Design guidelines for mansard roof extensions

The council is seeking feedback on a proposal to adopt mansard roof design guidelines for three conservation areas, Clinton Road, Ropery Street and Tredegar Square. The council also plans to update existing guidelines for Driffield Road and Medway conservation areas. If approved, the guidelines will help residents to get planning permission to extend their homes upwards with a mansard roof.

What is a mansard roof?

A mansard is a type of roof that features two slopes on each side, the lower slope is steeper, and the upper one is shallower. They are used to provide an extra living space within the roof, while limiting the impact on the streetscape by partially hiding the new roof structure behind the front parapet wall.

Why are the guidelines needed?

In the past, the council has discouraged adding mansard roof extensions to many properties in conservation areas due to concerns about the impact they have on the historic environment. However, in 2017 the council adopted mansard roof guidelines for Driffield Road and Medway conservation areas. This was because many residents told us that they would like greater flexibility to extend their homes to accommodate growing families or adapt to changing circumstances.

Since then, we have heard from residents in other areas, who would welcome a similar approach. As a result, the council is now considering extending the approach to three more conservation areas. At the same time, the council is proposing to update the existing guidelines for Driffield Road and Medway conservation areas, the design principles will remain the same, but they will be made clearer and easier to use, with some additional information.

Which buildings will the guidance cover?

The council has prepared new draft guidance for Clinton Road, Tredegar Square and Ropery Street conservation areas, and updated guidance for Driffield Road and Medway conservation areas.

The guidance shows exactly which properties in these areas it applies to. Not all buildings in the conservation areas are suitable for mansard roof extensions. This may be because a different type of roof extension is more appropriate. Some buildings may not be suitable for any kind of roof extension at all, this may include buildings that are statutory or locally listed, which have additional heritage sensitivities.

What does the guidance contain?

The guidelines have been developed by the council in conjunction with specialist conservation architects. They explain in clear visual terms how a mansard roof extension should be designed to ensure that it harmonises with the original building and minimises harm to the character and appearance of the conservation area. It covers things like how to:

• set the extension back to reduce visual intrusion
• design appropriate dormer windows
• treat chimney stacks
• design rainwater drainage
• best achieve a suitable stairwell head height
• incorporate solar panels.

The guidelines also set out how the council will manage harm to the character and appearance of the conservation areas that arises from the introduction of mansard roof extensions.

How will the council manage harm to the historic environment?

The residential streets of these conservation areas typically have a consistent architectural form with a strong uniform roofline that makes a positive contribution to the character of the area. The introduction of mansard roofs can disrupt and cause harm to this, even where they are designed in accordance with the council's guidance. To help mitigate this harm, the council proposes that roof extensions are accompanied by enhancement works to the front of the host building, that will improve the character and appearance of the area. The council also suggests that proposals for mansard roofs are accompanied by a commitment to make a financial contribution to a streetscape improvement fund. This will be used to deliver public realm improvements that will help to further offset the harm from mansard roof extensions.

How can I get involved?

We would like to hear your views on the proposed new and updated mansard roof design guidelines. In particular, we are keen to understand the level of resident support for the proposal to permit mansard roof extensions in these conservation areas. Links to the guidelines can be found in the ‘consultation documents’ section of this page. There is a separate document for each conservation area. Each set of guidelines is accompanied by a character appraisal and management plan document. These describe the area’s architectural and historic character and explain how it should be managed in the context of appropriate ongoing change. They address various development issues and are relevant here as they help set the scene for the proposed approach to mansard roof extensions.

Hard copies of these documents are also available for you to view at Bow Idea Store on Roman Road and at Tower Hamlets Town Hall on Whitechapel Road. Please ask at reception if you would like to see one of these hard copies.

Please send us any comments you have about the draft guidelines, or the character appraisal and management plan documents to placeshaping@towerhamlets.gov.uk or, if you prefer, you can send them by post to:

The Place Shaping Team

Planning & Building Control

Tower Hamlets Town Hall

160 Whitechapel Road

London

E1 1BJ

When sending your comments, please let us know if you are a resident of one of the conservation areas. All personal information treated as confidential and will be processed in accordance with the General Data Protection regulation and UK privacy legislation.

Please make sure your comments reach us by Sunday 27 October 2024.

What if I have questions about the guidelines?

Please see the frequently asked questions section of this page. We will add to this section as the consultation progresses.

If enough residents are interested, the council will also organise drop-in information sessions where you can speak to a council officer and ask any questions you may have about the proposed guidelines. Please contact us at placeshaping@towerhamlets.gov.uk if you are interested in attending one of these sessions.

What will happen after the consultation?

The council will carefully review all consultation responses before deciding whether to approve the guidelines or amend them before approval.

The final decision on the guidelines will be made by the Mayor at a Cabinet meeting, which will be open to the public.