in Wimbledon; Edwardian terraces in Tooting and Colliers Wood; 1930s semi-detached in Morden and Raynes Park; post-war flats in Mitcham.
Character: Wimbledon is heavily conservation-controlled; outer Merton (Morden, Mitcham) is permissive.
Before any quote goes out we settle the two things that decide feasibility: whether the Merton loft has the head height, and whether the existing structure can take what is being asked of it.
Most Merton lofts will qualify for a Lawful Development Certificate. What we test before anything else is Article 4 and any conservation constraint on the address.
Option studies including massing, internal layout and roof geometry.
Staircase geometry under Part K, escape under Part B, insulation under Part L, and acoustic separation under Part E wherever the loft adjoins another dwelling.
Ridge beam, purlins, the steelwork, upgraded floor joists and dormer framing — each of them carrying a chartered engineer's signature for Building Control.
Nearly every loft here means notifying a neighbour. A beam cut into the party wall counts as section 2 work, and the section 3 notice for it has to be served two months ahead. We draft the notices and deal with the appointed surveyors.
Single planning or regs submission.
Planning + building regs + structural.
Listed, conservation, complex sites.
Move the controls for an indicative figure. It anchors your budget — it is not a quote. Every project is priced after a free survey.
Build costs are separate and quoted by your contractor. See our published fees.
Each Merton district we draw in, the stock that fills it, and the authority validating a loft conversion raised there. Charges in this table are 2026 statutory England rates, and none of them is our design fee.
| Postcode | Area | Dominant stock | What it means for a loft conversion |
|---|---|---|---|
| SW19 | Wimbledon / Colliers Wood | Victorian villas, Edwardian terraces | SW19 straddles the Merton and Wandsworth line through Wimbledon and Colliers Wood, so establish which council validates before any loft drawings are submitted. |
| SW20 | Raynes Park | Victorian villas, Edwardian terraces | Raynes Park has SW20 to itself. Merton validates the loft, and the SW20 designation map applies to any change that shows externally. |
| SM4 | Morden | 1930s semi-detached, post-war flats | A loft conversion at an SM4 address in Morden is determined by Merton Council under its own Local Plan policies for Morden. |
| CR4 | Mitcham | 1930s semi-detached, post-war estates | Mitcham sits in CR4, where Merton determines a loft conversion under its own Local Plan policies for that end of the borough. |
| SW16 | Streatham / Norbury | Edwardian terraces, post-war flats | Four authorities share SW16. A Streatham or Norbury loft may be Lambeth's, Wandsworth's, Merton's or Croydon's, and the policies map settles which one street by street. |
| SW17 | Tooting / Earlsfield | Edwardian terraces | Tooting and Earlsfield share SW17 across the Wandsworth boundary, so a loft there may be determined by either council depending on the address. |
Pitch, wall construction and plot depth are one thing in Wimbledon and quite another in Mitcham, and every difference surfaces in what a loft can be made to do at that address.
Merton conservation designations: twenty-eight of them, Mitcham Cricket Green, Wimbledon Common and Wimbledon Village among the names. Designation removes the permitted-development route, so a loft goes in at £548 as a householder application over 8 weeks, where the prior approval route would have cost £249 and taken 6. Of the twenty-eight, John Innes is the one that sends a Merton loft back for redesign most often.
Article 4 and your Merton loft: the borough has made no direction of that kind, so permitted development for a loft generally survives outside Merton's conservation areas and listed curtilages. An owner in SW19 records that lawfulness with a Lawful Development Certificate, which costs £274.
What Merton is built from: Victorian villas in Wimbledon, Edwardian terraces through Tooting and Colliers Wood, 1930s semis at Morden and Raynes Park, post-war flats in Mitcham. The 1930s band alone accounts for 24.6% of 87,810 dwellings, with a further 27.1% built between 1900 and 1929 (VOA CTSOP4.1, at 31 March 2025). Wimbledon is heavily conservation-controlled and outer Merton is not. That mix decides the loft route here more than any postcode does, and the householder application behind it is £548 direct to the council, with 8 weeks running to a decision from validation.
Sources for this Merton loft conversion page: borough policies maps and conservation-area registers (2025–26), Royal Mail postcode district boundaries, the Town and Country Planning (Fees for Applications) (England) Regulations, the Town and Country Planning (General Permitted Development) (England) Order 2015 as amended, and the Party Wall etc. Act 1996.
What Merton owners ask us before committing to a loft, answered against this borough's own record of decisions.
Start a free quote →Under the standard householder allowances a Merton loft has 40 cubic metres to work with on a terrace, or 50 on a semi-detached house, with matching materials and a 20cm setback from the eaves. Flats, conservation areas and listed buildings sit outside that and need full planning. We confirm eligibility on the free site visit; nobody should be assuming it from a postcode.
Two figures decide a Merton loft budget. Ours takes in the route through planning, the building regulations set and the structural calculations, at a single quoted price. The builder's covers construction, and that swings with loft type — putting up a standard dormer costs materially less than putting up a mansard. Our half is fixed before work begins; see our fees.
Mansards were never common Merton stock, so the council takes each one on its merits. Put one at the rear of a suitable terrace or a semi, cut to answer the roofscape already there, and it has a fair chance with the right drawings and a heritage note where the setting warrants one. The broader record supports that reading: 88.9% of householder decisions in this borough were grants.
2.3m from ceiling joists to the underside of the ridge is the working minimum for a standard conversion in Merton. Below 2.2m you are usually into dropping the ceiling of the room beneath, which costs height down there, or redesigning the whole thing as a mansard.
Party wall obligations follow almost every loft in this borough — the Party Wall Act sets out which section covers what. On the denser terraced streets, and around Wimbledon Village in particular, the neighbour behind you may also raise right-to-light over a rear dormer. Both conversations are ours to have.
Wimbledon's Victorian villas take rear dormers most readily. The semi-detached stock at Morden and Raynes Park suits hip-to-gable. A mansard gets seriously considered on period terraces and in conservation settings, and a Velux-only conversion works wherever ridge height already allows it. The structural and planning route is settled at survey.
We cover all Merton postcodes — SW16, SW17, SW19, SW20, CR4 — with surveyors based locally. Survey appointments within 3 working days. Our structural engineer is London-based and attends site when required.
Notices go to every adjoining owner, generally because a steel has to bear into the shared wall, or because that wall is going up in height. Two months' notice is required for work of that kind. From there the neighbour has fourteen days in which to consent or to dissent. We coordinate the process, and our own engineer covers the structural half of it.
If your property sits on a boundary, here are the neighbouring options.
Merton grants 2,216 of its 2,494 householder decisions, 88.9% against 83.0% pooled across London, so refusals here concentrate somewhere specific: 246 of the 735 larger householder prior approvals it determined were turned down, 33.5%, where the capital runs at 24.9% (MHCLG planning statistics, retrieved 1 September 2026). Those are the schemes that end up in front of an inspector. One chartered team handles the whole route.
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