Begin with the roof you have
Kennington's conservation statement treats historic roofscape and chimneys as important and says roof extensions are inappropriate in many cases. The existing roof form is therefore a starting constraint, not empty space waiting to be replaced.
The survey records the shape and construction that can be inspected, together with the available height and the position of existing openings. We separate measured facts from concealed conditions requiring investigation. Photographs of a similar-looking house do not establish the structure or scope available in yours. Before drawing a new room, the design needs to understand which parts of the existing roof would remain, which would change and how those changes could be carried out.
Test the stair before allocating the bedroom
A new upper room must have a workable connection to the house. We examine where a stair could arrive and how it would affect the landing or room beneath. The layout is tested in section, with the actual floor and roof levels included. This avoids a common design trap: fitting an attractive room into the roof plan while leaving no convincing route to reach it. The lost space below belongs in the assessment of the gain above.
We also consider what the room is intended to hold. Draw the bed, desk or storage at realistic sizes and identify where headroom permits comfortable movement. The lower parts of a sloping room may be useful for furniture, but they should not be counted as if all the floor can be used in the same way. Compare alternatives by the quality of the usable space, not simply by the outline of a new floor on a drawing.
Match the design ambition to the heritage context
Lambeth's adopted Design Guide favours retaining historic roof forms on heritage buildings and within conservation areas, where modest dormers or small rooflights may be preferable to extensive roof additions. That is guidance for assessing options, not a promise that any particular opening will be accepted.
We compare a retained-roof option with any proposed enlargement and make the differences explicit. The comparison includes visible form, existing details, internal space and the effect on the building as a whole. Where a larger intervention is not supportable, the brief may need to change. Better storage, a different use for an existing room or a more limited loft arrangement can be considered without presenting an unsuitable roof alteration as an inevitable part of the project.
Sources: Lambeth Design Guide Part 4: alterations, extensions and retrofit
Coordinate the new floor with the existing house
Structural information is developed for the actual arrangement. The design identifies where new loads and connections would be introduced and what access is needed to construct them. That investigation may affect rooms outside the loft, so the proposed scope shows the relevant areas of opening up and making good. It is more useful to understand those effects early than to describe the work as confined to the roof and discover otherwise during installation.
The room's intended use also brings questions about services, thermal performance, ventilation and the route through the house. We arrange the relevant design input and coordinate it with the layout. Equipment and access zones are shown before storage is fitted around them. If a bathroom is being considered upstairs, its connection requirements are assessed independently of whether the room fits on plan. Each additional function has to work as a complete installation.
Choose the correct approval route
Lambeth's householder application guidance covers loft proposals to a single house. Southwark's checklist likewise includes loft conversions but directs applications concerning flats to the full planning route. The building type and its authority must be established before choosing the application.
We keep evidence of the proposed dimensions, existing building and planning position together. If work is considered capable of proceeding without a planning application, the basis for that conclusion still needs to be established for this property. Other applicable consents and technical approvals remain separate questions. A neighbouring roof addition, an old drawing or an informal comment is not substituted for the checks needed by the proposed scheme.
Sources: Lambeth householder planning applications · Southwark householder planning checklist
Plan how the house is protected during construction
Roof work requires a practical sequence for protecting the existing building and moving materials to the work area. We discuss access, temporary arrangements and the effect on occupation before construction is agreed. The route through the property and the rooms beneath are part of that plan. Retained surfaces and possessions are identified for protection, and the scope explains where final making good is included after structural and service work is complete.
When the work is ready for review, inspect the new space together with the route leading to it. Test doors, lighting controls, storage access and the operation of any installed equipment. Review the junctions where new and existing finishes meet. Keep the relevant design and completion information with the property record, including the agreed use and any outstanding item. The successful outcome is an integrated room that can be reached and maintained comfortably.
Before work begins
Loft conversions in Kennington: questions
Is a mansard an appropriate starting assumption in the Kennington conservation area?
No. The conservation statement warns that roof additions are unsuitable in many locations and identifies the importance of existing roof forms. We start with the particular building and terrace, then compare any supported option with using the existing roof more modestly. A familiar roof style elsewhere is not an entitlement here.
Can a top-floor flat use the same application route as a whole house?
That should not be assumed. Southwark distinguishes applications for flat alterations from its householder route. A flat project also needs its ownership and roof-space rights checked. The proposal should establish both the relevant authority and what the owner can authorise before drawings are developed around an enlarged roof.
What if the only stair position takes space from another bedroom?
That trade-off needs to be shown clearly in the options. We draw the affected room and the new stair together, including furniture and circulation. The added loft accommodation is then assessed against what is lost or compromised below. Sometimes a different use of existing rooms provides a more satisfactory result.
Can eaves storage make low space useful?
It may, provided the dimensions and access suit the items to be stored and the construction allows the proposed arrangement. We consider door openings, internal divisions and any service access that must remain. Storage is designed after the roof and room build-up are understood, so it does not rely on unfinished survey dimensions.
What should I send before a loft feasibility discussion?
Share existing plans if you have them, photographs of the roof space where safely available and a description of the room you want. Include known listing or conservation information and previous proposals. Tell us whether the property is one house or a flat; that distinction affects the investigation from the outset.
Official sources
Kennington conservation area statement · Lambeth Design Guide Part 4: alterations, extensions and retrofit · Lambeth householder planning applications · Southwark householder planning checklist
Checked 4 November 2026. Maps, list entries and directions must be checked for the individual property and proposed work.