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Loft Conversion Architect

Each property is unique in terms of plan form, orientation, adjoining owners and historical additions. A loft should be a genuinely fantastic addition to a property. At Atelierdb we analyse the existing arrangement and advise on the best route to maximise the design and spatial potential of the loft. This can sometimes be via a Permitted Development application and/or a Planning application. Both offer subtle differences which are very important to have fully explained at design stage so the right choices are made to ensure the budget is best spent.

Permitted Development Loft Design

Permitted Development lofts can usually be easily spotted due to some key visual elements:

  • ridge of house not raised
  • vertical rear facades (boxy designs)
  • materials are in keeping with the host property
  • whilst internally they visually  ‘tick the box’, externally they can appear ill-fitting and awkward

A loft undertaken using ‘PD’ must add no more than 40m3 to a terraced property or 50m3 on a semi-detached or detached property.

Adding a loft to the main portion of a period property will typically use up around 27-29m3 of the ‘PD’ allowance. This then leaves 11-13m2 of volume allowance to extend over a rear projection/outrigger which wont achieve much.

Oddly it is possible to achieve some design elements using ‘PD’ that would not be possible if applying under a Householder Planning Application. An example of this is regarding vertical facades to the rear elevations – a Household Planning Application would most likely require these facades to be designed as 70′ mansard roofs. When ‘PD’ is used, the Planners have no say over this design element – which internally wins additional space. Similar design ‘wins’ can be had when undertaking hip-to-gable conversions. When working with clients we advise on which route will achieve the best outcome to maximise the properties potential.

Householder Planning Application Loft Design

Sometimes it is not technically possible to use Permitted Development as the best option for a Loft Extension. This can occur when there is a need to create a loft in excess of the allowed cubic metre allowances, or when the ridge height needs to be raised. Atelierdb are highly skilled to be able to appraise and advise on which application route, or combination of applications, will achieve the required brief.

Planning Officers will refer to a number of issues when reviewing a Householder application:

  • local context and precedent within the surrounding terrace. looking for any emerging patterns can help to justify similar proposals if preferred. For example, if a property is the last remaining in a row having not undertaken a loft conversion with all others being constructed with vertical facades, a Case Officer would likely not insist a 70′ mansard be constructed – even if this was written in a Policy document from their Planning Department.
  • sense of enclosure and loss of outlook. adding a loft over a rear outrigger can impact significantly on shared side return areas. this again supports the design having 70′ mansard roof which is felt help to lessen a sense of enclosure.
  • loss of light. any addition at loft level must not cause loss of light to adjoining habitable rooms. case officers sometimes undertake their own BRE daylight assessment of such situations, but they can also request the applicant provide a Light Survey report to ensure that no loss of light is being caused by proposed loft additions.
  • hierarchy and subserviency. case officers will wish to see the design respect the original host property. this can be achieved by setbacks on plan, material changes and again 70′ mansard roofs.
  • overlooking. any new windows at loft level must not give rise to any privacy issues. normally rear facing windows are acceptable. side windows should follow the principles as stipulated in Permitted Development, being obscure and only openable above 1.7m from floor level.

Each application is reviewed on its own context, but with reference to Planning Guidance Documents. There can be at times a lack of continuity within the same Planning borough, with some full length extensions over outriggers being allowed, but some restricted to 50% of the outrigger. A carefully prepared Design&Access support document should  be provided with any application when trying to deviate away from standard guidance.

Planning departments have an active wish to support good design. Over the years we have created some amazing loft conversions both under Permitted Development and Planning routes.

Insulating a loft

A loft should provide a comfortable environment through all 4 seasons of the year. Whilst this may seem an obvious statement it is alarming how many lofts are constructed incorrectly.

The correct design principles need establishing at Design Stage and identifying in a Planning Application by showing correct thicknesses and buildups. A warm roof must only ever be installed. These have a continuous layer of insulation above the structural joists. The depth of insulation has increased significantly as homeowners and Building Regulations seek to improve energy loss and reduce heating bills. Good insulation is not only critical for winter but summer too.

Naturally a loft will become hot during the day given heat rises up through the house. Atelierdb designs consider these basic but important details and design in ventilation solutions to allow any heat buildup to be managed. Having well installed insulation in the front pitched roof, flat roof and vertical or mansard walls must be executed correctly with associated vapour control layers to provide a comfortable loft space for years to come.

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    We used Atelierdb to design and project manage our kitchen extension. We found David extremely professional and with great attention to detail. The design process was tailored and iterative to ensure we met our objectives wherever possible, and the project management service was invaluable to keep us on track (and sane!) during the building works. We are now delighted with the new living space that it has achieved for us.

    — Zoe Lelliott


    It has been an absolute pleasure working with Atelierdb from the initial planning and design of the project right through to completion. Not only did they deliver on the brief, they managed to exceed our expectations on what could be done to the space (whilst staying within budget!). The entire process remained stress-free thanks to the ongoing communication between Atelierdb and the building contractor, allowing the project to be completed on time and to a very high standard. Highly recommended.

    — Danny and Lara Moody


    We appointed Atelierdb to re-design our house prior to a full renovation. We were extremely pleased with the service, David and his team provided many layout possibilities, they were flexible and professional throughout and always had solutions. I would highly recommend them.

    — Jennifer Pitt

    Heaver Estate Conservation Area

    We're very happy with the basement living space which was created as part of a larger renovation of the property. atelierdb helped us focus on the relevant issues at the relevant time and were particularly diligent in administering the building contract.

    — Stewart Quinn

    Northcote Road Battersea

    We have recently completed our kitchen extension project and I can only recommend David and his team. The support and patience during the design phase was great and the project management and support during the construction has been really helpful. They turned an idea into an amazing living space.

    — Michela Bariletti


    We have since moved into a larger property and project and we are now working with atelierdb for the second time.

    — Carol O'Gorman