How Much Will My Ground Floor Extension Cost?

House extension companies in London should be able to tell you rough estimates for generic ground floor extensions. In London, period properties are, for the most part, similar in layout and size. There are absolutely exceptions – and these should be quoted for separately. If you have a 4-5m wide Victorian or Edwardian terraced or an end of terrace property, the costs discussed in this blog should be relevant to you. 

We thought we would run through some of the typical ground floor extensions that we undertake here at Home Tales, as well as the associated costs for each option. Did you know we also have a fantastic information page on general costs of home extensions in London on our website which you can read here.

Side return extension

Side return extensions in London are one of the most popular extensions that we undertake here at Home Tales. In London, side returns often feature on terraced properties. This area is often seen as wasted space, as it doesn’t add much to the garden value due to its awkward narrow shape and restricted size. Encompassing this outside area within the property can completely transform the home for two reasons. Firstly, it adds SQM area onto the room, increasing the width and creating one large room to the rear of the property. This room often spans the full width of the property and as a result, opens a whole host of possibilities for a kitchen, dining and/or living area. Secondly, it enables the insertion of more glazing within the home. Velux windows, all-glass roofs, windows, and full width glass doors overlooking the garden all contribute to improving the rooms general feel and ambience. 

A typical side return extension requires steel to be inserted along the supporting wall of the property (the wall that you are removing), as well as another steel towards the rear to open-up the rear opening. For a typical side return extension on a property between 4 to 5m in width, the build cost for a watertight shell with a standard glazing package (bi-fold doors to the rear and Velux windows along the side return), would be about £60-70k plus VAT. 

We recently completed a side return extension in Wandsworth. The property width is 4.5m and the finished rear room size is 6m in length. The existing layout was a little different from a typical period property, as stud walls had been inserted to create a separate little kitchen from the rear room. We removed all of these walls and extended into the side return, creating this wonderfully large room. The room is large enough to house a large kitchen island, spacious kitchen and a 6-seater dining table. The homeowner opted for these crittal style doors which are made from aluminium. These give you that crittal appearance for a fraction of the cost. We used 3 large Velux windows along the roof of the side return to help catapult natural light deep into the room.  

Rear extension 

If you don’t have a side return and if your property is flush to the rear, then you can opt for a rear extension. In this case you will still get that lovely full width rear room (spanning 4/5m in width). In this case the rooflights tend to go on the roof of the rear extension, rather than on the side of the property. Velux windows, architectural skylights and roof lanterns are both wonderful options and are very effective at getting natural light into the property. This type of extension will cost around £55-65k + VAT. 

We recently extended this stunning property to the rear by 3.5m in SE19, Croydon. The extension completely transformed the property and allowed for a spacious kitchen and dining area. We inserted a stunning rooflight over the dining table which helps zone the area. We inserted LED trim into the plasterwork which makes the rooflight a feature at night too. 

Wraparound extension 

Wraparound extensions are a combination of the two extensions described above. As a result, they are the most expensive. On the other hand, they also add the most SQM to the property.  

Large wraparound extension 

We recently obtained permission to extend into the side return of this property as well as a 4m rear extension. This will finish with a room size of approximately 10m in length and 5.5m in width. This allows enough room for a WC and utility room, a spacious kitchen with a large kitchen island, a dining area and a living area. A wraparound extension of this size will be around £85-95k + VAT. You have to allow for more complex steel as the internal area is so large. It’s also worth considering the final fittings will be more expensive too as there is so much space to fill! Remember to account for the flooring material, the larger kitchen, and more glazing on the roof. 

Medium wraparound extension 

The case study mentioned above is very large – so we thought it might be useful to give you an example of a medium wraparound project too. We removed an existing conservatory on this property and extended to the side and rear. The cost of this extension was £60-70k + VAT. 

If you are considering a home extension, get in touch with our team today on 0207 043 2378 or email us at We would love to discuss your individual project in more detail. Telephone consultations enable us to discuss the details of your specific project, which means that we can issue you with a quote for the works based on your individual requirements. You can book a consultation directly via our live bookings page here. We look forward to hearing from you. 

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