Loft Conversion Case Study: 136 Sutton Lane, Hounslow

Loft Conversion London Borough of Hounslow ✓ Planning Permission Approved
Existing front elevation of 136 Sutton Lane, Hounslow, ahead of the approved loft conversion
Property Type
Semi-detached house
Planning Route
Full Householder Planning Permission
Local Authority
London Borough of Hounslow
Outcome
Planning Permission Approved

The Brief

The clients wanted to make significantly more use of the loft space in their semi-detached house on Sutton Lane, Hounslow, adding further bedrooms and a study without disturbing the existing ground and first-floor layout below.

Planning Route

Given the scale of the proposed rear roof extension and the addition of Juliet balconies and new front roof windows, this project required full householder planning permission rather than permitted development. We prepared the drawings and submitted the application (ref. P/2025/1381) to the London Borough of Hounslow on 1 May 2025.

The Design

The approved scheme is a rear roof extension that reworks the loft into a second bedroom with dressing area, a third bedroom, an en-suite, a study and a family bathroom, alongside a landing area off the existing staircase. To the rear, full-height glazed doors open onto two Juliet balconies, bringing natural light deep into the new bedrooms. To the front, three individual roof windows were added within the existing roof slope, keeping the alteration in proportion with the rest of the roof. Floor plans and elevations were prepared in Revit as drawings A101, A104–A107, a selection of which is shown below.

Outcome

On 9 July 2025 — around ten weeks after submission — the London Borough of Hounslow approved the application subject to standard conditions: the development must begin within three years, external materials must match the existing house, no additional windows or openings may be formed in the side elevations to protect neighbours' privacy, and the extension may only be used as part of the house rather than as a separate dwelling or for business purposes.

Following approval, SY Design Studio has prepared the Building Regulations drawing package for the project, covering structure, insulation, fire safety and the staircase, ready for the next stage of the project.

Drawing Pack

Proposed block plan showing the site boundary at 136 Sutton Lane, Hounslow
Proposed block plan, 1:500.
Proposed loft floor plan showing two new bedrooms, en-suite, study and bathroom at 136 Sutton Lane, Hounslow
Proposed loft plan, 1:50.
Proposed front, rear and side elevations for the loft conversion at 136 Sutton Lane, Hounslow, showing the Juliet balconies and front roof windows
Proposed front, rear and side elevations, 1:100.

Existing Conditions

Existing rear elevation of 136 Sutton Lane, Hounslow, prior to the approved loft conversion
Rear of the property prior to the approved extension.

Related

Loft Conversion Services → Architectural Design in Hounslow → Planning Permission Guide →