Double Storey Extensions London

If you love your home but need more space, adding an extension or having a loft conversion makes good sense. You can stay where you are, increase your living space and add value to your home at the same time. 

If your prime concern is to expand your kitchen and family living areas, then a ground floor single storey extension may well be enough. But if you need an extra master bedroom or two, plus an additional bathroom, or just a home office away from the busy ground floor, then a double storey extension is ideal.

Are all double storey extensions the same?

There are numerous permutations of a successful double storey extension, including:

• a straightforward double storey rear extension on two floors, projecting back from the rear of the house – a double storey rear extension
• a side return extension (sometimes called an infill extension) which uses the outside space next to the original rear ‘outrigger’ extension in L-shaped properties
• a double storey side extension
• an L-shaped extension incorporating space at the side of the house as well as the back

Why choose a double storey extension?

The need for extra space is obviously an important driver in your decision, and a double storey extension significantly increases the opportunity to re-model part of your home – ideally with beneficial results elsewhere in the property too. 

A double storey extension in London comes with important advantages, including:

• the new upstairs accommodation will give you much greater flexibility for bedroom accommodation generally, especially if you include an additional bathroom too
• the extended ground floor provides more than an opportunity to remodel a kitchen and/or living area – structural changes will be needed anyway, so you can also make other changes on the ground floor
• a double storey extension is cost effective – the foundations required for the two storey extension are very similar to those needed for a ground floor only extension; the double storey extension costs per square metre will therefore be less for a two storey extension.
• Building up as well as out means you need to take less of the garden for the same increased floor area.
• Often the upper level of the extension will be stepped back, to avoid it blocking light from neighbours, and this gives you the opportunity to include skylights or larger glazed sections in the roof of the ground floor section.
• A double storey extension can add considerable value to the property, both in terms of total floor area and in sale value. It is difficult to generalise how much extra value will accrue, of course, as much depends on the size of the extension and the location. Depending on where you look, you’ll find figures from an additional £4000 to £6000 per extra square metre. Therefore, in comparison to the initial cost of a two storey extension, you could recoup the costs of two storey extension once you decide to sell. However, on this point, it is always best to take advice from local estate agents and monitor the property market before you sell.

You’ll see from this that while Permitted Development Rights do allow for a wide range of structures, Planning Permission opens up numerous opportunities in terms of scale and design. You might wish, for example, to have an extension designed to contrast with the existing building rather than match it, in which case Planning Permission is required.

Even with Planning Permission, the double storey extension will almost certainly need to be no higher than the existing roof line, so this may lead to lower ceilings on the new first floor compared to the ground floor. Likewise, the size and shape will need to be such that the extension does not loom over neighbouring homes, nor block off their light. If you live in a terraced or semi-detached home you’ll almost certainly need a party wall agreement too.

When balancing these criteria it is wise to enlist the support of a Planning Specialist, and ideally one working in or with your architectural designers – this will keep everything under one roof and ensure a holistic approach to the whole project.

Keep track of the details, without losing sight of the big picture.

Once your ideas have begun to crystallise, you’ll need a feasibility study to bring together all your ideas. Take advantage of the practical expertise of architectural designers, structural surveyors and also party wall surveyors if relevant. At this stage you can consider overall design (shape, style of roof and windows, room sizes etc) and materials and internal finishings.

A good feasibility study will include:

• advice as to the pros and cons of Permitted Development Rights compared to Planning Permission.
• ideas for overall design and style, with recommendations for materials to suit your purpose and budget
• recommendations as to the best choice of roof style and windows – eg, sliding or bi-fold doors on the ground floor, Juliet backlines on the first floor
• room layouts and consequences for wiring, plumbing and heating
• initial drawings (with plans and 3D visualisations)
• advice on Building Regulations and Building Control (the inspection side of Building Regulations)
• initial estimates as to costs.

Do remember that if your home is a listed building, or if you live in a Conservation Area, there will be specific restrictions in addition to the usual Planning requirements.

When the basic shape of your project is agreed, your architectural designers can start on the detailed planning and preparation for your two storey extension. You’ll be able to agree detailed specifications and get the paperwork started to support your Application for Planning Permission or your request for a Lawful Development Certificate – that will confirm your Permitted Development Rights if your project qualifies.

We do house extensions all over London. Areas include (but are not limited to): Barking & Dagenham, Bromley, Barnet, Bexley, Enfield, Greenwich, Hammersmith & Fulham, Havering, Romford, Thurrock, Twickenham, Waltham Forest, Wandsworth, Walthamstow, Richmond,  High Wycombe, Harrow, and Ealing.