Mansard Loft Conversion Drawings in Feltham TW13
Fixed-fee, MCIAT-chartered mansard loft conversion drawings for Feltham (TW13) homeowners — London Borough of Hounslow validation and local constraints handled from the start.
Feltham is an outer-west Hounslow suburb built largely between the wars and in the post-war decades, so the bulk of our work here is family-driven: single-storey rear extensions, side-return infills and loft conversions on 1930s semis and estate housing. Wide plots on roads such as Southern Avenue and Ashmead Road usually leave comfortable room to extend under permitted development while keeping the front elevation intact.
Where a plot sits near the St Dunstan's or Hanworth Park conservation areas, or on the lower ground close to the River Crane, we design to Hounslow Council's expectations from the outset — matching brick and roof lines, respecting the depth and height limits, and building in flood-resilient drainage detail so the application clears validation without an avoidable refusal.
Planning in Feltham (TW13): what to know before you apply
There is no published householder Article 4 direction in Feltham, so most rear and loft projects proceed under permitted development. Watch the St Dunstan's, Hanworth Park and Feltham Town Centre conservation areas, and the flood constraint on plots near the River Crane, where PD rights and extension depths are more tightly read.
Typical Feltham housing stock
Feltham is dominated by 1930s bay-fronted semis and post-war council-built estates, with generous rear gardens on roads like Southern Avenue and Glebelands Road. Plots are wide enough for single-storey rear extensions, side infills and hip-to-gable loft conversions without needing to touch the front elevation.
Streets we regularly draw for in Feltham
Southern Avenue · Glebelands Road · Ashmead Road · Browells Lane
What TW13 is actually built of
Measured from 396 classified residential buildings in TW13, not from a description of the area.
Feltham TW13 housing mix
Residential building form across the TW13 postcode district, from 396 classified buildings.
| Attached on more than one side | 41% |
|---|---|
| Attached on one side | 54% |
| Detached | 5% |
| Median building footprint | 54 m² |
| Addresses per buildingAbove about 2 means flats and maisonettes dominate | 1.56 |
| Buildings classified | 396 |
Source: Ordnance Survey National Geographic Database (derived statistics). Contains OS data © Crown copyright and database right 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. Extracted 2026-08-17.
Mansard Loft Conversion Drawings for Feltham (TW13) homes: the package and the process
A mansard is a rebuild of the roof, so the drawings carry more structure than a dormer scheme: the new front and rear slopes with their pitch angles set out, the upstand and party wall junctions, the parapet and gutter detail, and a street-scene elevation showing the new roof against its neighbours.
That street scene usually decides the application. Where a terrace already has approved mansards, the drawing shows the new roof matching their line, pitch and window rhythm; where it would be the first, the case is made on the roof form itself. Either way the argument is drawn, not written.
Mansards belong to terraces and to parapeted stock. The form works because a near-vertical rear wall can rise off the party walls and sit behind a parapet, which is why it is the usual answer in tightly controlled streets and rarely the right answer on a detached house.
What is a mansard loft conversion?
A mansard replaces the rear roof slope — or, less commonly, the front and rear slopes together — with a new near-vertical wall rising from the party walls to a shallow flat roof at the ridge, with small dormer windows set into it. Unlike a dormer, which sits within the existing roof, a mansard changes the shape of the roof itself, which is why it is usually reserved for terraces where the extra headroom and floor area are worth the more involved planning and construction process. Because the new wall runs almost the full width of the house between the party walls, a mansard typically delivers noticeably more usable floor area than a single dormer of any kind, which is why it remains the preferred option on period terraces where every square metre of loft counts.
Does a mansard loft conversion need planning permission in London?
Yes, almost always. Permitted development rights for roof alterations are volume- and shape-limited, and a mansard goes well beyond what those limits allow because it materially alters the roof's profile rather than adding to it. Every mansard we draw is prepared as a full householder planning application, with a design and access statement where the borough requires one, so the council can properly assess the change to the roofline and its impact on neighbours and the street scene.
Why do conservation areas favour mansards?
Many London conservation areas already contain mansard roofs as part of the original streetscape — grand Georgian and Victorian terraces were frequently built with a mansard attic storey behind a parapet, so a matching modern mansard often reads as a restoration of the intended roofline rather than an alteration. Getting that read right depends on matching the existing slate or tile colour, the proportion and spacing of the dormer windows, and the eaves and parapet detailing of the host terrace — details we design in from the first drawing rather than treating as an afterthought.
- Slate or tile colour and coursing matched to the existing roof and neighbouring properties
- Dormer window proportions and spacing aligned to the terrace's existing rhythm
- Eaves, parapet and party wall junctions detailed to sit flush with neighbouring roofs
| Package | Scope | Planning route | Fee from |
|---|---|---|---|
| Rear mansard, planning only | Design, planning drawings and supporting statement | Householder planning | £1,600 |
| Rear mansard, planning and building regs | Planning drawings plus structural and Part L detailing | Householder planning | £2,200 |
| Front and rear mansard | Full roof rebuild on both slopes, with structural | Householder planning | £2,400 |
Mansard Loft Conversion Drawings in Feltham TW13 — FAQs
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