Ten things to consider before replacing an existing dwelling
By Jake Edgley
1st November 2026
Ten things to consider before replacing an existing dwelling
It's an incredibly exciting prospect to build your own new build home from scratch - I know as I've done it myself more than once! However, it's good to have a clear idea of some of the drawbacks and alternatives before embarking on an ambitious newbuild, or even before considering a particular site.
There are many obvious advantages to a newbuild over a refurbishment project. You will not be restricted in design choices by the existing building so will be free to conceive of a house that is exactly as you would want it. You will have built the house from scratch so will know that the building is built to a high standard, from components and materials that won't need replacing for a time to come so maintenance costs will hopefully be minimal. You'll also be able to incorporate modern technology easily, for example with heatpumps and MVHR which can be difficult with an older structure.
However there are many ways in which a refurbishment project can be a financial and environmental improvement over a newbuild and it's good to understand these first. Broadly speaking, and without stating the obvious, the higher the quality of the existing building the less advantage there is in demolishing it before you start!
01
Value
The question of which approach is the most cost effective depends on how much of the existing building you are able to retain.
I think it's important to think of a refurb as being either a refresh or a total refurbishment. By this I mean one strategy is to leave as much of a building untouched as possible and add or repair where needed, and the other is to strip a building back to a structure for a full refurbishment. Financially the worst is to end up half way as you won't get the benefits of a full refurb but it could well cost the same.
If you are able to follow the first strategy and find a way to reconfigure and update a building while retaining as much as possible then this will likely be more cost effective than a newbuild. At Wrap House for example we left the interiors largely untouched and wrapped the whole building in insulation and new stainless steel cladding.
If however you are embarking on a full refurbishment, for example a back to brick rebuild, it will likely cost the same or more than a newbuild due to the added complexity of working around and repairing an existing structure.
It's also important to consider the end value as well- it's likely that a well designed and executed new home will be more valuable than a refurbished existing building which might tip the balance in favour of a newbuild. You'll need to research your local market but often in London a newbuild commands a 20% premium over equivalent older buildings
02
Reclaiming VAT
Often a big driver for replacing an existing dwelling is making use of the zero rate vat status of a newbuild, which effectively makes a newbuild 20% cheaper than a refurb contract of the same size.
However it's important to understand the implications of going for a full newbuild. Most obviously you will need to completely demolish the existing building, which will prevent you from making use of any part of the existing fabric of the building. There is also building control and planning to take into account, and the implications of this for a newbuild can be costly.
If you can make good use of the existing structure then this might well save more than the cost savings of zero vat, with the added advantage of less planning and building regulations burden.
03
Planning
The first question for many people will of course be can you get planning for a replacement dwelling.
It's likely you'll need expert advice to help on this point. However as a starting point I always think that the 'reasonableness' test is a good place to start. Does the site feel suitable for the house you want to build in terms of size and location? Will your proposed house sit well in its surroundings? If you want to build something contemporary then this is easier if either the site is well hidden or it is surrounded by similar buildings. Is it a sensible location in terms of pedestrian and vehicle access, and ideally access to public transport? Would it involve disturbing landscape that is particularly sensitive or protected? If the answer to any of the questions is no it does not mean a new house is impossible but it might be a good deal harder.
On the positive side, you are far more likely to be able to get planning on a site that has an existing building, particularly if it is already residential. An existing building establishes the principle of a building on the site, and in many areas for example a greenbelt location it's virtually impossible to get planning for a new house on a virgin site that does not have a building.
04
Can the existing building be demolished
If you want to replace a building, it goes without saying that you'll need to start with something that has no heritage value, as you might well be refused permission to demolish. In addition certain types of important buildings might be refused permission, such as a pub or theatre.
It's important to note that you often need planning consent to demolish a building- for example if the existing building is listed or in a conservation area then it cannot be demolished without planning consent. There are additional restrictions on many types of existing structures.
As a general guide, it's usually a good idea to retain a building until you have planning to replace it to avoid any issues
05
Are you changing the use of the site?
An application that requires a change of use is considerably more complex than a replacement dwelling, so if you are hoping to replace a non-residential building it's important to get some planning advice at an early stage. In certain parts of London for example you might be asked to put a commercial building on the rental market for two years to prove that the building is unwanted before you can even apply.
06
Size
It's important to be sure that you can get planning for a house that is large enough for your requirements. While an existing house will establish the principle of a residential building, there may be limitations on how much larger a replacement building can be. In many greenbelt areas, or in national parks, there is often a limit of 20-30% larger than the existing building was at a certain date in the past. Sometimes it's possible to include outbuildings to aid this calculation, but beware of a building that has already been extended, even if quite some time ago- if the cutoff date is before the existing extension you can find that your extension rights have already been used up.
You'll also be expected to not overdevelop the plot- as a rule of thumb this might be 50% of the total plot size.
07
Permitted development
It's also worth considering the permitted development rights of an existing building. We have had a recent project where a client wanted to replace an existing dwelling, but the planners pushed back on certain aspects of the project as part of a newbuild application. By reverting to a refurbishment approach we were able to deliver the same concept by making use of permitted development rights which can be quite extensive, and which cannot be refused by the planners.
08
Sustainability
If you can retain the existing structure of the building, perhaps by 'upcycling' it, there is a big environmental benefit to this. The environmental cost of building far outweighs the operational impact of the building, so it's undoubtably a good environmental strategy to make use of an existing structure.
Having said that, longevity is an important environmental consideration, and if your new building is built to a high standard that gives it a long life then this will in the long term be more sustainable than rebuilding a structure that has a limited lifespan.
In addition a new build will make it easier to accommodate environmental technologies such as MVHR and heatpumps, and to build a highly insulated structure that performs well
09
Building control
This is often overlooked in considering a newbuild over a refurbishment. It's important to note that the building control requirements for a newbuild home are rightly very demanding. If you have an open site in the countryside this might not be an issue- you'll want to build a well insulated home and most of the building regulations that apply to you will ensure that your home is functional and fit for purpose.
There are cases however where the newbuild regulations can be problematic, particularly in urban areas. For example a newbuild home must have a level access to the main living areas for disabled access, and if you have a steeply sloping plot this can be difficult to achieve. If you are retaining an existing building, for example with steps up to the front door, then you'll be able to retain these as long as you don't make the situation worse.
10
Time
There is an efficiency to the build of a new home- there is no existing structure to work around and restore, and there is a high degree of predictability. However this is offset by a longer lead in to the build. Planning can often be more demanding and time consuming than it is for altering an existing building, and there will be a complex detail design process that needs to be completed before you can start. Within certain parameters if you are refurbishing a building you can start as soon as you are ready, particularly if you are utilising PD rights.
Summary
Building your own new home can be an exciting, rewarding and financially worthwhile endeavour, but it's important to consider the implications from the outset, and to be sure that it's the best strategy for your particular site before you begin. Once the existing building has gone there is no going back!
By Jake Edgley
1st November 2026