Share this
What does it cost to extend your home?
by RISE Design Studio on Sep 12, 2018
We’re often asked how much a house extension costs in London. Extending the home is a popular option among clients who perhaps need another bedroom, an office space, or a living area, without the hassle (and stress) involved with moving house. Although home extensions in London generally cost more than elsewhere in the UK, they remain a viable and cost-effective option to create your ideal additional living space and increase the value of your home. In this post, we set out the main costs associated with a house extension project.
Extending into the garden and optimising natural light
You generally have three options for extending your home: single storey, two storey or basement. The construction cost of extending the ground floor of your home (in a single storey) is, as a general rule, between £2,200 and £3,900 + VAT per square metre, depending on the level of the specification you decide on. This is a popular option for extending into the back garden to add a dining area, studio or additional living space. It is also an excellent way to bring more natural light into the property, with the ‘glazed envelope’ (like the one in the above image) making the new space feel very spacious and ‘open’. If you plan to use the new space for a kitchen or bathroom then the cost of the fitting will need to be included (typically expect an additional £10,000 + VAT for a kitchen [low-mid level of specification] or £5,000 + VAT for a bathroom [mid range]).
The value of two floors
A two-storey extension generally costs an additional 50% of the construction cost of a single storey extension. It gives you the option of adding an upstairs bedroom or other room and the investment will seem like good value as once the foundations and other structural supports are in place, you do not need to bear these costs again for the second storey. It is important to note that a two storey extension may impact on the amount of light reaching your garden and may also present additional complexity in the planning process (achieving consent for a two storey is often more difficult that for a single storey and sometimes not permitted at all for example in a Conservation Area).
Going underground
A basement addition tends to be the most expensive option per square metre because of the structural and construction complexity and risk. The construction cost of a new space in your basement in London is likely to amount to between £4,000 and £5,000 + VAT per square metre. The costs may be less if you have an existing basement which may instead need converting or extending partially.
Other costs to consider
In addition to the estimated costs set out above, you will also need to factor in the cost of the professional services that you require, such as an architect and any other consultants that you need to involve – for the majority of projects you’ll need a Structural Engineer, Party Wall Surveyor, Building Control Approved Inspector and sometimes a Mechanical & Electrical Engineer as well as a Quantity Surveyor. This typically adds 15-28% to the construction cost. There are also planning fees (£200 to £300 for a house extension, although some extensions may fall under Permitted Development Rights), home insurance costs, and VAT. The costs of windows, doors and central heating will also be in addition to the costs already listed.
Site access and other constraints
There can also be costs associated with mitigating the constraints of a site. For example, the soil type may affect the type of foundation required or the types of building material that can be used, or there may be trees, drainage or other pipework that need to be (re)moved to allow access. If your property is listed and/or situated in a conservation area, you will need to allow for higher costs overall.
Despite the long list of costs, a home extension can greatly improve your living space and also increase the value of your home by 10% to 30%. We take pride in the home extensions that we have completed for our clients and it is always a pleasure to bring more light and space into the home. You can browse some of our recent residential projects here. If you would like to discuss a potential project with us, please get in touch.
Share this
- Architecture (146)
- Sustainable architecture (85)
- Design (66)
- Retrofit (55)
- Passivhaus (53)
- London (51)
- New build (48)
- Renovation (41)
- energy (38)
- interior design (37)
- Sustainable Design (34)
- Planning (32)
- Environment (31)
- Building materials (30)
- climate-change (29)
- Inspirational architects (27)
- Refurbishment (27)
- extensions (27)
- Building elements (22)
- Inspiration (21)
- Rise Projects (16)
- enerphit (16)
- Extension (13)
- net zero (13)
- General (12)
- Philosophy (12)
- Carbon Zero Homes (11)
- Working with an architect (10)
- architects (10)
- Awards (9)
- Innovative Architecture (9)
- London Architecture (8)
- RIBA (8)
- architect (8)
- Airtightness (6)
- Eenergy efficiency (6)
- Uncategorized (6)
- Virtual Reality (6)
- RISE Sketchbook Chronicles (5)
- Sustainable (5)
- cinema design (5)
- ARB (4)
- BIM (4)
- Basement Extensions (4)
- concrete (4)
- local materials (4)
- modular architecture (4)
- working from home (4)
- Carbon Positive Buildings (3)
- Home improvement (3)
- Passive house (3)
- Permitted development (3)
- Planning permission (3)
- Property (3)
- circular economy (3)
- construction (3)
- mvhr (3)
- natural materials (3)
- plywood (3)
- structural (3)
- structuralengineer (3)
- Artificial Intelligence (AI) (2)
- Bricks (2)
- Building in the Green Belt (2)
- Costs (2)
- Covid-19 (2)
- Heat Pumps (2)
- Home extensions (2)
- Permitted development rights (2)
- Residential architecture (2)
- Roof extension (2)
- Social Distancing (2)
- Welbeing (2)
- ashp (2)
- barcelona (2)
- building information modelling (2)
- co-working (2)
- design&build (2)
- furniture (2)
- glazed-extensions (2)
- green architecture (2)
- greenbelt (2)
- historic architecture (2)
- light (2)
- living space (2)
- london landmarks (2)
- londoncinemas (2)
- openingupworks (2)
- peter zumthor (2)
- rammed earth (2)
- self build (2)
- sustainability (2)
- sustainable building (2)
- traditional (2)
- trialpits (2)
- #NLANetZero (1)
- 3D Printing (1)
- 3D models (1)
- Adobe (1)
- Alvar (1)
- Architecture Interior Design (1)
- Area (1)
- Art (1)
- BIMx (1)
- BREEAM (1)
- Bespoke lighting (1)
- Birmingham Selfridges (1)
- Boat building (1)
- Boats (1)
- Brass (1)
- Brexit (1)
- Building energy (1)
- Casting (1)
- Chailey Brick (1)
- Chartered architect (1)
- Commercial Architecture (1)
- Copper (1)
- Czech Republic, (1)
- David Lea (1)
- Dormer extension (1)
- Ecohouse (1)
- Fees (1)
- Flooding (1)
- Furniture design (1)
- Gandhi memorial museum (1)
- Garden studio (1)
- Green Register (1)
- Green infrastructure (1)
- History (1)
- House cost (1)
- India (1)
- Jan Kaplický (1)
- Kitchen Design (1)
- L-shaped dormer (1)
- Land value (1)
- Loft conversion (1)
- Lord's Media Centre (1)
- Mapping (1)
- Marseilles (1)
- Mary Portas (1)
- Metal (1)
- Micro Generation (1)
- Monuments (1)
- Party Wall Surveyor (1)
- Place (1)
- Porch (1)
- Prefab (1)
- Procurement (1)
- Richard Rogers (1)
- Sand (1)
- Scandinavian architecture (1)
- Selfbuild (1)
- Social housing (1)
- Spain (1)
- Steel (1)
- Surveying (1)
- Sverre fehn (1)
- VR (1)
- West london (1)
- Wildlife (1)
- Wood (1)
- architect fees (1)
- architectural details (1)
- arne jacobsen (1)
- avant garde (1)
- backland (1)
- basements (1)
- brentdesignawards (1)
- building design (1)
- building regulations (1)
- built environment (1)
- carbonpositive (1)
- cement (1)
- charles correa (1)
- charles eames (1)
- charlie warde (1)
- charteredarchitect (1)
- climate (1)
- climate action (1)
- codes of practice (1)
- collaboration (1)
- constructioncosts (1)
- country house (1)
- countryside (1)
- covid (1)
- dezeenawards (1)
- drone (1)
- eco-living (1)
- emissions (1)
- epc (1)
- finnish architecture (1)
- foundations (1)
- futuristic (1)
- georgian architecture (1)
- glazed envelope (1)
- good working relationships (1)
- green building (1)
- hampstead (1)
- happiness (1)
- health and wellbeing (1)
- home extension (1)
- homesurveys (1)
- house extension (1)
- imperfection (1)
- independentcinemas (1)
- innovation (1)
- inspirational (1)
- insulation (1)
- interiorfinishes (1)
- internal windows (1)
- jean prouve (1)
- kindness economy (1)
- kintsugi (1)
- landscape architecture (1)
- lime (1)
- listed buildings (1)
- local (1)
- lockdown (1)
- low carbon (1)
- mansard (1)
- manufacturing (1)
- materiality (1)
- modern architecture (1)
- moderninst (1)
- modernism (1)
- moulded furniture (1)
- natural (1)
- natural cooling (1)
- natural light (1)
- nordic pavilion (1)
- northern ireland (1)
- palazzo (1)
- placemaking (1)
- planningpermission (1)
- plywood kitchen (1)
- post-Covid (1)
- poverty (1)
- powerhouse (1)
- preapp (1)
- preapplication (1)
- project management (1)
- ray eames (1)
- reclaimed bricks (1)
- recycle (1)
- renewable energy (1)
- reuse (1)
- ricardo bofill (1)
- rooflights (1)
- room reconfiguration (1)
- rural (1)
- satellite imagery (1)
- selfbuildhouse (1)
- shared spaces (1)
- site-progress (1)
- solarpvs (1)
- space (1)
- stone (1)
- structuralsurvey (1)
- sun tunnel (1)
- sustainable materials (1)
- terraces (1)
- thegreenregister (1)
- totality (1)
- wabi-sabi (1)
- waste (1)
- wooden furniture (1)
- zero waste (1)
- December 2024 (1)
- November 2024 (8)
- October 2024 (5)
- June 2024 (1)
- May 2024 (1)
- March 2024 (1)
- February 2024 (1)
- January 2024 (2)
- November 2023 (1)
- October 2023 (5)
- September 2023 (7)
- August 2023 (7)
- July 2023 (6)
- June 2023 (8)
- May 2023 (14)
- April 2023 (11)
- March 2023 (8)
- February 2023 (6)
- January 2023 (5)
- December 2022 (3)
- November 2022 (3)
- October 2022 (3)
- September 2022 (3)
- July 2022 (2)
- June 2022 (1)
- May 2022 (1)
- April 2022 (1)
- March 2022 (1)
- February 2022 (2)
- January 2022 (1)
- November 2021 (1)
- October 2021 (2)
- July 2021 (1)
- June 2021 (1)
- May 2021 (1)
- April 2021 (1)
- March 2021 (1)
- February 2021 (1)
- January 2021 (2)
- December 2020 (1)
- November 2020 (1)
- October 2020 (1)
- September 2020 (2)
- August 2020 (1)
- June 2020 (3)
- April 2020 (3)
- March 2020 (2)
- February 2020 (3)
- January 2020 (1)
- December 2019 (1)
- November 2019 (2)
- September 2019 (1)
- June 2019 (1)
- April 2019 (2)
- January 2019 (2)
- October 2018 (1)
- September 2018 (1)
- August 2018 (2)
- July 2018 (1)
- March 2018 (1)
- February 2018 (2)
- December 2017 (1)
- September 2017 (1)
- May 2017 (1)
- January 2017 (1)
- December 2016 (1)
- November 2016 (1)
- September 2016 (1)
- August 2016 (2)
- June 2016 (2)
- May 2016 (1)
- April 2016 (1)
- December 2015 (1)
- October 2015 (1)
- September 2015 (1)
- August 2015 (1)
- June 2015 (1)
- January 2015 (1)
- September 2014 (2)
- August 2014 (1)
- July 2014 (4)
- June 2014 (9)
- May 2014 (2)
- April 2014 (1)
- March 2014 (1)
- February 2014 (1)
- December 2013 (1)
- November 2013 (5)
- October 2013 (5)
- September 2013 (5)
- August 2013 (5)
- July 2013 (5)
- June 2013 (2)
- May 2013 (2)
- April 2013 (4)
- March 2013 (5)
- February 2013 (2)
- January 2013 (3)