Roof extensions
London architect guide
Inspiration and ideas
Roof extensions are the most cost-effective way to maximise the floor area of your house or flat when compared to adding the same floor area with a rear or side extension.
As part of this Roof extensions London architect guide we have selected some projects to lend architectural inspiration and design ideas for your roof extension or loft conversion.
You can read here our latest Loft conversion cost planning permission architect guide for everything you need to know about your loft conversion project.
Roof extensions London architect guide – Design aspirations and key considerations

Architect designed residential extension Stoneleigh KT17 by GOAStudio London residential architecture – View from Master Bedroom
Designing the staircase is the single most important thing we will need to consider for any type of roof extension or loft conversion as your roof extensions London architects and experts.
There are Building Regulation restrictions in regards to the risers, goings, and head heights with regards to the staircase. There are fire regulations to consider as well, and plumbing/drainage issues to take into account when an en-suite is to be created. The design challenge is about how to exercise intelligent space planning around all the relevant restrictions so that both the new loft layout and the layout of the floor below do not get compromised when the staircase is added to the existing floor plan.
Start considering how you would like to use your new space, and how it will interact with the rest of your home. It is important that the new extension blends with the rest of the building and is easily accessible, so when considering the staircase think about its long-term use as much as its style.
During the design development stage we will get to explore lots of ideas, but you can start the process now by considering answers to questions like these:
- “How can we best use this new room? Will it be our new master-bedroom, a study space, a nanny’s room? What other bedrooms are available in the house, and what would work best for our changing needs and family?”
- “Space permitting, how about adding an en-suite, a walk-in wardrobe, or even a coffee area in front of a Juliet balcony?”
- “What do we think about rooflights in the bedroom? They bring more light into the room but how about the rain ticking on the glass, is it charming or just plain annoying?”
Roof extensions London architect guide – Types and options for your home project
There are four main types of loft conversion that might be possible for your property; note that a lot depends on the type of the original roof and the relevant planning policy guidelines for your area.
Dormer window extension | The simplest way of extending your roof area is by adding dormer windows, creating some additional space and bringing light into this area which can form a new bedroom or study.
Partial or full extension of roof at rear | A partial or full extension of the roof at the rear will give you considerably more space should planning permissions allow. A lot also depends on the existing head height in your loft. The more the maximum head height the more useful a floor area you will be able to add with your roof extension.
Side hip-to-gable roof extension | For detached and semi-detached houses this extension offers significant opportunities for expansion subject to the Permitted Development Rights your property might have.
Mansard roof extension | This is appropriate for properties with what is commonly known as “butterfly” or “V” roofs. Such roof extensions practically add a full new level to your property and they can be the perfect solution to houses or flats in conservation areas. The planners will take a view on whether a mansard roof can be added. And here is the rule of thumb when it comes to planning: if the majority of the properties in your terrace have mansard roofs then it is likely the planners will approve an application for a mansard roof to your property.
Your local authority will have restrictions in place about how much you can extend, and part of our job is to achieve the maximum potential for this valuable type of home extension. For houses with Permitted Development Rights a larger roof extension will be possible, and this is the first thing for us to have a look at before we start the design development process.
BOROUGH SPECIFIC ARCHITECT AND PLANNING GUIDES FOR YOUR HOME PROJECT
Your local Council will have in place design and planning requirements for your home project and you will need to obtain planning approval for a wide range of extensions and alterations to your property.
When you get in touch we will offer you detailed advice about what is likely that your Council will approve and in the meantime we have prepared the following architectural and planning guides that include extracts of the relevant planning policy and examples of our projects in our Borough.
Barnet residential architect and planning guide, Camden residential architect and planning guide, Enfield residential architect and planning guide, Hackney residential architect and planning guide, Hammersmith Fulham residential architect and planning guide, Haringey residential architect and planning guide, Hounslow residential architect and planning guide, Islington residential architect and planning guide, Kensington and Chelsea Conservation architects, residential and planning guide, Lambeth residential architect and planning guide, Lewisham residential architect and planning guide, Newham residential architect and planning guide, Redbridge residential architect and planning guide, Richmond residential architect and planning guide, Tower Hamlets residential architect and planning guide, Waltham Forest residential architect and planning guide, Wandsworth residential architect and planning guide, Westminster residential architect and planning guide
HOME DESIGN
See our guides for ideas, inspiration and architectural advice for your home project.
Side extensions London residential guide, Rear extensions London residential guide, Kitchen extensions London residential guide, Roof extensions London residential guide, Residential renovations London guide, Mansard roof extensions London residential guide, Contemporary extensions London residential guide, Flat extensions London residential guide, Garden flat extensions London residential guide, House extensions London residential guide
Also see our latest Conservation area architects - London architectural and heritage guide and Listed Building architects - London architectural and heritage guide.
We have prepared a guide on the type of Architectural plans you will need for your home project, and another guide for Terraced house extension plans that includes advice on detached and semi-detached properties as well.
ARCHITECT SERVICES
See what we can do for you.
Introducing GOAStudio London residential architecture limited
“George Omalianakis Architecture Studio – GOAStudio London residential architecture” was set up in 2009 to provide architectural services and assist home owners with their residential projects across London.
George Omalianakis is a multi-award winning chartered architect with the Royal Institute of British Architects (RIBA), registered with the Architects Registration Board (ARB), and has extensive experience in working on a variety of residential, commercial and educational sectors.
Which? magazine residential expert and contributor. Ideal Home magazine residential expert and contributor. Member of the Green Register of Construction professionals.