House Extensions London

House extension specialists in North London

If you live in London or Hertfordshire, adding an extension to your house, whether it's a side return, wrap-around or a rear extension, gives you more space and increases the value of your property. At Marriott Construction, we offer two types of building packages. Design and Build house extensions in north London - when our architect works closely with you to prepare the architectural and structural drawings and then starts the building process by submitting the plans to your Local Authority. Once the application is approved, our skilled builders in north London will complete your home extension to the highest standards. If you already have hired architects to do the design, we can extend your home following their drawings and specifications.

Upon completing the construction of the extension, we provide our clients with the building completion certificate, and a ten-year structural warranty comes as standardAs one of the best building contractors in North London, we have built many home extensions in London and Hertfordshire, which show the expert services provided to our clients by our professional extension builders. Book a free no-obligation consultation today and benefit from our experience by letting our team of experts help you find some of the best solutions to the space problems in your North London property. 

Extensions to houses in North and North West London

Rear house extension in London

Rear house extensions

Our client wanted to add an extra room to bring some light into his house and express his personality. Our extension builders achieved the objective by adding a rear house extension to this property in North London. The brick walls helped the expansion fit with the surroundings.

Kitchen extension in North London

Single storey extension

Our clients wanted to build a larger kitchen that would also help bring more light into their North London home. Using only the best materials, our extension experts added this kitchen extension to the house's back. The Velux roof windows helped brighten the house interiors.

Two storey extension in North West London

Double storey extension

Our client decided to build a two-storey extension. As this property in north London sits on a slope, the project architect designed a home extension with a half basement and sliding glass doors. Our builders, who have years of experience in this field, completed the building process following the plans.

House Extension Design

When it comes to designing the best house extension for your house, start by considering whether you want to build a single or a double-storey extension with a flat or a pitched roof. To get an idea if your extension plans are likely to be accepted, take a look around your area to see what types of extensions other people have built. Your house extension design might even qualify under the Permitted Development, in which case you will not need to apply for Planning Permission. A good architect or London design and build contractors should be able to offer free advice regarding planning and building permissions. 

Building a home or a kitchen extension in London is comparatively cost-effective, so without having to move or buy a new house, you can opt for this kind of renovation and get a new room or the kitchen you like. With our versatile service extension in north london, our experienced team of architects, building experts and interior design specialists work with you, taking into account your style preferences to add the perfect kitchen or living space to your property.

Single storey wrap around extension in London

Single Storey House and Kitchen Extensions

A single-storey extension is a popular type of home improvement project, as it visually connects the house with the garden. There are three kinds of one storey extensions: rear, side return and wrap-around. (pictured).

While most single storey rear and side return house extensions qualify under the Permitted Development, a wrap around extension always requires Planning Permission. Our North London house extension builders could help you add space to create a large open-plan kitchen while making a connection with your back garden, a bright lounge area with a fireplace, or a gym. 

Double storey house extension in Hertfordshire

Double Storey House Extensions

A double-storey house extension might be more cost-effective than a single storey, as the roof and the foundations usually tend to be the most expensive parts of the build overall. 

Our north London builders, who have years of experience, could add a two storey extension to the back or the side of your property. In order to comply with regulations, two-storey side extensions usually need to have a pitched roof similar in design to the existing one. You could go for a kitchen extension, and add an extra bedroom, a playroom, or an office upstairs.

Extending a House FAQs

If you have any questions regarding our London home extension services or would like to request a free consultation with our expert extension builders, contact us today!

Our client's satisfaction is our number one priority. We have teamed up with several architects and interior designers including award-winning Alan Cox Associates, to offer a 3D visualisation of your London extension plans, as well as interior design services if required. 

A house extension cost will mostly depend on the quality of the finish and the materials used. While basic extensions in London can be as cheap as £2000 per square metre, if you want to build a top quality high end extension, the cost can go up to £5000 per sq. m.

High-quality home extensions can increase the value of your North London or Hertfordshire property by up to 25 per cent, which exceeds the expense.

A small one storey rear or side extension can be completed within three or four months. Wrap-around extensions and larger rear and side return extensions will take slightly longer to build. A double-storey extension might take up to nine months to complete.

House extensions are growing in popularity as house renovation projects due to the high demand for larger homes. It is an innovative and affordable construction method for specialist builders and the homeowners who decide to add extra space to their property. The different types of house extensions can get you many benefits. As well as the obvious advantages for you and your family of an extension, such as more space to co-habit in, it can also add light to your London home, making it look brighter and more welcoming. 

The most common and popular uses for house extensions in London are:

  • Extending the back of the property into an open plan kitchen and dining area while utilising garden space by bringing the outdoors in.
  • Creating an additional bedroom, games room, playroom, home office or gym.
Building a house extension in London FAQs


Rear House Extension

Great project management delivered on time and on budget. Imaginative solutions in problem solving. Very high standard of finish. Very tidy site throughout the build. Prepared to go the extra mile.


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  • 183 Edgware Road
  • London
  • NW9 6LP
  • 2 Athenaeum Road
  • Whetstone
  • N20 9AE

0208 205 8173 - Mon to Fri 09:00 - 17:00

We operate across North London, North West London and Hertfordshire including BarnetBushey, Camden, Edgware, Finchley, Hampstead, Hendon, IslingtonMill Hill, Potters BarStoke Newington and Watford